The thermal stabilisation of austenite in steel

The aim of this investigation was to examine the nature of the normal stabilisation of austenite in a 038%C, 1.8% Cr, 0.3% Mo steel. To assist in the investigation a literature review was made of the various theories which exist and experimental work carried out on both ferrous and non-ferrous allows. Initially X-ray diffraction was chosen as a technique for measuring the amount of retained austenite in the steel and this was developed until the required degree of accuracy was attained. Samples of the steel were given different sets of heat treatment conditions and then analysed for austentite content. It was found that the thermal stabilisation characteristics of the steel were similar to those found by other workers. The results indicated that the embryo theory of stabilisation was best in explaining the characteristics of stabilisation. X-ray diffraction samples were thinned down and examined by thing film electron microscopy. It was found that clarification of any of the theories by this technique was not possible for the allow used as the austenite transformed to martensite during the thinning down operation.