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Alhuzaim- Metallurgy Page 1
WELDING Handbook
By:
Abdullah Alhuzaim
First addition
21-Jan-10
Alhuzaim- Metallurgy Page 2
Chapter 1: ARC WELDING POWER SOURCES
Power sources can be classified in to two category constant current and constant voltages
POWER SOURCES
CONSTANT CURRENT
(CC)
CONSTANT VOLTAGES
(CV)
CONSTANT CURRENT POWER SOURCE:
Means the power sources produce a relatively
constant load current. At a given loud current, the
load voltage is responsive to the rate of feeding the
consumable metal electrode. That’s mean if the arc
length varies results in slight changes in the arc
voltage, the welding current remain constant.
Constant Current power sources are generally used
for manual welding processes such as shielded metal
arc welding (SMAW), gas tungsten arc welding
(GTAW), plasma arc welding (PAW), or plasma arc
cutting (PAC), where variations in arc length are
unavoidable because of human element.
CONSTANT VOLTAGES POWER SOURCE:
Means the power sources produce a relatively
constant load voltage. The load current, at a given load
voltage, is responsive to the rate at which a
consumable electrode is fed into the arc.
Constant Voltage arc welding is generally used with
welding processes that include a continuously fed
consumable electrode, usually in the form of wire.
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Welding Process
R G 45 Rod Gas 45.000 min Tensile strength
OxyFuel Gas Welding:
The oxyfuel welding is one of the oldest welding
processes. The oxyfuel gas welding processes involve
melting the base metal and applying a filler metal if not
autogeneses weld (Filler Metal May or may not be
used) . The metal normally welded with the oxyfuel gas
welding process include carbon steel, low-alloy steel,
and most nonferrous metals, but generally not
refractory or reactive metals. The process is used to
weld thin sheet, tubes, and small diameter pipe, and
most commonly used for maintenance and repair.
Oxyfuel Gas Welding Variation
– Air Acetylene welding (AAW)
– Oxyacetylene welding (OAW)
– Oxyhydrogen Welding (OHW)
Filler Metal
The properties of the weld metal must closely match
those of the base metal.
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Three Types of Flame Adjustment
Carburizing Flame
Reducing (carburizing) flame- will add carbon used to weld non-ferrous material around 5300° F at 2x
flame.
Fig 2.1 Carburizing Flame
The acetylene feather is twice as long as the inner cone. It is used for soldering.
Fig. 2.2 Temperature of the oxyacetylene flame
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Neutral Flame
Neutral flame- around 5850° F has a 1 to 1 ration of acetylene and oxygen
Fig 2.3 Neutral Flame
Used for welding, cutting, and brazing
Oxidizing Flame
Oxidizing flame- has excessive oxygen temperature around 6300° F
Fig. 2.4 Oxidizing Flame
Used for braze welding
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Equipments required
Fig. 2.5 Oxyacetylene Equipment
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Fuel Gas Cylinder-
Porous filler soaked in acetone to stabilize acetylene
Left hand threads
Normal 250 P.S.I. pressure
Shorter container
Oxygen Cylinder-
Taller container
Normal 2400 P.S.I. pressure
Right-hand threads
When not in use they should be stored with cap on, and they should be chained
Fuel Gas Regulator-
It takes high pressure of cylinder and reduce to usable pressure
Can be single or dual stage
Dual will maintain the same pressure as cylinder pressure changes
Oxygen regulator-
right hand threads designed for higher pressure
Hose/check valves-
normally green and red in color
left-and right-hand threads
check valves prevent burn back located at the handle and at the regulator
Torch-
directs flame
mixes oxygen and acetylene
torches are designed for specific applications
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Fig 2.6 torch & regulator
Tips Based on Application
(cont.)
WELDING GOUGING
HEATING
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Fuel Gases
Acetylene
6000° F
good for welding and cutting hottest
Fig 2.7 Acetylene Flame
Methylacetylene Propadiene (Mapp Gas)
5300° F
not used for welding
good for cutting
inner cone 1-11/2 times acetylene
Fig. 2.8 Mapp Flame
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Propane
4600° F
Not used for welding
Used for cutting or brazing
Slower travel speed
Fig. 2.9 Propane Flame
Natural
4780° F
not used for welding
used for cutting or brazing
Fig. 2.10 Natural Flame
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Materials Weldable
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Shielded Metal Arc Welding (SMAW)
Fundamentals of the Process
Definition
•Shielded Metal Arc Welding- is an arc welding process wherein coalescence is produced by heating with an electric arc between a covered metal electrode and the work.
•Shielding is obtained from decomposition of the electrode covering.
•Pressure is not used and filler metal is obtained from the electrode.
Process Principles
•Heat Source- Heat of the arc
•Shielding Gas- Slag formed by the decomposition of the flux
•Filler Metal- Comes from the core wire
•Flux contains-
–deoxiders (slag formed ionizing elements) to stabilize the arc
–iron powder for higher deposition
–alloying elements
2.4 Methods of Application
•Manual- most widely used
– approximately 99%
•Semiautomatic- not used
•Mechanized
•Automatic- gravity/massive/firecracker
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2.5 Metals Weldable
Position Capabilities
•Grooves- all positions
•Fillets- all position
•Limitations-
– size of electrode
– skill of operator
– type of electrode
Electrical Requirements
Welding Circuit
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Welding Current Types
AC
DCEN (Straight) Polarity
DCEP (Reverse) Polarity
Power Source Type and Characteristics
1) Generator (DC) 2) Transformer (AC) 3) Rectifier (DC) 4) T.R. (AC/DC) 5) Alternators (AC) 6) Inverters 7) Constant Current 8) 60% Duty Cycle
Advantages
1) Low cost of equipment 2) Maximum flexibility 3) Thickness range unlimited
Disadvantages
1) Low operator factor (rate) 2) Low filler metal utilization 3) Slag removal 4) Primarily for ferrous metals
Mild Steel (Covered) Electrode Classification
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1) Flat, Horizontal, Vertical, Overhead 2) Flat and Horizontal only 4) Flat, Horizontal, Vertical Down, Overhead
*for electrodes 3/16” and under, except 5/32” and under for classifications E7014, E7015,
E7016, and E7018
Stainless Steel Electrode Classification
Electrode Groups
•F-1 High Deposition Group
–(Exx20, Exx24, Exx27, Exx28)
•F-2 Mild Penetration Group
–(Exx12, Exx13, Exx14)
•F-3 Deep Penetration Group
–(Exx10, Exx11)
•F-4 Low Hydrogen Group
–(Exx15, Exx16, Exx18)
Type of Coating
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Gas Tungsten Arc Welding (GTAW)
Fundamentals of the Process
Definition
Gas Tungsten Arc Welding (GTAW)- An arc welding process that uses an arc between a tungsten electrode (non-consumable) and the weld pool
the process is used with shielding gas
and without the application of pressure
Slang Names
T.I.G.-Tungsten Inert Gas
Heliarc
W.I.G.-Wolfram Inert Gas
Wolfram is German for Tungsten
Process Principles
Heat source- heat of the arc between a non-consumable electrode and the work
Shielding- inert shielding gas
Filler metal- will match base metal composition
Flux- not applicable
Metals Weldable The process was originally developed for the hard to weld metals and can be used to weld more, different kinds of, metals than any other arc welding process. Such as…
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Position Capabilities
Grooves- all position capabilities
Fillets- all position capabilities
Limitations- skill of the operator
Base Metal WeldabilityAluminum Weldable
Bronzes Weldable
Copper Weldable
Copper Nickel Weldable
Cast, Malleable, Nodular Possible but Not Popular
Wrought Iron Possible but Not Popular
Lead Possible but Not Popular
Magnesium Weldable
Inconel Weldable
Nickel Weldable
Monel Weldable
Precious Metals Weldable
Low Carbon Steel Weldable
Low Alloy Steel Weldable
High and Medium Carbon Weldable
Alloy Steels Weldable
Stainless Steels Weldable
Tool Steels Weldable
Titanium Weldable
Tungsten Possible but Not Popular
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Electrical Requirements
Welding Current Type DCEN DCEP AC Power Source Type and Characteristics
Transformer- AC- constant current
Rectifier- DC- constant current
Other Electrical Requirements
Program ability
Hot start
Slope control
Consumables
Filler metal selection
Gas selection
Tungsten electrode selection
Gas Selection
Argon- is the most common
heavy which allows for lower flow rates
provides the best arc starting.
