Effect of Heat Treatment on Structure and Properties of Nickel-based Alloy for Ultra-supercritical Unit above 700℃

By changing the temperatures and holding times of solution treatment，a study is carried out on the heat treatment process for a new-type of nickel-based alloy（as-cold-rolled） for ultra-supercritical unit above 700℃.The law of effects of different heat treatment processes on the structure and properties of the alloy is revealed by means of metallographic microscope and scanning electron microscope（SEM）.The results show that as the temperature and holding time of a solution treatment increases，the grain size of the superalloy increases gradually，and its hardness and tensile strength decreases.When solution treatment temperature exceeds 1 100℃，a few strengthened phases such as MC phase precipitates at the grain boundaries and within the grains.When solution treatment temperature exceeds 1 130 ℃ or holding time exceeds 45 minutes，some grains abnornally grow，the inhomogeneity structure increases，and the carbides start to dissolve again.The optimum solution treatment process for the new-type of nickel-based superalloy will be a treatment temperature of 1 100℃and a holding time of 30 minutes.