Stainless steel pipe CA6NM heat treatment process
To ensure high strength, high wear resistance and high corrosion resistance, martensitic stainless steel pipe CA6NM is subjected to have heat treatment. They includes softening treatment, quenching and tempering.
By air cooling after forging rolling martensite can be obtained. The softening treatment likewise to reduce the hardness. And also improve its cutting performance. Meanwhile to eliminate the stress and prevent cracking. Normally have two methods. One is high temperature tempering. The forging is heated to 700-800 ℃, insulation 2- 6 h then air-cooled, the martensite transform to sorbitic, the hardness reduced. After treated the hardness of stainless steel pipe 410 is 170一200 HBS. Stainless steel will be 200-230 HBS. The another one is fully annealed which means heat the forging to 840一900℃, insulation 2-4h, cooling down to 600℃ with the speed greater than or equal to 25℃/h, then air-cooled. The hardness of stainless steel pipe CA6NM will be reduced to below 170HBS and stainless steel pipe 430 will be reduced to below 217HBS.
Quench of martensitic stainless steel pipe CA6NM: carbides dissolved gradually accompany with the quench temperature rise. Corresponding increases in hardness after quenching. For 3Crl3 & 4Cr13 the temperature should be higher to ensure full dissolution of carbides because of higher carbon content. Normally the heat range is 1000一1050`C. For stainless steel pipe the lower range and for stainless steel pipe 430 high range.