Helium- provides a hotter arc
higher travel speeds
lighter, therefore, higher flow rates must be used
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Electrode for GTAW
Low Alloy (Solid) Electrode Classification GMAW, GTAW, and PAW
Stainless Steel (Solid) Electrode Classification GTAW Process
ER - 308 L S Electrode or Rod Chemical Low Carbon Content High Composition .04 Maximum Silicon
ER 80 S - Ni 3 Electrode or Rod Tensile Strength Solid or Chemical Composition KSI Metal Cored
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Aluminum (Solid) Electrode Classification GTAW Process
Types of Tungsten Electrodes (GTAW & PAW)
ER 4043 Electrode or rod Chemical Composition
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Advantages
Will make high quality welds in almost all metals
Very little, if any, post-weld cleaning required
Disadvantages
Lower productivity
Higher initial cost of the equipment
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Gas Metal Arc Welding (GMAW)
Fundamentals of the Process
Definition Gas Metal Arc Welding (GMAW)- An arc welding process that uses an arc between a continuous filler metal electrode and the weld pool the process is used with shielding from an externally supplied gas without the application of pressure
Process Principles
Heat source- electric arc between electrode (wire) and the work
Shielding- an external gas supply
Filler metal- fed automatically from a spool or reel
Flux- not applicable Transfer Mode with GMAW
Short Circuit
CO2 or AR/CO2
low amperage and voltage
all positions Globular
CO2 or AR/CO2
higher amperage and voltage
flat and horizontal
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Spray- AR/O2
High amperage and voltage
flat and horizontal
Pulsed- AR/O2
various amperage levels
spray transfer
all positions
transition current
Metals Weldable
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Position Capabilities
Grooves– all position capabilities
Fillets– all position capabilities
Limitations- type of transfer o Skill of operator o Wire size
Electrical Requirements
Welding Circuit
Welding Current Type
DCEP- normal type of current used
DCEN- can be used with special electrodes
AC- has not been successfully used Power Source Types and Characteristics Constant Voltage- 100% duty cycle with flat volt/amp curve Shielding Gas
Inert- a gas that does not combine chemically with the base or filler material
Carbon Dioxide- not inert, is the most common gas used on low carbon steel
75% Argon,25%CO2- is used to produce a smoother bead with less spatter, but will reduce penetration
Argon/Oxygen- this mixture with 5% Oxygen as maximum will produce a spray transfer with no spatter
Advantages
High deposition rates related to S.M.A.W.
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High utilization of filler metal
Elimination of slag
Reduction of smoke and fumes
Easily automated
Extremely versatile Disadvantages
Higher equipment price
Not as flexible as SMAW
Winds and drafts affect shielding gas
Some problems with feeding small or soft wire Classification
Mild Steel Classification
ER 70 S - X
ELECTRODE OR ROD
MINIMUM TENSILE STRENGTH IN KSI
S = SOLID ELECTRODE WIRE
CHEMICAL COMPOSITION AND SHIELDING
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5.14 Stainless Steel (Solid) Electrode Classification
GMAW Process
Aluminum (Solid) Electrode Classification
GMAW Process
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Flux-Cored Arc Welding (FCAW)
Fundamentals of the Process
Definition Flux-Cored Arc Welding(FCAW)- An arc welding process that uses an arc between a continuous filler metal electrode and the weld pool. the process is uses with shielding gas from a flux contained within the tubular electrode with or without additional shielding from an externally supplied gas and without the application of pressure
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Process Principles
Heat Source- an arc between a continuous filler metal electrode and the weld pool
Shielding- is obtained from flux contained within the tubular electrode and without additional shielding from an external supplied gas
Filler Metal- is obtained from a continuously-feeding tubular electrode
Flux- will provide deoxidizers, ionizers, purifying agents, and in some cases alloying elements
6.4 Methods of Application
Manual N/A
Semiautomatic Most Popular
Mechanized widely used
Automatic widely used
6.5 Metals Weldable
Base Metal Weldability
Cast Iron Using Special Electrode
Low Carbon Steel Weldable
Low Alloy Steel Weldable
High and Medium Carbon Weldable
Alloys Steel Weldable
Stainless Steel -- Selected Limited Types
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Position Capabilities
Grooves- all positions, depending on size and type
Fillets- all positions, depending on size and type
Limitations- would depend on the skill of the operator
Electrical Requirements
Welding Circuit
Welding Current Types
DCEN or DCEP
depending on type of wire
Power Source Type and Characteristics
Constant voltage with flat volt amp curve
Constant speed system with a constant current machine
The wire feeder is a variable speed system
100% duty cycle
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SHIELDING MEDIUM AND POWER
XE 7 0 T
ELECTRODE
MINIMUM TENSILE 10XKSI
WELDING POSITION (0-F&H, 1-All)
TUBULAR OR FLUX CORED
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Advantages
High quality welds
High deposition rates
Less pre-cleaning required
Relatively high travel speeds
Easily mechanized
Disadvantages
Equipment is more expensive
External gas shield
May be affected by breezes and drafts
Slag needs to be removed
Primarily only welds steels
Very smoky process
Filler metal more expensive
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Submerged Arc Welding (SAW)
Fundamentals of the Process
Definition Submerged arc welding (SAW)- an arc welding process that uses an arc or arcs between a bare metal electrode or electrodes. The arc and molten metal are shielded by a blanket of granular flux on the workpiece The process is used without pressure and with filler metal from the electrode and sometimes from a supplemental source (welding rod, flux, or metal granules)
Slang Names
Quick fill
Sub arc
Welding under powder
Process Principles
Heat source- an arc between a bare metal electrode and the work
Shielding- arc and molten metal are submerged in a blanket of granular fusible flux and the work
Filler metal-bare solid wire or composite
Flux metal-cored electrode- granular mineral compounds mixed according to various formulations.
