Mechanical property changes during accelerated thermal aging embrittlement of cast stainless steel, CF-8A

Abstract

Thermal aging embrittlement of cast stainless steel CF-8A was evaluated by using miniature tensile specimens, Small Punch test and microstructural observation. Optical microscopic analysis, SEM and TEM observations have been carried out in this study. Aging phenomena of the ferrite phase has been identified by hardness measurements. With increase in aging time, changes in strength were observed but not in consistent manner. Despite of the decrease in strength after the prolonged aging at 400℃, no noticeable microstructural features were observed except a`` phase precipitation in ferrite by spinodal decomposition. For this material, miniature tensile tests were found to have limited applicability beyond yield strength. Small Punch test and other mechanical tests showed the changes of mechanical properties similar to those of the miniature tensile tests.