In-situ Observation of martensite transformation and retained austenite in supermartensitic stainless steel

Martensite transformation of supermartensitic stainless steel during cooling was in-situ observed by using high temperature laser scanning confocal microscopy and X-ray diffraction by Synchrotron radiation. The crystallography of martensite and austenite structure were analyzed which X-ray diffraction spots and electron back scattered diffraction patterns (EBSD). From the test results it could be concluded that the austenite phase is accommodated by rotation less that 3 degree of the crystallite when the martensite transformation is occurred. X-Ray diffraction integration strength of austenite was influenced by the transformation stress immediately after the martensite transformation. We consider that the diffracting power of parent phase of austenite increase during martensitie transformation, because the compression stress is accommodated, and the defect is introduced, resulting in the mosaic structure.