The three different types of fluxes are fused, bonded and mechanically mixed Metals Weldable
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Position Capabilities
Grooves- horizontal groove with backing and flux troft.
Fillets- horizontal fillet position
Limitations- because of large pool of molten metal process is known as limited position welding
Electrical Requirements
Welding Circuit
Welding Current Types
AC
DCEN
DCEP Power Source Type and Characteristics
Alternating current
DC constant- voltage
DC constant- current
CC/CV combination
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Other Electrical Requirements
Controls- motion timers, pulse, crater fill
Weld heads- wire feed motor and feed roll assembly
Torches- guides the wire through the contact tip and delivers welding power to the wire at the contact tip
Additional Equipment
Travel equipment
Flux recovery units
Fixturing equipment
Positioning equipment Electrode Selection Mild Steel Classification
E- indicates a solid electrode
X- manganese content
X- carbon content
X- deoxidation
X- suffix
7.10 Mild Steel Flux and Electrode Classification
SAW Process
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Electrode Classification
Electrode Selection Flux Classification
F- indicates flux
X- minimum tensile strength
X- condition of heat treatment (A or P)
X- impact strength- lowest temperature
Submerged Arc Flux Classification System
Advantages
High quality weld metal
High deposition rates
Smooth, uniform finish, no spatter
Little or no smoke
No arc flash
High utilization of electrode wire
Easily automated
Manipulative skills not involved Disadvantages
Limited welding position
Primarily to weld steels
In semi-auto welding, hard to see the arc
E C X XX X X
Carbon Suffix which Electrode Manganese Content indicates alloy Content x0.01 present (in low-alloy steel)
L- low (0.60 Mn max.) M- medium (1.25 MN max.) Deoxidation H- high (2.25 Mn max.) Practice
Indicates composite K indicates electrode – omission silicon killed of C indicates solid electrode
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Material selection is based on
Material properties:
o Mechanical properties
Strength
Hardness
Ductitility
Toughness
Stiffness ……est.
o Physical properties
Density
Melt temp
Thermal conductivity
Thermal expansion…..est.
o Chemical properties
Corrosion resistance
o Other properties
Cost
Availability
Business Issues
Main types of failure in engineering material:
1. Mechanical overload (deformation or fracture)
2. Corrosion
3. Wear
Stress concentrators (stress risers):
Geometrical feature that causes the stress in that area to be higher than the applied stress.
Stress: force per unit area
or PSI or
or Pascal (P)
Strength: ability of material to resist an applied stress.
Examples of stress risers:
Sharp radius on corners
Weld under cut
Excessive weld reinforcement
Surface roughness
Smax=Sn X Kf
Smax = stress at the stress riser
Sn= applied stress
Kf= stress concentration factor
Kf= 1 when no stress riser is present
Smax=Sn
Kf > 1 when a stress concentrator is
present Smax>Sn
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Chemistry Review:
Element- a pure substance that cannot be broken down into a simpler substance
Atom- smallest part of an element that retains the properties of the element
Atoms are made of:
Protons: positive charge in nucleus
Neutrons- no charge in nucleus
Electrons- negative charge orbit nucleus
Atomic bounding:
Bonding occurs the atom wants to be at their lowest energy state.
*this is usually when they have full other electron shells.
Types of Bonding:
Ionic Bonding:
o One atom gives its valance electron(s) to another atom.
o Valance electrons will remain in fixed position.
o Most ceramics have Ionic Bonds
Covalent Bonding
o Adjacent atoms share valance electrons
o Electrons are in fixed positions (poor electrical conductivity)
o Most monomers have Covalent Bonding
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Van-Der walls
o Weak electrostatic bonds
o Important for plastic
Metallic Bonding
o Valance electrons move from one atom to the next making all atoms “feel” like they
have full valance shells.
Properties of metals:
Most are good electrical conductors
Most are solid at room temperature
Most have good thermal conductivity
Plastically deform with force
Expand when heated
Most are opaque “can’t see through”
Most are shinny
Most metal are not used in their pure form
Alloys- Combination of metallic elements with other metallic or non-metallic elements.
Composition- how much of each element is present in the alloy in weight %
Phase- area within an alloy that has the same:
o composition
o crystal structure
o properties
Crystalline- atoms are arranged in a 3-dimensional pattern in the solid state.
*Most metal are crystalline
Amorphous- atoms do not have a 3-D arrangement in the solid state
States of Matter:
Temperature and pressure will determine what state a substance is in:
1. Solid: fixed volume, fixed shape
2. Liquid: fixed volume, assumed shape of containers
3. Gas: volume and shape not fixed
Example:
Steel = Fe + C
Cast Iron = Fe + C + Si
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4. Plasma
Solidification of metals:
Solidification is a three stage process.
1. Nucleation: two atoms that are close to each other from a chemical bound
*accurse at many locations in the liquid
2. Growth: additional atoms bond to the nucleus and growth accurse in 3 dimensions.
3. Formation of grains boundaries: area where crystals of different orientation meet the area
between them called a grain boundary
Grain- Area with a metal where the atoms have the same orientation.
Most metal are crystalling: atom are arranged in three dimensional patterns (in the solid state)
in the other hand, some metals are Amorphous: atoms are not in a three dimensional pattern.
Main crystal structures for metals:
1. Face Centered Cubic (FCC)
a. Tend to be soft and ductile (Al, Cu, Pb)
2. Body Center Cubic (BCC)
a. Tend to be stronger and less ductile (Fe @ room temp.)
3. Hexagonal Close Packed (HCP)
a. Tend to be brittle (Zn, Mg)
4. Body Centered Tetragonal
a. Harder and stronger (Quench Hardened steel →Martensite)
Allotropic Phase Transformation:
Metal that change crystal structure with temperature
Example: Fe
Room temp - 1660 BCC
1661 – 2550 F FCC
2551 – 2800 F BCC
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Most metal only exist in 1 crystal stricture. However, some metal change crystal structure with
temperature. This is called on Allotropic transformation.
Crystal Defects will occur during solidification:
Two main types of defects occur
1. Vacancy
a. missing atoms at some location within a metals crystal structure
b. these control diffusion
2. Dislocation
a. missing ½ planes of atoms in a metal crystal structure
*These allow metal to plastically deform (bend, stretch, etc..)
Dislocation can only move in specific directions in each crystal structures. These direction are called slip
planes.
