마르텐사이트계 스테인리스강의 템퍼 취성과 준안정상에 관한 분석

The martensitic stainless steel has excellent corrosion resistance and higher strength by quenching and tempering heat treatment. It has been widely used as blade material due to these properties. The hardness and impact toughness of martensitic stainless steel depended strongly on tempering temperatures. The 12Cr martensite stainless steel (SS 410) tempered about 540℃ showed temper embrittlement. To know cause of temper embrittlement in terms of phase identification, a detailed analysis of electron diffraction patterns during TEM observations has been carried out on the α-Fe and α-Fe zone axes for temper embrittlement specimen. The double electron diffraction spots at 1/3(211) and 2/3(211) positions were observed. The lattice space between individual diffraction spots was about 3.5 A and this value coincide with three times to α-bcc lattice space (1.17 A). The area which found double diffraction spots was judged metastable “zone” similar to the omega phase and induced embrittlement of SS410 material. (Received January 4, 2021; Revised January 8, 2021; Accepted January 13, 2021)