Heat treatment is a controlled process of heating and cooling metals to alter their mechanical properties, microstructure, and hardness without changing their shape. It is used to enhance strength, toughness, ductility, hardness, wear resistance, and machinability for various industrial applications.
✔ Improve mechanical properties (strength, hardness, toughness).
✔ Enhance machinability and formability.
✔ Relieve internal stresses from welding, casting, or machining.
✔ Increase corrosion resistance and wear resistance.
✔ Prepare metals for further processing (e.g., hardening or softening).
1️⃣ Annealing – Softens metal by heating and slow cooling to improve ductility and reduce hardness.
2️⃣ Normalizing – Similar to annealing but cooled in air to refine the grain structure.
3️⃣ Hardening (Quenching) – Increases hardness by rapid cooling (quenching) in water, oil, or air.
4️⃣ Tempering – Reduces brittleness and improves toughness after hardening.
5️⃣ Case Hardening – Strengthens only the surface while keeping the core soft (e.g., carburizing, nitriding).
6️⃣ Stress Relief Annealing – Reduces residual stresses without altering hardness significantly.
7️⃣ Isothermal Annealing – Produces a uniform fine structure for improved machinability.
8️⃣ Spheroidizing Annealing – Enhances machinability in high-carbon steels by forming spheroidized carbides.