FCC- 4 slip planes, dislocation can move in various directions. These metals tend to be soft and ductile
(Cu, Pb)
BCC- 2 slip planes at 90° (perpendicular) to each other. These tend to be stronger and less ductile (Fe at
room temperature)
HCP- 2 slip planes parallel to each other. Tend to be brittle (Zn, Ti)
Grain size (number of grains/Unit area)
Will affect strength and ductility
small grain size stronger and less ductile
Larger grain size lower strength and more ductile
Grain size can be controlled by the rate of solidification
Slow solidification larger grain size
The crystal in nature of metals causes their mechanical properties to be Anisetropic (properties vary
with direction).
Stress: Force per unit area applied to a
material (Ibf/In² pound of force or N/M²)
Pascal
Strain: Movement of the material due
to an applied stress (In/In or m/m)
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There are two type of strain exist
1. Elastic Strain: movement that occurs when a stress is applied and disappears when the stress is
removed.” Occurs due stretching atomic bonds.”
2. Plastic Strain: permanent change in shape that accurse due to an applied stress.
*Anything that limits dislocation motion will increase the strength of metal alloy
Loads:
Type of load Stress produced Example
tension cable
compression Column
Compression/Tension Beam / Gear teeth
Shear stress Bolts
Shear Stress Drive shaft
Types of loading
Static loading: constant load – no change
Dynamic loading: change with time
Impact loading: load applied at a rapid rate
atigue loading: cyclic loading (load, unload, load, unload…)
Four methods to increase strength of metals
1- Work hardening (cold working, strain hardening)
a) Done by plastically deforming the metal at temperatures below the alloys
recrystalization temperature (
melting temperature ( )
b) Causes dislocations to move to barriers such as grain boundaries & additional stress is
required to move other dislocations & cause additional plastic deformation.
c) Effects of work hardening can be removed by annealing or normalizing
i. Heat above recrystallization temperature & air cool
ii. Produces lower strength, lower hardening, & higher ductility “compare to work
hardening alloy”
*All metal alloys can be work hardened.
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2- Solid solution strengthening
a) Adding alloying elements that block dislocation motion & increase the strength of the
alloy
b) All alloys can be strengthened within this method.
c) Effect cannot be removed by heating & cooling from welding
3- Quench Hardening (Quench & Tempered, Transformation Harding)
a) Heat treatment used to increase the strength of ferrous alloys such as:
i. Steel
ii. Stainless steel
iii. Cast iron
b) Alloy must have > 0.30% carbon to quench harden
c) Process steps to Quench harden
i. Heat alloy to its austenitization temperature (upper transformation temp
ii. Hold at temp for microstructure to transform to austenite
iii. Quench- rapidly cool faster than critical cooling rate & case microstructure to
transform to martensite
Martensite- Body centered tetragonal (BCT) steel microstructure that is more difficult
for dislocations to move in (it has less slip planes)
Martensite is strong hard and brittle→ In most welding applications you want to avoid
the formation of martensite in the HAZ due to its tendency to crack
4- Precipitation Hardening
a) Heat treatment used to increase the strength of:
i. Some aluminum alloys (2XXX, 6XXX, 7XXX)
ii. Some stainless steels (17-4PH, 17-7PH)
iii. Some Titanium alloys
iv. Some Ni & Co alloys
b) Process step to precipitation hardening
i. Solutionice- heat alloy to form a single phase solid solution
ii. Quench- cause single phase solid solution to remain at room temp
1. This does not cause on increase in strength
iii. Age-reheat the alloy (to a lower temp than used for solutionicing) & hold at
temperature
1. This cause small intermetallic precipitates (hard particles) to form within
the grains of the alloy
2. These increase strength (when precipitates are small)
*The heat of welding will cause overaging to occur in the HAZ →this results in a loss of strength
in HAZ
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Tensile Testing:
Most common test used to determine the strength of a material.
Test is preformed in a sample of known geometry
o Round Bar
o Flat Coupon
Sample is clumped between the machine cross heads and the cross heads move away
from each other at a set speed
The load (Ibf) and change in length are measured during the test
Prior to starting the test a gage length is worked on the sample (2.000 inch typ)
We calculate the stress as:
We calculate the strain as:
Data is plotted as an Engineering Stress Strain curve
Stress =
Strain
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The initial part of the curve is linear (stress and strain)
o This is the “Elastic Region” of the curve (due to stretching of atomic bonds)
o Elastic region- only elastic strain is occurring
o Dislocations are NOT moving, atomic bonds are stretching
Elastic Limit:
Max stress a material can withstand before it begins to plastically deform.
0.2% Yield Strength:
Found by drawing a line parallel to the elastic region of the curve offset 0.2% on the strain Axis
This valve is most often used for design calculations
0.2% is most often used for design calculation
Ultimate Tensile Strength
Max stress the metal can withstand prior to failure
Break Strength
Stress at point of fracture
*% Elongation & % Reduction are measures of the alloy Ductility
Modulus of Elasticity- Elastic Stiffness
-Determines how much the metal will deflect under elastic loading conditions
Ultimate Tensile Strength
Break Strength
s
% Elongation=
s
% Reduction in Area=
s
Alhuzaim- Metallurgy Page 47
Modulus of all steel at Room temperature ≈30 X 10⁶
Modulus of all aluminum at room temperature ≈ 10.5 X 10⁶
o Modulus of Elasticity (E) is dependant of the strength & ductility of the alloy
- Modulus is controlled by the stretching of atomic bonds
* Temperature could change the modulus of elasticity
o Resilience- ability of metal to absorb energy without plastic deformation
- Estimated by the area under the elastic region of the stress strain carve.
o Toughness- ability of a metal to absorb energy before fracture
- Estimated by the total area under the stress-strain curve
o Toughness can be also be measured with an Izod or chirpy impact test
- These test determine impact toughness which is depending on the size of the sample &
speed of impact loading.
Modulus of Elasticity →E =
(measure in elastic portion of the curve
Resilien
ce
Alhuzaim- Metallurgy Page 48
- measure how much energy is absorbed by the sample
- Results are typically plotted Vs. test temperature
Plane strain fracture toughness:
- This is a material property that is independent of thickness and strain rate
- Determined by applying a tensile stress to a sample that has a crack of known size and location
if any 2 of the 3 variables (KIC, δ, ) are known we can solve for the third
the ability of a material to resist the growth of a flow (i.e. have a large KIC) depends on many
factors:
1. Large flaws reduce the allowable stress. Therefore manufacturing process that reduce
the flow size improve fracture toughness often times parts can be inspected (X-ray,
ultrasonic est.) to assure flaws above a critical size are not present in a part
2. Ductility of the material is critical. If the material can plastically deform at the tip of
the crack it will reduce the stress intensity factor.
a. Higher strength
3. Increasing temperature will typically increase the KIC
4. Small grain size typically increases the KIC
K1C= plane strain fracture toughness
K1C=fδ√
F=constant 1.12 (edge crack)
δ=applied stress
=crack diameter
Alhuzaim- Metallurgy Page 49
Example 1:
Grade 350 maraging steel
=0.10 in → =0.05 in
KIC= 35 KSI solve for δ
Answer:
35 KSI√ = 1.12 X δ X √ →
This is the stress required to make a crack of (0.10 in) in radius grow to failure
**************************************
Yield Strength is 325 KSI design is limited by the plane strain fracture toughness (KIC) not by the Yield
Strength
Example 2:
Look at grade 350 maraging steel that is quenched and tempered to produce the following:
Y.S. = 225 KSI
KIC = 50 KSI √
What is the maximum safe stress if the max crack radius ( ) is 0.10 in?
