mtls 4ls -...

MTLS 4LS

Instructor: Xiaogang Li PhDOffice: JHE 248Ext. 21881Email: Lixiaog@mcmaster.ca

Sept. 2017

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, Lixiaog@mcmaster.ca

TA (Tuesday): Kazi Bhadhon, bhadhokm@mcmaster.caTA (Wednesday): Maedeh Pourmajidian, pourmam@mcmaster.ca

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?