HEAT TREATMENT OF METALS Annealing Martensite Formation in Steel Tempering John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Annealing Heating and soaking metal at suitable temperature for a certain time, and slowly cooling Reasons for annealing: Reduce hardness and brittleness Soften metals Recrystallize cold worked metals Relieve residual stresses Full annealing Normalizing John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Martensite Formation in Steel Equilibrium is prevented under rapid cooling Austenite transforms into a nonequilibrium phase called martensite Martensite is hard and brittle Austenite - face‑centered cubic (FCC) Martensite - body‑centered tetragonal (BCT) John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Iron-Carbon TTT curve Cooling trajectory (0.80% C) Iron‑carbon phase diagram John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Hardness of Plain Carbon Steel Tempering to relieve stress in Martensite structure John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Quenching Media and Cooling Rate Brine -salt water Agitated brine (fastest cooling rate) Still fresh water Still oil Air (slowest cooling rate) Fast cooling rate Internal stresses Distortion Cracks John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

SME Video John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Materials in Manufacturing Metals Ceramics Polymers Composites Venn diagram John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

Properties of Composites - Rule of Mixtures f=fraction m=mass =density V=volume subscripts c=composite m=matrix r=reinforcing phases John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

SME Video John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

ASSIGNMENT – STUDENT MUST SHOW SOLUTION TO PROFESSOR DURING LAB PERIOD What is the resistance R of a length of copper wire whose length = 20 m and whose diameter = 0.10 mm? Hints: Resistivity value r from table Convert diameter to m John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing