A short‐process powder metallurgy route “vacuum induction melting ‐ plasma rotating electrode process ‐hot isostatic pressing” was employed to manufacture MAR M247 alloy components. A multistage heat treatment process was developed to precisely regulate the precipitate characteristics and mechanical performance of the alloy. Supersolvus solution promoted the dissolution of the γ′ and carbides, thereby broken up the continuous network of prior particle boundaries (PPBs) and eliminated residual dendritic structures to obtain a homogeneous, equiaxed grain structure. Meanwhile, MC carbides were refined from coarse strips to fine granular particles, uniformly distributed at grain boundaries and within grains. Through multistage aging, the γ′ phase evolved into a multiscale structure comprising butterfly‐like γ s ′ and nanosized γ t ′. The synergistic strengthening effect from precipitation strengthening of γ′ and dispersion strengthening of carbides significantly enhanced mechanical performance. The room‐temperature tensile strength and elongation reached 1515 MPa and 26.1%, respectively, which were about 38.4%∼46.2% and 401.9% higher than as‐cast alloy. At 900°C, its tensile strength and elongation reached 759 MPa and 9.1%, corresponding to improvements of 2.6%∼10.6% and 82%. The endurance life at 760°C/724 MPa reached 29 h, over 45% higher than as‐cast, though performance at 980°C/200 MPa was still constrained by PPBs effect and isothermal strength.
Wang et al. (Tue,) studied this question.