Annealing

Annealing reduces hardness, improves ductility, relieves stress or modifies microstructure. Full annealing, process annealing, spheroidizing and solution annealing serve different steel families.

Normalizing

Heating above the transformation range followed by air cooling refines grain structure and can improve strength/toughness uniformity in many carbon and low-alloy steels.

Quenching

Rapid cooling forms hard martensitic structures where composition and section size provide sufficient hardenability. Water, polymer, oil, gas and other quench media provide different cooling severity.

Tempering

Tempering quenched steel reduces brittleness and adjusts hardness, strength and toughness. Temperature and time strongly influence final properties.

Case hardening

Carburizing, carbonitriding, nitriding and induction/flame hardening produce a hard wear-resistant surface while retaining a tougher core.

Stainless and precipitation hardening

Austenitic and duplex stainless steels commonly use solution annealing; martensitic stainless is quenched and tempered; precipitation-hardening stainless uses solution treatment plus controlled aging.

Engineering controls

Always control heating rate, soak temperature/time, atmosphere, quench medium, distortion, hardness verification and post-treatment inspection according to the grade and applicable procedure.