steel process and element detail.docx

7/30/2019 Steel Process And Element Detail.docx

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Hardness and Tensile Strength

1Kgf/mm2 = 9.804 N/mm2

Tensile strength and the equivalentsIn Brinell, Rockwell and Vickers

Tensilestrengthkg/mm2

Brinellhardness

Hb

Rockwell100 kg

Rb

hardness150 kg

Rc

Vickershardness

Hv


Brinellhardness

Hb

Rockwell100 kg

Rb

hardness150 kg

Rc

Vickershardness

Hv

28 78 38 - 78 71 197 92 12 197

29 81 41 - 81 72 200 93 13 202

30 83 43 - 83 73 203 93 14 204

31 86 45 - 86 74 206 94 14 207

32 88 47 - 88 75 209 94 15 210

33 92 49 - 92 76 211 95 16 21234 95 51 - 95 77 214 95 16 214

35 97 53 - 97 78 216 96 17 217

36 100 55 - 100 79 219 96 17 220

37 103 57 - 103 80 222 97 18 223

38 106 59 - 106 81 225 97 19 225

39 108 61 - 108 82 228 98 19 229

40 111 63 - 111 83 230 98 20 231

41 114 64 - 114 84 233 99 21 234

42 116 65 - 116 85 236 99 21 237

43 120 67 - 120 86 239 100 22 239

44 123 69 - 123 87 243 100 22 243

45 125 70 - 125 88 246 - 23 246

46 127 71 - 127 89 248 - 23 248

47 130 72 - 130 90 250 - 24 250

48 133 73 - 133 91 253 - 25 254

49 137 75 - 137 92 255 - 25 258

50 139 76 - 139 93 258 - 26 262

51 141 77 - 141 94 261 - 26 265

52 145 78 - 145 95 264 - 27 267

53 147 79 - 147 96 266 - 27 269

54 149 80 - 149 97 268 - 27 271

55 153 81 - 153 98 271 - 28 274

56 156 82 0 155 99 275 - 28 280

57 159 83 1 158 100 278 - 28 283

58 161 83 2 160 101 281 - 29 285

59 164 84 3 165 102 283 - 29 28760 167 85 4 167 103 288 - 29 291

61 170 86 5 170 104 291 - 30 297


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62 173 87 6 174 105 295 - 30 299

