MEPX
Chapter 7 of 10All chapters
  1. 1Describing a material
  2. 2Structure decides behaviour
  3. 3Metals
  4. 4Ceramics and polymers
  5. 5Composites
  6. 6How materials fail
  7. 7Processing changes properties
  8. 8Choosing a material
  9. 9Modern materials
  10. 10Materials and sustainability

Chapter 7 of 10

Processing changes properties

The same alloy, different material.

Heat treatment

Heating and cooling at controlled rates changes a metal internal structure. Quenching steel makes it hard and brittle; tempering afterwards trades some hardness for toughness.

  • Annealing softens a work-hardened metal so it can be shaped again.
  • Welding is a local heat treatment, wanted or not, and it changes the metal around the joint.

Forming

Casting, forging, rolling, extrusion and machining each leave a different internal structure. A forged part is usually stronger than a cast one of the same alloy.