mtls 4ls -...
TRANSCRIPT
Lecture Schedule• September 11 - Introduction• September 18– Classification of Ferrous Alloys & Grain Nucleation • September 25– Grain Growth and Grain size / strength relationship• October 02– Grain Refinement
• October 09 – Reading week• October 16 – midterm exam• October 23 – Casting Lecture (Jackie Leung, Dofasco)• October 30 – Martensite
• November 06 – Martensite & Bainite• November 13 – Strengthening Mechanisms • November 20 –Precipitation Hardening• November 27 – No Class
• December Exam
World Annual Production of Different Materials
2015 2014 2016
Steel (million tons)
1,665 1,649 1,559
Aluminum (million tons)
57 54 52
Copper (million tons)
18.7 18.5 18.2
Usage is generally higher than production because of recycling
Classification of Ferrous Alloys
< 8 % alloying element
> 8 % alloying element
< 0.25% C 0.25-0.60 % C 0.60-1.4 % C
< 2.0 % C > 2.14 % C
Outline of the Unified Numbering System for Metals
What does this numbering mean?
AISI → American Iron and Steel Institute
SAE → Society of Automotive Engineers
ASTM → American Society for Testing and Materials
UNS → Unified Numbering System
(G41400)
Most widely used – 4 digits format
System of Steel Designations
What is the material we are going to work with?
4140 Steel (C-Cr-Mo-Mn steel)
Mechanical Properties:
Tensile Strength 655 MPaYield Strength 415 MPaElongation 25%Hardness 92 HRB
Chemical Composition %
C Cr Mn SI Mo S P
0.380-0.430 0.80-1.10 0.75-1.0 0.15-0.30 0.15-0.5 0.04 0.035
Applications of 4140 Steel
ShaftGear
Bolts and nuts
Slide
Microstructures to Be Obtained
Initial Characterization
Martensite
TemperedMartensite
Ferrite/Pearlite
Grain refinement:Recrystallization
Perform:• Optical Microscopy• SEM & EBSD• Hardness Testing• Tensile Testing
BainiteDual phase
4140 steel
Materials Prepared for Each Group
1 sheet
18 tensile test samples
Fe-Fe3C phase diagram
1. Peritectic reaction: at 1493C and 0.16% CL+
3. Eutectoid reaction: at 727C and 0.77% C+Fe3C (Pearlite)
2. Eutectic reaction: at 1147C and 4.3% CL+Fe3C(Ledeburite)
1
2
3
Classification of Carbon Steel
Low C Med C High C
Structural steels, bridges, ships, etc.
Razor blades, cutlery, etc.
Cast Irons
Cementite in Fe-C Phase Diagram
Time-Temperature-Transformation (TTT) diagram for plain carbon steel
• Nature of transformation-isothermal or a thermal (time independent) or mixed
• Type of transformation-reconstructive, or displacive
• Rate of transformation
• Stability of phases under isothermal transformation conditions
• Temperature or time required to start or finish transformation
• Qualitative information about size scale of product
• Hardness of transformed products
Use of TTT Diagram
TTT- 4140 Steel (C-Cr-Mo-Mn steel)
• Jominy Test – fast way to do CCT (microstructure & hardness)
Continuous Cooling Transformation (CCT)
CCT- 4140 Steel (C-Cr-Mo-Mn steel)
Use Dilatometry (sensitive change in length of a sample): to determine fraction of phase transformed
Fraction of Phase Transformation Determination on CCT Curves
MTLS 4LS
Lecturer: Xiaogang Li
JHE-248, Tel ext. 21881, [email protected]
TA (Tuesday): Kazi Bhadhon, [email protected] (Wednesday): Maedeh Pourmajidian, [email protected]
Course Website:http://ourgroup.mcmaster.ca/materials/Xiaogang_Li/
Final Report
40%
Final Exam
40%
Test
20%
Mark BreakdownLectures:
Monday 10:30, LSB-130E
Labs:
Tue. & Thu. 2:30- 5:20Thu. 9:30-12:20MSE, JHE 2nd Floor
Office Hours:
Anytime / by appointment
-The Steel Section is 50% of your mark in 4LS
Assessment:1 Midterm test1 group report2-hr final exam (in Dec)
Some References:• “Mechanical Behaviour of Materials” by
William F. Hosford• “Phase transformations in metals and alloys”
by David A. Porter, K. E. Easterling• “Physical Metallurgy Principles” by Robert E.
Reed-Hill, Reza Abbaschian• “Materials Science and Engineering, an
Introduction” by William D. Callister• “Steels: Heat Treatment and Processing
Principles” by George Krauss
• Attend LECTURES !!!
Questions?