63 175 87 6 175 106 297 - 31 302

64 178 88 7 178 107 299 - 31 305

65 181 89 8 181 108 302 - 31 308

66 184 89 9 185 109 306 - 32 311

67 187 90 9 187 110 308 - 32 313

68 189 91 10 189 111 310 - 33 315

69 191 91 11 191 112 312 - 33 317

70 195 92 12 195 113 315 - 34 320


Brinellhardness

Hb

Rockwellhardeness

100 kgRb

VickershardnessHv


BrinellhardnessHb

Rockwellhardeness100 kgRb

Vickers hardnessHv

114 316 34 321 157 436 46 450115 320 34 325 158 439 46 453

116 323 35 329 159 441 46 456

117 325 35 331 160 444 47 459

118 328 35 334 161 447 47 461

119 331 35 336 162 450 47 465

120 334 36 340 163 452 48 468

121 336 36 343 164 456 48 472

122 339 36 345 165 459 48 475

123 342 37 349 166 461 48 477

124 345 37 352 167 464 49 480

125 346 37 355 168 466 49 483

126 350 38 358 169 469 49 486

127 353 38 360 170 472 49 489

128 356 38 364 172 477 50 494

129 359 39 367 174 484 50 502

130 362 39 369 176 489 50 508

131 364 39 371 178 494 51 512

132 367 39 375 180 500 51 520

133 369 40 378 182 506 52 526

134 372 40 382 184 511 52 532

135 375 40 385 186 517 53 539

136 378 40 388 188 522 53 545

137 380 41 390 190 527 54 551

138 383 41 393 192 532 54 555

139 386 41 396 194 539 55 564

140 389 42 399 196 544 55 569141 392 42 402 198 550 56 576

142 395 42 405 200 556 56 582


3/12

143 397 42 408 205 570 .57 597

144 400 43 411 210 583 58 613

145 402 43 413 215 597 59 629

146 405 43 416 220 611 60 642

147 407 43 419 225 625 60 661

148 411 44 423 230 639 61 679

149 413 44 425 235 651 62 695

150 416 44 428 240 668 63 718

151 419 44 430 245 682 64 736

152 422 45 434 250 695 65 754

153 424 45 438 255 709 66 771

154 428 45 440 260 722 67 790

155 431 45 444 265 736 68 812

156 433 46 447 270 750 69 839

SHEET METAL GAUGES

Thickness in inches and Millimetres

No. Standard wire gauge Birmingham gauge

in. mm in. mm

15/0 - - 1.000 25.414/0 - - 0.9583 24.34

13/0 - - 0.9167 23.28

12/0 - - 0.8750 22.22

11/0 - - 0.8333 21.17

10/0 - - 0.7917 20.11

9/0 - - 0.750 19.05

8/0 - - 0.7083 17.99

7/0 0.500 12.700 0.6666 16.93

6/0 0.464 11.786 0.625 15.885/0 0.432 10.973 0.5883 14.94

4/0 0.400 10.160 0.5416 13.76

3/0 0.372 9.449 0.500 12.70

2/0 0.348 8.839 0.4452 11.31

0 0.324 8.230 0.3964 10.07

1 0.300 7.620 0.3532 8.971

2 0.276 7.010 0.3147 7.993

3 0.252 6.401 0.2804 7.122

4 0.232 5.893 0.250 6.3505 0.212 5.385 0.2225 5.652


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6 0.192 4.877 0.1981 5.032

7 0.716 4.470 0.1764 4.481

8 0.160 4.064 0.1570 3.988

9 0.144 3.658 0.1398 3.551

10 0.128 3.251 0.1250 3.175

11 0.116 2.946 0.1113 2.827

12 0.104 2.642 0.0991 2.517

13 0.092 2.337 0.0882 2.250

14 0.080 2.032 0.0785 1.994

15 0.072 1.829 0.0699 1.775

16 0.064 1.626 0.0625 1.588

17 0.056 1.422 0.0556 1.412

18 0.048 1.219 0.0495 1.257

19 0.040 1.016 0.0440 1.11820 0.036 0.914 0.0392 0.9957

21 0.032 0.813 0.0349 0.08865

22 0.028 0.711 0.03125 0.7938

23 0.024 0.610 0.02782 0.7066

24 0.022 0.559 0.02476 0.6289

25 0.020 0.508 0.02204 0.5599

26 0.018 0.457 0.01961 0.4981

27 0.0164 0.4166 0.01745 0.4432

28 0.0148 0.3579 0.015625 0.396929 0.0136 0.3454 0.0139 0.3531

30 0.0124 0.3150 0.0123 0.3124

31 0.0116 0.2946 0.0110 0.2794

32 0.0108 0.2743 0.0098 0.2489

33 0.0100 02540 0.0087 0.2210

34 0.0092 0.2337 0.0070 0.1956

35 0.0084 0.2134 0.0069 0.1753

36 0.0076 0.1930 0.0061 0.1549

37 0.0068 0.1727 0.0054 0.137238 0.0060 0.1524 0.0048 0.1219

39 0.0052 0.1321 0.0043 0.1092

40 0.0048 0.1219 0.00386 0.09804

41 0.0044 0.1118 0.00343 0.08712

42 0.0040 0.1016 0.00306 0.07772

43 0.0036 0.0914 0.00272 0.06909

44 0.0032 0.0813 0.00242 0.06147

45 0.0028 0.0711 0.00215 0.05461

46 0.0024 0.0610 0.00192 0.0487747 0.0020 0.0508 0.00170 0.04318


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48 0.0016 0.0406 0.00152 0.03861

49 0.0012 0.0305 0.00135 0.03429

50 0.0010 0.0254 0.00120 0.03048

51 - 0.00107 0.02718

52 - 0.00095 0.02413

Chemical Elements

Element Influence

Al Aluminum

A powerful deoxidizer and nitride former. In small amounts, can serve

as a powerful, inexpensive grain refiner ( i.e., restricts Austenitic graingrowth ). Can improve toughness, especially at low temperatures.

