仿钎焊处理对GH4738合金γ′相析出及力学性能的影响

Effect of Brazing-Like Heating on γ′ Precipitation and Mechanical Properties of GH4738 Alloy

通过比较标准热处理和仿钎焊处理后的GH7438合金组织,以及其拉伸和持久性能的变化规律,研究了仿钎焊处理对GH438合金γ′相析出和力学性能的影响.结果表明,经1 040℃保温10min仿钎焊处理,GH4738合金在室温拉伸和540℃拉伸屈服强度降低130MPa以上,抗拉强度也明显降低.同时在730℃下应力为550MPa,其持久寿命也明显降低.组织分析发现,1 040℃保温10min仿钎焊处理导致部分γ′相过度长大,在其周围形成无γ′相析出的低强度区,因此拉伸屈服强度显著降低.同时,γ′相过度长大导致随后时效过程中析出的小γ′相稳定性降低,其在持久过程中迅速长大,会降低其持久寿命.

By comparing the regularity of microstructure,tensile and stress rupture properties of GH7438 alloy after standard heat treatment and brazing-like heating,the effect of brazing-like heating on the precipitation and mechanical properties ofγ′phase of GH438 alloy was studied.The results show that after 10 minutes incubation at 1 040℃imitation brazing,the room temperature tensile yield strength of GH4738 alloy and the tensile yield strength at 540℃are reduced by more than 130 MPa,and the tensile strength is also significantly decreased.The stress at 730℃is 550 MPa and the longevity is also significantly reduced.The results of tissue analysis show that the brazing-like heating treatment at 1 040℃for 10 min resulted in excessive growth of part of theγ′phase,and a low-intensity zone where noγ′phase precipitated was formed around it,so the tensile yield strength was significantly reduced.The excessive growth of theγ′phase leads to a decrease in the stability of the smallγ′phase precipitated during the subsequent aging process;it grows rapidly during the creep rupture process,and reduce the creep rupture life.