Answer:
K1C=fδ√ → 50 KSI√ = 1.12 δ √ = δ = 113 KSI
*************************************
K1C=fδ√
δ = 78.8 KSI
Alhuzaim- Metallurgy Page 50
Hardness:
Mechanical property of metals
Harness can be measured many ways
o Resistance to indentation (Rockwell, Brinell, Vickers, Knoop)
o Elastic Rebound (shore – not typically used)
o Resistance to abrasion (file)
Hardness relates to wear resistance but is not a direct measure
Hardness also relates to the strength and ductility of metal
Higher hardness → higher strength
Higher hardness → lower ductility
* Maximum hardness of quench hardened steel is
Homework #1
1. A spherical pressure vessel is to be constructed by welding curved steel plates. The welds are
inspected by radiography using a technique that will detect any crack greater than 0.10 in. long. Three
grades of maraging steel are being considered;
I. 18Ni(grade 200)
II. 18Ni(grade 250)
III. 18Ni(grade 300)
If the thickness of the vessel is 1.00 in. and the diameter is 10 ft., which steel will give the greatest
pressure capability? Use the ASM Metals Handbook for material properties.
I. 18Ni(grade 200)
K1C=fδ√ → 140 KSI √ = 1.12 δ √ = 315 KSI
K1C=fδ√ → 220 KSI √ = 1.12 δ √ = 495 KSI
Rule of “thumb” for steels
500 X BHN U.T.S (PSI)
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δ for 18Ni(grade 200) between 315-495
II. 18Ni(grade 250)
K1C=fδ√ → 110 KSI √ = 1.12 δ √ = 247 KSI
III. 18Ni(grade 300)
IV. K1C=fδ√ → 73 KSI √ = 1.12 δ √ = 164 KSI
Spherical vessel surface area:
10 ft→ 120 in – 2 in = 118 in /2 →radius of 59 in
Area = 4 π r² → 43743.5 in²
Stress =
force = stress X area = Ib
I. 18Ni(grade 200)
315 X 43743.5 = 13779202.5 Ib
495 X 43743.5 = 6820705238 Ib
II. 18Ni(grade 250)
247 X 43743.5 = 10804644.5 Ib
III. 18Ni(grade 300)
164 X 43743.5= 7173934
So we conclude that the steel that will give us the greatest pressure capability is 18Ni(grade 200)
2. Describe what maraging steels are.
Maraging steels: comprise a special class of high-strength steels that differ from conventional steels in
that they are hardened by a metallurgical reaction that does not involve carbon. Instead, these steels
are strengthened by the precipitation of intermetallic compounds at temperatures of about 480 °C
(900 °F)
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FATIGUE:
- Fatigue is due to cyclic loading (load.. unload.. load.. unload)
- Fatigue failure can occur in metals at stress below the alloys Elastic limit
- Fatigue test results are typically shown in the form of S-N curves
o Endurance Limit
- below this stress the fatigue life is infinite
- Only steel and titanium alloys have endurance limits
o Fatigue strength
- Stress required to produce failure after 5x10⁸ stress cycles
- Al alloys and other non-ferrous alloys do not have Endurance limits so fatigue strength
are used for design calculations
- Fatigue fracture surfaces will have “Clan shell” or “Beach marks”
Fatigue failure zone
Steels & Titanium alloy
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Steel Microstructures:
Phase – area within a metal that has same composition properties, and crystal structure
3 way elements combine in the solid state
1. Solid solution- elements are soluble in each other and combine as a single phase
2. Mechanical Mixture- elements remain as separate phases (example: Oil & water)
3. Compound- elements react together to form a phase with properties different that the
elements that are reacting (example: 3Fe + C → e₃C)
Steel Microstructures
Name of phase Type of phase Amount of carbon Properties
Ferrite (α Iron)
Single phase solid solution of carbon in BCC Iron
0.025% max @1333 ˚
Soft and ductile (40 – 50 KSI) T.S Elongation
Iron carbide ( e₃C, Cementite)
Compound 6.67 wt % carbon (fixed ratio)
Hard and Brittle 325 KSI T.S 0% Elongation
Pearlite Mechanical mixture of errite and e₃C (2 phase solid)
0.8% @ the Eutectoid Composition
Fall between Ferrite & e₃C ( 125 KSI tensile strength, 15% Elongation)
Austenite (δ Iron)
Single phase solid solution of carbon in FCC iron
Max of ≈ 2.0% @ 2075 ˚
* Not tested, only exists at elevated Temperature
* Ferrite, Cementitem, Pearlite, and Austenite are all equilibrium steel microstructure
Equilibrium microstructure are produced by slow cooling
Alhuzaim- Metallurgy Page 54
Non-Equilibrium Steel Microstructures:
Name of phase Type of phase Amount of carbon Properties
Martensite Supersaturated solid solution of carbon in body centered tetragonal (BCT) iron
Up to 2.0% Hard, strong & brittle Maximum hardness carbon & above
Martensite is produced by cooling a steel from the austenite phase faster than the “critical cooling rate” for that alloy
Bainite Mechanical mixture of ferrite & e₃C
0.8% @ the Eutectoid Composition
Harder, stronger & less ductile than pearlite, but not as hard as martensite
Bainite is produced by cooling a steel too fast to form pearlite but not fast enough to form martensite bainite is a “finer grain size pearlite
Alhuzaim- Metallurgy Page 55
Chapter 2:
Welding Metallurgy
Weldability- the “ease” with which as alloy can be welded
o To determine the weldability for a specific situation we must know:
- Base metal composition → (this is the primary consideration)
- Service conditions
i. Service temperature
ii. Types of loading (static, impact)
iii. Environment (corrosion requirements)
- Design of weld joint
i. Thickness
ii. Restraint
- 2 things must important to determine weldability of steel
1. Hardenability – how likely is it that martensite will be formed in the HAZ of the
weld
This is determined by the carbon equivalent (CE)
* If the CE> 0.4% than martensite is likely to form in HAZ & Procedures must be used to prevent this
otherwise cracking of the HAZ is likely.