B Boron Strongly increases hardenability, by suppressing Ferrite precipitationduring transformation from Austenite during heat treatment. Effectivein very small amounts ( less than 0.003% B ).

Also Boron reduces the brittleness of hardened steel, by having apositive influence on the transformation from Ferrite to Austenite to

Martensite Structure. Especially on steels with lower carbon content(e.g. C=0.27%) that tend to transform inert, Boron strongly improvesthe transformation process.

C Carbon The principal element responsible for hardness in steel, due toformation of Fe 3C upon cooling through the TransformationTemperature, when Gamma Iron ( Austenite ) decomposes into AlphaIron ( Ferrite ) + Fe3C ( Iron Carbide ). Increases tensile strength insteels. Ductility generally decreases as C increases, but in most casesthis effect can be offset with proper heat treatment. Weldabilitydecreases as C increases. Excess oxygen usage may be required to

remove excess C ( takes furnace time ).

Cr Chrome Cr is a strong carbide former, and can improve wear resistance andsomewhat increase resistance to softening during tempering.

Improves hardenability depth. Promotes the response of steelcontaining Cr the effects of carburizing heat treatment. In combinationwith even very low P, Sn, As or Sb contents, Chromium and Ni-Cralloy steels are particularly susceptible to "temper embrittlement" (lossof ductility when tempering or slow cooling in the range 700-1100 F).

When Cr > 4%, corrosion resistance greatly improves ( Responsiblefor corrosion resistance in Stainless Steels ). Not readily oxidized from


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bath; requires high temperatures, increased heat time and slag volume.

Cr makes steel oil and air hardenable.

Mo Molybdenum Mo is a strong Carbide former and has a high effect on

hardenability. Improves control of heat treatment by inhibitingformation of certain microstructures ( e.g., Pearlite ). Can improvehigh temperature corrosion resistance. Can improve toughness &fatique properties. Expensive.

Vanadium V and Molybdenum Mo Both have influence on bettertoughness and have the same negative influence as Cr they are mostlyused as fragility compensatory in High carbon steels like D2 or inextreme cause in 440V steel.

Mn Manganese Mn extremely reduces the critical cooling temperature und increaseshardenability. Yield strength, tensile strength and durability increasewith increasing Mn content. Also Mn has positive impact on forgingand weld ability and increases through hardening.

Ni Nickel Improves harden ability. Reduces distortion in heat treating. Permitsuse of milder quenching media. Improves weldability, plasticity &fatique properties. Improves toughness, especially at low temperatures.Improves corrosion resistance.

P Phosphorus Phosphor P and Sulfur S: these elements are necessary intrusionscaused by metallurgic process. They are undesirable and their contentshould be less than 0,025 %.

S Sulphur Phosphor P and Sulfur S: these elements are necessary intrusionscaused by metallurgic process. They are undesirable and their contentshould be less than 0,025 %.

Si Silicon Si is an element (like Mn) that is contained in every kind of steel sincealready iron ore has a certain amount. In content up to 0,5% it has

positive influence on mechanical properties and helps to perform hotforming of steel. Si deoxidizes and increases durability and stronglyincreases elasticity. Only steel with more than 0.40% is called siliconsteel.

WTungsten Forms extremely hard, stable carbides. Used almost exclusively in

High Speed and other tool steels (requiring wear resistance and highhot hardness). Very expensive. Used in the manufacture of High SpeedTool Steel, but otherwise almost never used due to extremely highcost.

V Vanadium Vanadium V and Molybdenum Mo Both have influence on bettertoughness and have the same negative influence as Cr they are mostly


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used as fragility compensatory in High carbon steels like D2 or inextreme cause in 440V steel.

V is an effective grain refiner ( i.e., restricts Austenitic grain growth ).Strong carbide and nitride former ( improves abrasion resistance). Improves yield strength, toughness and hot hardness. Stronglyincreases resistance to softening during tempering. Expensive.

Microstructure

Austenite

This phase is only possible in carbon steel at high temperature. It has aFace Centre Cubic (F.C.C) atomic structure which can contain up to 2%carbon in solution.

Ferrite

This phase has a Body Centre Cubic structure (B.C.C) which can hold verylittle carbon; typically 0.0001% at room temperature. It can exist as either:alpha or delta ferrite.

