Experimental research concerning the thermal shock behaviour of some ion nitriding stainless steels

The main purpose of this work is to investigate the influence of ion nitriding on thermal shock behaviour of two stainless steel grades (austenitic and martensitic). Samples made from the two steel grades were first ion nitrided in dissociated ammonia and H-N-CH mixture and then subjected to thermal shock from 600°C and 500°C by using a home made apparatus. The study put into evidence two different types of crack initiation and crack growth on the two steel grades. Possible mechanisms responsible for such cracking behaviour are also proposed.