The effects of alloying elements on uniform elongation of 1420 MPa grade tempered martensite

摘要

The effects of alloying elements addition on uniform elongation of tempered martensite has been investigated. Tempered martensite is considered as dual phase structure composed of ferrite matrix and harder second phase: cementite. Cementite volume fraction and morphology were observed by scanning and transmission electron microscopy. Microstrain of ferrite matrix were evaluated by means of X-ray diffraction analysis. Ii was observed that Carbon addition effectively increased uniform elongation. It was explained that high cementite volume fraction contributed to high uniform elongation. It was also observed that Silicon addition increased uniform elongation remarkably. It was considered that Silicon addition led to refinement of cementite and extremely low microstrain of matrix and both of them contributed to high uniform elongation.