后续热处理对激光3D打印GH4099合金微观组织和高温力学性能的影响  

Effects of Subsequent Heat Treatment on Microstructure and High-Temperature Mechanical Properties of Laser 3D Printed GH4099 Alloy

作　　者：赵亚楠 郭乾应 刘晨曦[1] 马宗青[1] 刘永长[1] ZHAO Yanan;GUO Qianying;LIU Chenxi;MA Zongqing;LIU Yongchang(School of Materials Science and Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学材料科学与工程学院,天津300072

出　　处：《金属学报》2025年第1期165-176,共12页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.U22A20172和52122409;国家重点研发计划项目No.2023YFB3712002。

摘　　要：激光粉末床熔融(LPBF)3D打印技术具有跨维度多尺度成形的技术特点,同时表现出非平衡快速凝固的冶金特征,与传统制造工艺形成的微观组织存在明显差异。基于传统制造工艺发展而来的热处理工艺难以适用于LPBF制备的样品,因此,研究LPBF打印件专用的后续热处理制度对于其组织和性能调控具有重要的意义。本工作以LPBF制备的GH4099合金为研究对象,研究了后续热处理对3D打印高温合金非平衡微观组织和高温力学性能的影响。结果表明,固溶处理不仅影响打印组织的再结晶行为,而且也与碳化物和γ'相的析出行为密切相关,因而对GH4099合金的高温延伸率影响较大。LPBF制备GH4099合金中的多尺度异质结构使其组织热稳定性明显高于传统铸锻件,因此需要更高的固溶热处理温度以促进其完全再结晶。经1150℃固溶处理1.5 h后,GH4099打印件中柱状晶转变为等轴晶并形成大尺寸孪晶,同时晶界处M_(23)C_(6)碳化物的析出也受到抑制。在随后的时效热处理过程中,由于再结晶释放了3D打印晶粒内部储存的畸变能,使得基体中γ'相的析出受到了明显抑制。基于上述结果,通过优化热处理制度,GH4099合金打印件实现了高温强度和塑性的良好匹配。The multi-dimensional,multi-scale forming characteristics of laser powder bed fusion(LPBF)3D printing technology,combined with its complex non-equilibrium solidification process,result in multilayered microstructures that differ significantly from those produced by traditional manufacturing methods.However,it is challenging to apply existing heat treatment solutions,developed for conventional manufacturing processes,to LPBF.Therefore,a tailored heat treatment approach is required for LPBFprinted components to regulate their microstructure and properties effectively.This study investigated the modulation mechanism of subsequent heat treatment on the non-equilibrium microstructure and high-temperature mechanical properties of 3D-printed GH4099 superalloy produced via LPBF.The findings reveal that solution treatment influences the recrystallization behavior of the printed microstructure and the precipitation behavior of carbides and γ'phases,which play critical roles in determining the alloy's hightemperature elongation.The multi-scale heterogeneous structure in the LPBF-fabricated GH4099 alloy enhances its microstructural thermal stability beyond that of conventional castings and forgings.Consequently,a high solution heat treatment temperature is necessary to achieve complete recrystallization.Following solution treatment at 1150℃ for 1.5 h,the columnar grains in the GH4099 prints were transformed into equiaxed grains,and large size twins were formed.Additionally,the precipitation of M_(23)C_(6) carbides at the grain boundaries was suppressed.During subsequent aging heat treatment,the recrystallization induced by the solution treatment mitigated the distortion energy stored in the 3D-printed grains,thereby suppressing γ'phase precipitation in the matrix.As a result,by optimizing the heat treatment process,a favorable balance between high-temperature strength and plasticity was achieved in the GH4099 alloy.

关 键 词：激光粉末床熔融 非平衡组织 热处理 γ'相 高温力学性能 

分 类 号：TG146[一般工业技术—材料科学与工程]