Effect of two heat treating processes on microstructure and typical high-temperature tensile and stress rupture property of DD32 alloy

DD32 superalloy is widely used in the fabrication of complex single-crystal turbine blades. The sophisticated heat treatment encountered during blade preparation can lead to variations in the microstructure and mechanical properties of the alloy. The standard heat treatment and the full heat treatment which the blade receives have been applied to DD32 alloy, and their microstructure, 900 ℃ tensile property, and 1 000 ℃/280 MPa stress rupture property were also investigated. Optical microscopy and electron microscopy were utilized to characterize the microstructures and the fracture morphologies of the alloy under the two distinct conditions. The results show that there is a more pronounced difference in the microstructure in the dendrite core than that in the interdendritic regions. Compared with the standard heat-treated alloy, the fully heat-treated alloy exhibits a slight reduction in tensile strength at 900 ℃, whereas its elongation and reduction of area show no obvious variations. Meanwhile, the stress-rupture life at 1 000 ℃/280 MPa of the fully heat-treated alloy is moderately decreased, accompanied by an increase in elongation and reduction of area. The findings obtained in the present work offer significant references for the design and preparation of complex turbine blades.