Effect of Heat Treatments on the Microstructure and Mechanical Properties of GH4169 Superalloy

In this paper,GH4169 alloy was treated by three different heat treatment processes.The microstructure and mechanical properties of GH4169 superalloy under three different heat treatment processes were observed and studied by OM,SEM,the micro-hardness and impact test.The results show that different heat treatment process lead to different precipitation and distribution of δ phase in GH4169 superalloy.δ phase is short rod like or granular precipitates at grain boundaries after HST treatment,while δ phase can be obtained in the grain boundary and crystal after ST treatment.For DA treatment the grain boundary is smooth and no δ phase precipitation can be observed.After HST and ST treatment,the hardness of GH4169 superalloy did not change,the impact strength obviously increased and the fracture mode was transgranular fracture.After DA treatment,the hardness of GH4169 superalloy decreases down to 60% of as-hot rolled,but the impact strength increased by 4.5 times and the fracture mode showes interguanular fracture.