Cementite

Unlike ferrite and austenite, cementite is a very hard intermetalliccompound consisting of 6.7% carbon and the remainder iron, its chemicalsymbol is Fe3C. Cementite is very hard, but when mixed with soft ferritelayers its averidge hardness is reduced considerably. Slow cooling givescourse perlite; soft easy to machine but poor toughness. Faster coolinggives very fine layers of ferrite and cementite; harder and tougher

Pearlite

A mixture of alternate strips of ferrite and cementite in a single grain. Thedistance between the plates and their thickness is dependant on the coolingrate of the material; fast cooling creates thin plates that are close togetherand slow cooling creates a much coarser structure possessing lesstoughness. The name for this structure is derived from its mother of pearlappearance under a microscope. A fully pearlitic structure occurs at 0.8%Carbon. Further increases in carbon will create cementite at the grainboundaries, which will start to weaken the steel.

Martensite

If steel is cooled rapidly from austenite, the F.C.C structure rapidlychanges to B.C.C leaving insufficient time for the carbon to formpearlite. This results in a distorted structure that has the appearance of fineneedles. There is no partial transformation associated with martensite, iteither forms or it doesn't. However, only the parts of a section that coolfast enough will form martensite; in a thick section it will only form to acertain depth, and if the shape is complex it may only form in smallpockets. The hardness of martensite is solely dependant on carbon content,it is normally very high, unless the carbon content is exceptionally low.

Hardness Test


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Hardness test: A test of hardness usually by determining the resistance of the material toindentation under standard conditions.

The following are established methods of hardness testing :-

Brinell hardness test: A test to determine hardness by pressing a hard steel ball of knowndiameter under a standard load into the surface of the material and measuring the diameter ofthe indentation produced. The Brinell hardness number, BHN = Load in kg / Spherical area ofimpression in sq. mm.

Rockwell hardness test: Determines hardness by indicating on a dial the depth of theimpression caused by a loaded indenter in the form of either a diamond cone (Scales A and C)or a hardened steel ball (Scale B). When the load is removed, the dial gauge recordes the depthof impression in terms of Rockwell numbers.

Vickers pyramid hardness test: When the Brinell test is used on very hard materials, low

values result owing to the spherical shape of the indenter and flatening of the ball. These areeliminated by using a square based diamond pyramid indenter which does not deform easilyand gives geometrically similar impressions under various loads. The diamond pyramid with anangle between opposite faces of 136 degree is pressed under a standard load into the surface ofthe material, and the diagonal of the indentation produced is measured- The load divided by thecontact area of impression gives the Vickers Pyramid Number. VPN = Load in kg / Pyramidalarea of impression in sq. mm.

ooling: Cooling a plate with water immediately following the final rolling operation. Generallythe plate is water cooled from about 1400F to approximately 1100F.

Ageing: A change in properties that may occur gradually at atmospheric temperatures (naturalageing) and more rapidly at higher at higher temperatures (artificial ageing).

Age Hardening: The hardening of steel induced by ageing.

Alloy Steel: Steel is considered to be an alloy steel when either (1) the maximum of the rangegiven for the content of alloying elements exceeds one or more of the following percentages:manganese 1.65, silicon 0.60, copper 0.60; or (2) a definite range or definite minimum quantityof those elements considered alloys is specified. For example, chromium, molybdenum andnickel.

Annealing: Heating to holding at a suitable temperature, followed by cooling at a suitable rate,for such purposes as:

1. inducing softness2. improving machinability3. improving cold working properties4. obtaining a desired structure5. removing stresses

When applicable, the more specific terms, full annealing, isothermal annealing or sub-criticalannealing could be used:-

1. Full annealing. Heating to and holding at some temperature above the transformationrange, followed by cooling slowly by the transformation range.


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2. Isothermal Annealing. Heating to and holding at some temperature above thetransformation range, then cooling to and holding at a suitable temperature until theaustenite to pearlite transformation is complete, and finally cooling freely.

3. Sub-Critical Annealing. Heating to and holding at some temperature below thetransformation range, followed by cooling at a suitable rate.

