1. The chemical composition equivalent composition control is not in place.
1. The control of chemical equivalents is not in place.
In order to reduce the cost, the average manufacturer controls the lower limit of Ni. Between 8.0-8.2%, when Cr / Ni reaches a certain value, a certain amount of ferrite appears in the structure of the steel. Ferrite is magnetic; at this time, 1050 is used. ~ 1080 ℃ solid solution treatment can completely dissolve ferrite into austenite without magnetic properties.
2. Cold work hardening.
When austenitic stainless steel produces deformed martensite during cold working, deformed martensite increases the strength of stainless steel, while deformed martensite is magnetic. Using solution treatment or even annealing can make the deformed martensite disappear, but the strength of the steel will decrease.