austenitilised

Austenitised is a term used in metallurgy to describe steel that has undergone austenitising heat treatment. This process involves heating the material into the austenite phase region and holding at a high temperature long enough to transform its microstructure to austenite and to homogenize composition, often dissolving carbides in the alloy. The purpose is to produce a uniform austenitic structure that can be transformed upon cooling into a harder phase, typically martensite, bainite, or pearlite, depending on the alloy and cooling rate.

The austenitising step is followed by rapid quenching, which changes the austenite into martensite in many steels. The exact temperatures and hold times depend on alloy composition: carbon steels are commonly austenitised in the approximate range of 800 to 950°C (with higher temperatures for certain alloys), while stainless and high-alloy steels are often austenitised at about 1000 to 1100°C to dissolve chromium carbides and ensure full austenitisation. After quenching, tempering may be employed to adjust hardness and toughness.

Austenitised steels are common in tool steels, high-strength structural steels, and austenitic stainless steels. The effectiveness of austenitising hinges on achieving complete transformation to austenite without excessive grain growth or carbide precipitation, both of which can affect subsequent hardening and mechanical properties. The term remains a descriptor of the steel’s condition immediately after the austenitising and before subsequent cooling and tempering.