- The following procedures are usually required for steels with CE>0.4%
a) Preheat & interpass temperature control
i) Reduce cooling rate of the HAZ & prevent formation of martensite
ii) Reduce residual stress by reducing shrinkage
b) Use low Hydrogen process or fillers
i) Hydrogen in the weld contributes to cracking (Hydrogen Cracking)
c) Minimize joint restraint
i) Reduces residual stress & reduces tendency for cracking
d) Post weld heat treatment (PWHT)
i) Reduces hardness & strength in HAZ → improve ductility & toughness
CE=%C +
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ii) Reduce residual stress
Types of Cracking:
Macrocrack- crack that is visible to the naked eye (may or may NOT extend to the surface)
Microcracking- only visible with the aid of a microscope (may or may NOT extend to the surface)
Intergranular- cracking a long the grain boundaries
Intragranular- cracking through the grain boundaries
o Cracks that occur after the weld has solidified are called (Hydrogen cracking, Cold
cracking, Delay cracking, underbead cracking)
Occurs in HAZ may extend into the weld metal or base metal
o Hydrogen cracking
- Type of cracking that occurs in the steels with high hardenability (high CE)
- 4 requirements for hydrogen cracking to Occur:
i. Diffusible hydrogen present in the area of the weld (H not H2)
ii. Temperature below 300 °F
iii. Susceptible microstructure
- Partially or wholly martensitic (>30 HRC ot it will not crack)
- Hardness is controlled by the amount of carbon (more
carbon ↑ HRC)
iv. Tensile stresses in the area of the weld (residual or applied)
o Hydrogen cracking can be avoided by preventing any 1 of these 4 requirements.
o Methods to prevent diffusible hydrogen from being present
Source of Hydrogen
- water (on base metal, in flux , in shielding gas, at atmosphere or on filler)
- rust (on the base metal, on filler)
- oil (on base metal)
- paint, marker, etc (on base metal)
o Need to use low Hydrogen processes or low Hydrogen Electrodes
o Methods to prevent martensitic microstructure in HAZ
i. Use preheat & interpass Temperature control
ii. Reduces cooling rate & prevents formation of martensite
This also allows additional time at elevated temperature for Hydrogen to
diffuse out of the weld area.
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Solidification Cracking
Cracking that occur during solidification of the weld due to tensile stresses from contraction
during cooling
Solidification cracking occur in the weld metal and may extend into the HAZ and base metal
Liquation crack occur at the interface between the weld and HAZ
Two conditions are required for solidification cracking
1. Metal must lack ductility at its solidification temp
This is alloys dependant
Aluminum alloys, fully austenitic stainless steel, and Mg alloys are most prone
On cooling grains are nucleated and grow until they join together and form a
coherent but not completely solidified mass
At this point some alloys are brittle
2. Tensile stress due to weld contraction must exceed the UTS of the weld metal at its
solidification temp
Weld bead geometry related and base metal residual stress related
Weld bead geometry avoid welds that are concave
This produces tensile stresses on the weld
Weld bead geometry avoid base metals with high amounts of residual stress
The higher the degree of restraint the more likely a given alloy will experience
solidification cracking
Max restraint occurs with 2 thick plates clamped and joined by a weld of small cross section
Most weld metals will crack
Min restraint occurs in large welds on thin close butting sheets
Shrinkage cracking
- A type of solidification crack
- Due to inadequate feeding of liquid metal to feed gaps caused by shrinkage during solidification
- Common in welds where penetration is too deep relative to weld width (laser, E beam)
- Width/Depth of 1-1.4 are best to avoid this problem
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Chapter 3
Stainless Steel:
Steel alloys with >11% Cr
Causes a chromium oxide layer to form on the surface of the steel that is tenacious and protects the
steel from additional corrosion.
Types of Stainless Steel
1. Ferritic
2. Austonitic
3. Martensitic
4. Duplex
5. Precipitation Hardened stainless steel
Ferritic Stainless steel
- 11.5 – 30% Cr
- Up to 0.2% C
Low carbon causes ferrite to be stable (will NOT transform to martensite)
- Used mainly for Auto Exhaust, Trim
- Ferritic Stainless Steel tend to be lowest Cost of all Stainless Steel
- Classifications are some of the 4XX series alloys 409, 439 both very common
Two main issues associated with welding Ferritic Stainless Steel
1. Grain growth in HAZ will result in loss of toughness
Lower heat input is better
2. Intergranular corrosion due to formation of chromium carbides (Cr23C6)
o In the HAZ where the Cr23C6 forms there will not be enough Cr available to form the
protective oxide layer and therefore corrosion will occur in this area
o Intergranular corrosion of erritic stainless steel is prevented by using “stabilized”
grades of stainless steel for applications that require welding.
o Stabilized grades have Ti or Cb/Nb added to them which causes the formation of TiC or
CbC in the HAZ and the Cr remains available to form the protective oxide layer.
Most Common
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Austenitic Stainless steel
- Up to 0.1% C
- 16-26% Cr
- 8-22% Ni (makes Austenite phase stable at and below room temperature)
- 2XX series (manganese used to replace same Ni for reduced cost)
- 3XX series (standard series)
- Work harden to high strengths
- High cost due to Ni & Cr
- Excellent corrosion resistance
o Food grade Stainless Steel
o Petro chemical applications
- Three main welding issues
1. High amount of distortion due to high thermal expansion (≈50% higher thermal
expansion than non-austenitic steels)
2. Intergranular corrosion (like in Ferritic Stainless Steel)
Prevented in Austenitic Stainless Steel by using
i. Low carbon grades 304L (0.03%C) not 304 (0.08%C)
ii. Use stabilized grades with Ti or Cb (316 Ti)
3. Solidification Cracking
Welds that are 100% Austenitic are very likely to crack
- Most Austenitic filler metals are formulated so the deposited filler metal contains Ferrite
- Ferrite acts as a “sink” for imparities that cause cracking
- Alloys that contain Ferrite have a smaller solidification temperature range
- Ferrite lower the coefficient of thermal expansion and therefore lower shrinkage stresses
- Two phase microstructure makes for a more “tortuous” crack path
- The ferrite content in the weld can be calculated using
o Schaeffler Diagram
o DeLong Diagram
o WRC 1992 Diagram
*Ferrite number usually from 5-15
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Martensitic Stainless steel
- Some of the 4XX series (403, 410, 420, 440)
- 11.5-18% Cr
- Up to 1.2% C
- Martensitic Microstructure
- Excellent hardness and Strength
- Good Corrosion Resistance
- High hardenability
Prone to hydrogen cracking (cold cracking)