Austenitizing: The process of forming the austenite phase by heating a ferrous alloy into thetransformation range (partial austenitizing above the lower critical temperature) or above thisrange (complete austenitizing above the upper critical temperature).

Bainite: A decomposition product of austenite consisting of an aggregate of ferrite andcarbide. In general, it forms at temperatures lower than those where very fine pearlite forms,and higher than those where martensite begins to form on cooling.

Blue Annealing: Sub-critical annealing of bright steel during which the surface becomesoxidized to a blue temper colour by the controlled admission of air and/or steam.

Blued Edges: Edges of sheet or strip which have become coloured due to slight oxidationduring the heat treatment.

Carbon Steel: A steel the properties of which are determined mainly by the percentage ofcarbon present.

Chamfering: The removal of sharp edges. The term is practically synonymous with bevellingbut has a less a restricted application.

Cold Reduction: Reducing the thickness of steel sheet or strip to the finished gauge by heavy

cold working between rolls.

Cold Rolling: Passing sheet or strip at room temperature between a pair of rotating rolls. Thereduction in thickness may be very bright, as in the finishing process applied to hot rolledsheets, or heavy as in the cold rolling of narrow strip.

Cold Working: The operation of permanently altering the shape or dimensions of the steel,carried out at atmospheric temperature by, for example, cold rolling or cold reduction. Othermethods of applying cold work are by drawing, pressing, forming, bending, swaging,etc.

Corrosion Fatigue: Fatigue accelerated by simultaneous corrosion.

Creep: Plastic deformation which proceeds slowly and continuously when stress is applied atelevated temperatures. In steel, creep is negligible below about 300 degree centigrade.

Critical Grian Growth: A drastic enlargement of the grains when certain steels, particularlylow carbon steels, are subjected to a certain small amount of cold work and then annealed at atemperature below the upper critical point.

Decarburization: The loss of carbon from the surface of steel as a result of heating in amedium that reacts with the carbon.

Deoxidation: A process used during melting and refining of steel to remove and/or chemicallycombine oxygen from the molten steel to prevent porosity in the steel when it is solidified.


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Ductility: Ability to undergo cold plastic deformation usually as a result of tension.

Elasticity: The property of the material by which it returns to its original dimensions after theremoval of a stress.

Elastic Limit: The highest stress that can be applied without producing permanentdeformation.

Elongation: The increase in length of a tensile test piece when stressed. The elongation atfracture is usually expressed as a percentage of the original gauze length.

Etching: Treatment of prepared metal surfaces with acid or other reagents which, bydifferential attack, reveal the structure.

Fatigue: The tendency to fracture by means of a progressive crack under repeated alternatingor cyclic stresses considerably below the tensile strength.

Ferrite: The room temperature form of alpha iron, one of the two major constituents of steel(cementite) in which it acts as the solvent to form solid solutions with such elements asmanganese, nickel, silicon and, to a small degree, carbon.

Grain Growth: A coarsening of the crystal structure under certain conditions of heating. Thisshould not be confused with critical grain growth.

Hardness: Resistance to deformation, indentation, abrasion, cutting, etc.

Hardness Test: A test of hardness usually by determining the resistance of the material to

indentation under standard conditions.

The following are established methods of hardnesss testing :-

Brinell hardness test:A test to determine hardness by pressing a hard steel ball of knowndiameter under a standard load into the surface of the material and measuring the diameter ofthe indentation produced. The Brinell hardness number, BHN = Load in kg / Spherical area ofimpression in sq. mm.

Rockwell hardness test: Determines hardness by indicating on a dial the depth of theimpression caused by a loaded indenter in the form of either a diamond cone (Scales A and C)

or a hardened steel ball (Scale B). When the load is removed, the dial gauge recordes the depthof impression in terms of Rockwell numbers.

Vickers pyramid hardness test- When the Brinell test is used on very hard materials, lowvalues result owing to the spherical shape of the indenter and flattening of the ball. These areeliminated by using a square based diamond pyramid indenter which does not deform easilyand gives geometrically similar impressions under various loads. The diamond pyramid with anangle between opposite faces of 136 degree is pressed under a standard load into the surface ofthe material, and the diagonal of the indentation produced is measured- The load divided by thecontact area of impression gives the Vickers Pyramid Number. VPN = Load in kg / Pyramidalarea of impression in sq. mm

Inclusions (Non-metallic inclusions): Particles of oxides, silicates, sulphides, refractorymaterials, slag, etc., embedded in the metal.


