härdningstemperaturen

Härdningstemperaturen, eller hardening temperature, is the temperature at which a metal, especially steel, undergoes a heat treatment process that results in increased hardness. It is the point at which the material changes from austenite to martensite or other hard phases, and is therefore a key parameter in controlling the final mechanical properties.

During austenitisation the metal is heated above the recrystallisation temperature, then rapidly quenched to freeze the high‑temperature structure. The hardening temperature determines how much time the alloy spends in the austenitic region, influencing the amount of retained austenite and the size of the martensitic needles that form.

Typical hardening temperatures vary widely depending on composition. For plain carbon steels they lie between 700 °C and 850 °C. Aluminum alloys harden near 520 °C, whereas high‑strength tool steels may need temperatures up to 950 °C to achieve the desired microstructure.

At the hardening temperature the grain structure becomes refined, and the transition from ductile to brittle behavior depends on the extent of martensite formed. Small changes can dramatically alter toughness and fatigue resistance.

The temperature is measured with thermocouples or infrared pyrometers during the process, and is often calibrated against standard reference points to ensure repeatability across batches.

Reliable determination of the hardening temperature is essential for quality control in manufacturing, enabling parts to meet specifications for wear resistance, cutting performance, and dimensional stability.