- The higher the carbon in the steel the harder the Martensite
(HRC > 30 is very likely to crack)
- Weldability is similar to steels with high hardeability
400-600 ˚ preheat is typically used
- Post weld tempering is required to restore toughness in the HAZ
- Austenitic Filler metals are often used to weld Martensitic stainless steel (308, 309, 310)
* Ductile like a rubber band
Filler metal is low strength and high ductility so it will plastically deform and reduces the
stress in the HAZ
Duplex Stainless steel
- Mixture of errite and Austenite (typ ≈ 50/50)
- Low carbon < 0.03%
Avoids carbide precipitation
- Strengths ≈ 2 times Austenitic Stainless Steel
- Weldability issues include:
Loss of toughness due to grain growth of Ferrite phase
Potential for stress corrosion cracking if Ferrite/Austenite balance is wrong
Precipitation Hardened Stainless steel
- 17-4PH, 17-7PH
- Hardened by Precipitation Hardening heat treatment
- Good weldability but must be reheat treated to restore mechanical properties in the HAZ
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ALUMINUM ALLOYS
Physical Properties:
Low density (Al≈2.7 g/cm³ or 0.098lb/IN³) (Mg≈1.7g/cm³, e≈7.8g/cm³)
Modulus of elasticity (Al≈10.5X10⁶ PSI, Steel≈ 30X10⁶ PSI, Ti≈18X10⁶ PSI)
Low melting temperature (Al≈660 ˚C, 1220 ˚ ) no change in color when heated
High thermal conductivity (≈6 time that of steel)
Requires higher heat intensity to produce melting
High thermal expansion (≈ 2 time that of steel, ≈6% shrinkage during solidification)
Causes distortion and possible to solidification cracking
High electrical conductivity
Non-magnetic
Chemical Properties:
Highly reactive with oxygen
Forms tenacious oxide film instantly
(15 ˚A thick initially, 25-50 ˚A normal thickness)
1 ˚A=0.000, 000,004 inch
Anodized Al has an oxide layer that is ≈25,000-50,000 ˚A ”1000 times thicker” (see picture
below)
Al2O3 can be remove b y
o Mechanical- stainless steel brush
o Chemical- flux followed by water rinse
Al that has been thermally treated (precipitately
hardened and artificially aged, Annealed, welded etc)
Will also have a thicker oxide layer
Al2O3 is very hard
Al2O3 has high melting temperature (2052 ˚C)
Oxide must be removed; a tempting to weld
removal will result in melting to base metal and Not
Al2O3 this can prevent coalescence
Al2O3 is an excellent electrical insulator
Oxide must be removed to start arc
Al2O3 is porous and will hold moisture and
hydrocarbons
Welding over this will cause porosity in the weld
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Mechanical Properties:
Pure Al has low strength (4KSI Y.S., 43% Elongation)
Moderate strength increase by cold working (up to 40 KSI Y.S.)
Alloying and precipitation hardening can produce up to ≈ 78 KSI Y.S. 10% Elongation)
Modules of Elasticity ≈ 10.5 X 10⁶ PSI
High elastic deflection
Toughness does not decrease will low temperature
Alloy Designations
Wrought alloys use a 4 digit #
1XXX – 8XXX series alloys
1st digit indicates main alloying elements
2XXX, 6XXX and 7XXX alloys can be precipitation
Hardened to increase strength
1XXX, 3XXX, 5XXX can be work hardened to increase strength
Temper Designations F- As fabricated (no control over strength) O- Annealed H- Strain hardened W- Solutionized T- Precipitation hardened
Preparation of Aluminum for Welding
Storage- store on edge vertically with space between pieces to prevent moisture from collecting
on the surface
Prevents forming a thicker oxide layer
metal working- plasma arc cutting is the most common
(Thicker sections can be prone to solidification cracking on the cut surface)
cleaning- amount of cleaning required is based on how clean the metal is kept prior to welded
and thermal history “ how thick is the oxide layer”
solvents – are used to remove grease and oils
deoxidizers – are available to remove thick oxide layers
(Must be removed completely to avoid corrosion issues)
Alhuzaim- Metallurgy Page 63
moisture removal – preheat to a max of 150 ˚ to remove moisture
wire brush- use stainless steel wire brush as final cleaning step prior to welding
welding of non-heat treatable Aluminum alloys
(1XXX, 3XXX, 5XXX)
welding these alloys will resulting in loss of strength in the HAZ due to annealing or normalizing
(assuming the alloys was strain hardened prior to welding)
5XXX series alloys are preferred between the have the best match of filler/base/HAZ strength
HAZ width is typically less than ½” but 1” is used for design purpose
Width of HAZ can be reduced with reduced heat input but reduction of strength in HAZ can not
be avoided
Welding precipitation hardened Aluminum Alloys
(2XXX, 6XXX, 7XXX)
Welding will resulting overaging of the HAZ and loss of strength (ductility is unchanged or
increases in the HAZ for most alloys)
The loss of strength that occurs due to overaging of a precipitin hardened alloy is typically larger
(higher % of the alloys base metal yield strength) then the loss of strength that occurs in non-
precipitation hardened alloys.
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Titanium Alloys
Used for two main reasons
1- High strength to weight ratio (specific strength =
)
2- Excellent corrosion resistance
Properties
o Density 4.5 g/cm³ (Al=2.7 g/cm³, Fe= 7.8 g/cm³, Mg=1.7 g/cm³)
o Melting temperature 1671
Crystal Structure → HCP up to 883 , BCC above 883
- Modulus of Elasticity 18 10 PSI
- Expensive because it is difficult to refine its natural from (TiO₂)
Alloy Designations
- Industry standard is to use elemental symbols with numbers to indicate a mount of alloying
elements Example Ti-6AI-4V
4 maim Types of Ti Alloys
1) Commercially Pure Ti
- Use for their excellent corrosion resistance ( chemical processing equipment , sursical implants )
- Strengthened by solid solution strengthening
2) Alpha Ti Grades
- Used for cryogenic Application (Ti-5AI-2.5 SN )
- Strengthened by solid solution
- Good weldability for Ti
3) Alpha _ Beta Alloys
- Mast widely used type of Ti ( Ti- 6AI – 4V ) & ( Ti -3Ai -2.5 V ) → ≈ 80% of all Ti used
- Used in Automotive , Aerospace ,and sporting goods
- Precipitation Hardened
- For weldability
4) Beta Alloys
- Used for high strength fasteners ( not typ. Welded )
Alhuzaim- Metallurgy Page 65
Magnesium Alloys
- Density 1.7 g/cm³
- Melt temp 650
- Modulus of Elasticity 6.5× 10⁶ PSI
- High Thermal expansion
- High mechanical pumping Capacity
- HCP crystal structure → Brittle
- Poor fatigue & Impact strength
- Excellent machinability & Castability
- Good weldability
Alhuzaim- Metallurgy Page 66
Chapter 4 Welding Design
Example 1:
Calculate the weight of the above fillet weld the metal is mild steel.
we can use the welding symbol to help us find what essential information to calculate the weight like
the leg size and the length of the weld, as it shown in the drawing the leg size is 5/16 inch and it mention
only one size that’s mean the leg size is equal. Also the length of weld is 12 inch. The density of all steel
is 0.283 lbs/in³. So now we can start following the steps above.
