Rectification treatments

Some of the unwelcome adverse effects of heat treatment can be rectified by other thermal processes, the most common of which is cryogenic treatment used to remove retained austenite. Another less common rectification is carbon restoration, whereby surface decarburisation is re-carburised by means of exposure to carburising atmosphere. Control is difficult and this rectification is best carried out by gas carburising in sealed quench furnaces. It has also proved possible to de-nitride components by use of vacuum heat treatment. Again, control is difficult and the process time required is lengthy and therefore cost considerations are generally the deciding factor whether rectification is worthwhile.