Evaluation of Methods for Assessment of austenite Grain Size and Grain Coarsening In Al-Treated Steels

摘要

The prior austenite grain size in heat treatable engineering steels is critical to their heat treatment response and subsequent properties. Testing staandards contain a number of methods for assessing grain size. However, McQuaid Ehn (carburising) is proobably the most common method used for material QA assessments, determining the grain size achieved during a carburising heat treatment carried out at a standard temeprature of 925 deg C (teh most common temperature used for carburising). An alternative mehthod,involving quenching to martensite, is being introduced into some material standards and both methods can be adapted for assessment of grain coarsening characteristics. However, the results obtaiend from the two methods frequently differ, with the carburising method producing significantly finer grains and higher grain coarsening temperatures.