Step 1
Fillet weld CSA = .5 X Base X Height Fillet weld CSA = .5 X .3125 X .3125 = .049 in²
Step 2
Fillet weld Volume = CSA X Length of weld Fillet weld Volume = 0.49 X 12 = .59 in³
Step 3
Fillet weld weight = Volume X density of steel Fillet weld weight = .59 X .283 = .17 lb
To find the weight of an equal leg fillet weld we need
to find the Cross Section Area “CSA”, the length of
the weld and the density of the metal. If we take the
drawing 1 as an example and we suppose it’s a mild
steel, flat face, the following steps is how to calculate
the weight of the weld
To find out the CSA for any triangle we have to know
the length of the base and the height of the triangle
and divided by two. The mathematical formula for
the triangle CSA is.
Fillet weld CSA = .5 X Base X Height
After calculating the CSA, we can calculate the
volume of the weld by multiplying the CSA by the
length of the weld.
Fillet weld Volume = CSA X Length of weld
Finally, to find the weight of the weld we should
multiply the volume by the density that will give us
the weight of the weld.
Fillet weld weight = Volume X density of metal
The weight of the fillet weld is
0.17 lb
Alhuzaim- Metallurgy Page 67
Example 2
If we take example 1 and we add reinforcement as
showing in the drawing. Then we need to calculate the
reinforcement separately and then add the flat fillet to
the reinforcement to get the total weld weight.
To calculate the reinforcement we need to calculate the
Face Dimension ”FD” first, we can apply Pythagoras'
Theorem law to get the FD and then we can calculate
the reinforcement CSA.
As we calculated in the first example the weight of the
flat fillet weld is 0.17lb. So we will pursue to calculate
the reinforcement and add the total weight for the weld.
Pythagoras' Theorem
Face Dimension FD= √
FD=√ = .44 in
CSA Convexity = .5 X FD X reinforcement
CSA Convexity = .44 X .125 X .5 = .03 in²
Volume of convexity = CSA X Length
Volume of convexity = .03 X 12 = .36 in³
Weight of convexity = Volume X Density
Weight of convexity = .36 X .283 = .1 lb
Total weight of the weld = weight of fillet weld + weight of reinforcement
Total weight of the weld = 0.17 + 0.1 = 0.27lbs
Alhuzaim- Metallurgy Page 68
Example 3
To calculate the weld weight in a single bevel pipe we can divide the
weld into three areas as showing in the third drawing. The root
opening and the thickness of the material will be area 1, the bevels will
be area 2, and the reinforcement will be area 3. First we calculate the
Cross Sectional Area for all three areas.
-CSA1 is basically rectangle where the area is the width by the height
CSA1 = root opening X thickness
CSA1 = .125” X .625 = .08 in²
-CSA2 is two triangles where the area is (.5 X the height X base). We
can calculate the height by subtracting the thickness from the root
face. To calculate the base which is the side opposite in the triangle we
can use TAN the height or the side adjacent.
CSA2 = thickness - root face X {(thickness – root face) X tan (
)} X .5 X 2
CSA2 = .625 - .125 X {(.625 - .125) X tan 30} X .5 X 2 = .15 in²
-CSA3 to calculate the reinforcement area we have to calculate the
face dimension first and that by calculating the side opposite and
multiply it by 2 and add the root opening to it.
Face Dimension = (side opposite X number of bevel) + root opening
Face Dimension = (.5 X tan 30 X 2) + .125 =.685 in
CSA3 = Face Dimension X Reinforcement X .5
CSA3 = .685 X .125 X .5 = .04 in²
We add the CSAs to get the total area of the weld
∑ CSA = CSA1 +CSA2 + CSA3 = .08 + .15 + .04 = .27 in²
Finally to calculate the weight we need to calculate the length of the
weld. Since it’s a pipe we need to calculate the circumstance which
(𝝅 X Diameter) then we multiplying it by the density of the steel which
is .283 lbs/in³.
Weight of the weld = CSA X (𝝅 X Diameter) X density
Weight of the weld = .27 X (.3142 X 6”) X .283 = 1.4 lbs
Alhuzaim- Metallurgy Page 69
Example 4
To calculate the weight of the weld in double v groove basically solve
for single V and then divided by two.
Given:
V groove weld both side plate thickness = .625”
Total root face = .125” , root opening = .067”
Included angle = 75 degree , con vex reinforcement = .067”
Consumable density= .1 lbs/in³, weld length=14”
Solution
Total CSA of the weld
CSA1 = Root Opening X thickness = .067 X .625 = .042 in
FD= Tan (37.5) X (T/2 – Root Face/2) = .767 X ( .3125 - .0625)= .192
CSA2 =.5 X .192 X .25 = 025 in² X 4 = .096 in²
CSA3 = .5 X Face Dimension X Reinforcement
CSA3 = .5 X ( .192 + .067 + .192 ) X .067 = .015 in² X(2) = .03 in²
Total volume of the weld
V= CSA X Length = .168 X 14 = 2.35 in³
Total weld weight = Volume X Density
Total weld weight =2.35 X.1 = .235 lbs
Alhuzaim- Metallurgy Page 70
Weld Cost
To calculate the cost for any process we need to find some given information. Same in the welding
process to find the cost of welding we need to know some essential information before we can proceed
to calculate our cost. The cost of weld will be calculated into two ways. First we can calculate the cost
per foot of weld and that will give us good understanding in estimating the cost for big project such as in
construction. Second the calculation of weld per part which can be used in manufacturing a smaller part.
The essential information could be calculated or measured in the work floor. Such as the weld time, the
time spent to load or unload or idle time, travel speed, labor cost, gas cost and consumable cost and so
on. For better understanding we will solve an example.
Example 1:
Find the cost of the welding process per foot and per part. Use the given information below.
Travel Speed (S) = 24 IPM, Fillet Weld Leg Size (LS) = 7/16, Consumable Cost (W) =65 ¢/lb
Idle Time (T) = 120 sec, Labor Cost (L) = 40 $/HR, Welding Length (WL) = 20”, Gas Cost = 3.5 $/HR
Consumable Density (D) = .283 lbs/in³,Process Efficiency (E.2) = .95, Process: GMAW
ANSWER
Welding Time (WT) =
= 50 Sec
Operation Factor (OF) =
Total Time (TT) = WT + T = 50 + 120 = 170 Sec
Welding Volume = .5 X LS X LS X Weld Length = .5 X .4375 X .4375 X 12 = 1.15 in³/ft
Weld weight (J) = WV X D = 1.15 X .283 = .33 lbs/ft
Consumable Cost/foot (CC) =
= 22.2 ¢/ft
Labor and Overhead (LEO) =
Gas Cost (GC) =
= 2.9 ¢/ft
Process Weld Cost per Foot
PWCF = (115 + 22 + 3) = 140 ¢/ft
Process Weld Cost Per Part
PWCP =(
) X PWCF =
(140) = 233 ¢/part OR 2.33 $/part