A Study on the Physical Structure and Residual Stress of Forgings by Vacuum Induction and Atmosphere Protection

Abstract

GH4169 alloy was prepared by vacuum induction, atmosphere protection and vacuum self-consumption triple-smelting-technology. After forging and standard heat treatment, the microstructure defects of GH4169 alloy bar were analyzed by scanning electron microscope and x ray diffraction. The change law of tissue defects was simulated by statistical analysis. Residual stress of GH4169 bar is measured by drilling method, and strain release coefficient is calibrated by finite element analysis. The experimental results show that the GH4169 alloy forgings have fine grain size, including δ phase, γ’ phase, γ’” phase and mc carbide phase. The distribution of small defects near the center is dense, the distribution of large defects near the edge is sparse, but the distribution of large defects near the outermost layer is also very dense. The residual stress increases first and then decreases along the radial direction, and the residual stress shows the trend of “external pressure internal pull” on the disk surface, and the compressive stress increases greatly near the edge of the disc. The residual stress is consistent with the density of tissue defects.