Tiekühlung von Werkzeugstählen

Kurzfassung It has been suggested t hat when tool steels are exposed to temperatures around the boiling point of liquid nitrogen (−196 °C) for extended periods some properties of the steel, particularly wear, are improved. Dissenters claim that the improvements are due to statistical variation and cannot be reproduced consistently. he most commonly reported ex- perimental results are for AISI D2 and AISI M2. his review examines the available evidence and suggests a way forward for the debate. It has also been suggested that the colder the sub-zero treatment temperature ater quenching, the greater the amount of the retained austenite that existed at room tem- perature that is converted to martensite. he implication being that the true martensite inish temperature (M f ) is almost al - ways close to or below absolute zero. Others suggest that M f is in the range −80 °C to −120 °C for most steels. Some of the available evidence is reviewed particularly with respect to AISI D2 and AISI M2 and the conclusion drawn that transformation continues until all the austenite is eliminated or absolute zero is reached. n