Electron backscatter diffraction analysis on rolling contact fatigue damage around small cracks in fully tempered martensite steel

摘要

Electron back scattering diffraction analysis has been employed to study local deformation gradient resulted from rolling contact fatigue on a SCM420H martensite steel tempered at high temperature. The fatigue tests were carried out for the material installed for an artificial hole. The highest damaged region was detected in the specimen interior where some grains rotated along <111> axis. Cracks grew in the region produced strain gradient, where crack-opening stress component must exist. The crystal rotation typically occurred near grain boundary in the region and resulted in the localized strain incompatibility near grain boundary. Severe localized plastic deformation at crack-tip caused recrystallized fine grains along cracks.