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Internal Stress: Stress produced within the metal by transformation, by temperaturedifferences on heating or cooling, or by mechanical working.

Killing: Applying to finally heat treated narrow strip a small amount of cold work to preventkinks and stretcher strains on further manipulation. Skin passing is the usual method of killing.

Lamination: Separation into two or more layers due to some discontinuity in the steel, usuallya layer of non-metallic inclusions.

Malleability: Capacity for undergoing deformation in all directions, usually cold deformationby hammering or squeezing.

Martensite: A microconstituent or structure in hardened steel, characterized by an acicular orneedle-like pattern, and having the maximum hardness of any of the decomposition products ofan austenite.

Mild Steel: Carbon steel containing approximately 0.12 to 0.25 per cent of carbon.

Mill Edge: The natural edge left when sheet or strip is rolled on the flat surfaces only.

Mill Shearing: Shearing the edges of a mill pack to approximate size.

Pearlite: A microconstituent of iron and steel consisting of a lamellar aggregate of ferrite andcementite (a compound of iron and carbonFe3C).

Quenching & Tempering: A thermal process used to increase the hardness and strength ofsteel. It consists of austenitizing, then cooling at a rate sufficient to achieve partial or complete

transformation to martensite. Tempering involves reheating to a temperature below thetransformation range and then cooling at any rate desired. Tempering improves ductility andtoughness, but reduces the quenched hardness by an amount determined by the temperingtemperature and time.

Pickling: The removal of scale by treatment with diluted acids or other chemicals.

Roll Marks: Periodic surface marks due to some imperfection on the surface of a roll.

Seam: A longitudinal surface defect similar to a roak, except that in a cross rolled sheet such adefect would run transversely.

Sheared Edges: Edges resulting when a sheet or strip is either sheared or slit in rotary cutters.

Sperodized Annealing: A prolonged heating of the steel in a controlled-atmosphere furnace ator near the lower critical point, followed by retarded cooling in the furnaces, to produce alower hardness than can be obtained by regular annealing.

Stress Relieving: A thermal cycle involving heating to a suitable temperature, usually 1000-1200F, holding long enough to reduce residual stresses from either cold deformation or thermaltreatment, and then cooling slowly enough to minimize the development of new residualstresses.


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Stress Relieving (Stabilising): Heating to and, if necessary, holding at, some temperaturegenerally below the transformation range, usually followed by slow cooling, for the solepurpose of relieving internal stresses.

Note:- Other treatments, eg., annealing, tempering, etc., whilst primarily applied to bring aboutchanges in structure or properties may also relieve internal stresses.

Stretcher Strains (Luder lines): A furrowed roughening of the surface of low carbon sheet orstrip due to uneven yielding in the first stages of cold deformation after annealing or, in a lessdegree, after normalising or hot rolling.

Temper: The mechanical condition of strip as controlled by heat treatment and cold rolling.For example, a strip in the finally annealed condition is 'soft temper', whilst strip subjected toheavy cold rolling as the final treatment is 'hard temper'. Between these are the intermediatetempers of which the common ones are 'skin passed', 'quarter hard' and 'half hard'.

Tempering: The carbon trapped in the martensite transformation can be released by heatingthe steel below the A1 transformation temperature. This release of carbon from nucleated areasallows the structure to deform plastically and relive some of its internal stresses. This reduceshardness and increases toughness, but it also tends to reduce tensile strength. The degree oftempering is dependant on temperature and time; temperature having the greatest influence.

Tensile Strength: The maximum load reached in a tensile test divided by the cross-sectionalarea of the gauge length portion of the test piece. Also termed maximum stress or ultimatetensile stress.

Tolerance: The permitted deviation from a specified dimension or weight, usually expressed

as 'plus' or 'minus' on that quantity.

Yield Stress: The stress (load divided by original area of cross-section of a test piece) atwhich, in a tensile test, elongation of the test piece first occurs without increase of load.

steel process and element detail.docx

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