Research on Deformation-induced Martensite Content of Austenite Stainless Steel Bellows Based on Magnetism Testing Method

According to magnetism variety of the deformation-induced martensite, the deformation-induced martensite content was tested with MP30E-S type ferrite measurement instrument, for the bellows made of SUS304 and SUS316L austenite stainless steel separately formed by machine-bulge method, and bellows made of SUS304 austenite stainless steel formed by hydraulic pressure with or without solution treatment respectively. The results show that the deformation-induced martensite content greatly depended on the material, relative deformation amount and heat treatment state. The deformation-induced martensite content of SUS316L stainless steel was much less than that of SUS304 stainless steel under the same deformation condition. The deformation-induced martensite content increased with the increase of relative deformation amount, and the deformation-induced martensite content at the wave crest was much more than that at the wave trough. Solution treatment could greatly reduce the deformation-induced martensite content of the bellows.