PREVENTION OF PIPE END CRACK OF MARTENSITE STAINLESS STEEL PIPE

摘要

PURPOSE:To prevent low temperature cracks starting from a cut section by air cooling a stainless steel pipe under the martensite transformation ending temperature and then forcibly water cooling it to a temperature which does not exceed the transformation starting temperature even in the temperature rise following on cutting for cutting work. CONSTITUTION:After a martensite stainless steel pipe is cooled by air cooling under a martensite transformation ending temperature, the hardness thereof is not substantially changed even by forced water cooling. Thus, since the martensite stainless steel pipe can be subjected to the forced water cooling after it is air cooled under the martensite transformation ending temperature, it can be water cooled to a safe temperature not exceeding the martensite transformation starting temperature even by the exothermic reaction caused by the cutting work of a friction saw or the like in an extremely short time. Thus, low temperature cracks are effectively prevented and also the cutting work can be quickly performed to dispense with the heat treatment after cutting and improve productivity.