热处理制度对IN718变形合金组织和性能的影响

Effect of heat treatment on microstructure and mechanical properties of IN718 deformed alloy

考察了热处理工艺和长时时效对IN718变形合金组织性能的影响。结果表明:固溶时间为1 h时,960℃固溶处理对合金的晶粒度和δ相特征均无明显影响,然而固溶时间延长至2 h,晶内开始析出δ相,且δ相含量急剧增加。经1040℃固溶处理1 h,δ相完全溶入基体且晶粒显著粗化。在720℃直接时效8 h对合金的组织特征无明显影响,但680℃,100 h长时时效过程中δ相含量随时效时间增加明显增加。合金的性能与析出相特征显著相关,晶界少量δ相的析出提高合金强度和塑性,然而晶内的γ″相转变成针状δ相使屈服强度和晶界调节塑性变形能力下降。经960℃,保温1 h的固溶热处理使合金的晶内强度和晶界强度达到良好的匹配,可以在保持塑性的同时提高合金强度。

The effects of different heat treatments and long-term aging on microstructure and properties of IN718 deformed alloy were investigated.The results show that after solid solution treatment at 96022 for 1h,the grain size and characteristics of 8 phase have no obvious change.However,when the solid solution time increased to 2h,the amount of 8 phase increases significantly and 8 phase can be observed inside'the grain.The 8phase dissolves into the matrix completely,and the grain size grow up after solid solution treatment at 10402 2for 1h.The microstructure isn't influenced significantly when direct aged at 72022 for 8h,but the 8phase increase with the aging time during long aging at 68022 for 100h.The properties of alloy are correlate with the characteristics of precipitated phase,a small amount of 8 phase located in grain boundary can enhance the strength and plasticity of IN718 alloy.The yield strength and the ability of grain boundary adjust plastic deformation decrease with the transformation from "phase to 8phase inside grain.After solid solution treatment at 96022 for 1h, the alloy obtain a favorable match between the grain strength and intragranular strength,which could improve the strength and not decrease the plasticity obviously.