LONG-TERM CREEP STRENGTH PROPERTY AND MIC ROSTRUCTURAL STABILITY OF 12CR STEEL

Heat-to-heat variation of long-term creep strength property observed f or 12Cr steel was investigated from viewpoints of creep deformation be haviour and stability of microstructure. Heat-to-heat variations of cr eep deformation behaviour and creep rupture strength properties were d escribed by the differences in the parameter Lu in alpha modified thet a projection method which indicates the acceleration in creep rate at the tertiary stage. It was shown that the magnitude of alpha and its c hange with creep depend on the morphology and stability of initial mic rostructure, and correlate with microstructural changes accompanied by recovery and recrystallization under tertiary creep. It is concluded therefore that the creep strength and rupture life can be controlled b y the microstructure and its stability of 12Cr steels and expressed on ly by the rate constant alpha.