Heat Treatment and Work Hardening of Metals

Engineering Studies – P2 Product Engineering – Materials and Manufacturing

This topic investigates the methods used to modify the engineering properties of metals. Key concepts include the heat treatment processes and the effects on properties caused by cold working.

Key Concepts

• Modification of materials using a heating and cooling process
• The effect of carbon content on steel hardening
• The effect of cold working steel alloys on change structure and properties

Discussion Questions

1. What are the processes that might increase the hardness of many metals?
2. What are the processes that might soften many metals?
3. Describe strain hardening/work hardening, including what occurs when metals are deformed during cold rolling, compressing, or elongation.
4. Describe the annealing process of a cold rolled steel and the effect on structure and properties of the steel.
5. Discuss the meaning of these terms;
   • Quenching
   • Recrystallisation
   • Annealing
   • Normalising
   • Hardening
   • Tempering
   • Case hardening
   • Induction hardening
6. Describe both hardening of high carbon steel and the tempering of the hardened steel.
7. Draw the microstructure of a 0.8% C hardened steel.