Mechanism of creep deformation of Alloy 230 based on microstructural analyses

Creep testing of Alloy 230 was performed at 750, 850 and 950 °C under applied stresses equivalent to its 10% and 25% yield strength (YS) values. The results indicate that this alloy satisfied the maximum allowable creep strain of 1% when loaded to 0.10YS level at these temperatures. Microscopic evaluations revealed the formation of second phase particles including superstructures and carbide precipitates as a function of temperature. The enhanced plastic strain at 0.25YS stress level at 950 °C was attributed to dislocation glide, subgrain formation, and recrystallization.