单晶镍基高温合金增材修复的定制化热处理-中国材料进展

文章信息/Info

Title:: Custom-Designed Heat Treatment for 3D-Printed Single-Crystal Ni-Based Superalloys

作者:: 林弈安; 王兆伟; 何卫锋; 罗思海; 陈凯; 1. 西安交通大学材料科学与工程学院，陕西西安 710049 2. 空军工程大学航空动力系统与等离子体技术全国重点实验室，陕西西安 710038

Author(s):: LIN Yian; WANG Zhaowei; HE Weifeng; LUO Sihai; CHEN Kai; 1. State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xi’an 710049, China 2. National Key Lab of Aerospace Power System and Plasma Technology, Air Force Engineering University,Xi’an 710038, China

Keywords:: single-crystal Ni-based superalloys; additive manufacturing; heat treatment; recovery; sub-solvus solutionizing

摘要:: 增材制造（3D打印）技术在镍基高温合金单晶叶片的修复领域展现出重要应用前景。该技术具有温度梯度大、冷却速度快等特点，有利于促进枝晶定向生长、实现枝晶组织细化，但是同时也容易产生高残余应力、高位错密度，从而在后续热处理与高温服役过程中引发再结晶、开裂等问题，造成极大的安全隐患。因此，需要对增材修复的镍基高温合金单晶开发定制化热处理研究。高温合金的标准热处理一般由超固相线固溶、时效等步骤组成。以增材修复高温合金单晶特有的微观组织为出发点，提出“筏化回复”及“亚固相线固溶”策略，有效抑制再结晶及3D打印产生的杂晶晶粒生长，同时有效降低位错密度、释放应力、调控沉淀强化相组织，为实现单晶涡轮叶片的增材修复提供保障。

Abstract:: Additive manufacturing (3D printing) is a promising route to repair damaged Ni0based superalloy single crystal blades. This technology is featured by steep temperature gradient and high cooling rate. The characteristics favor the directional growth of dendrites and realise microstructure refinement. However, additive manufacturing process also produce high residual stress and high microstructural defect density, which will trigger disastrous recrystallization and cracking in the subsequent heat treatment and/or high temperature service process. Therefore, customized heat treatment is demanded for the 3Dprinting repaired Ni0based superalloy single crystals. The standard heat treatment of superalloy generally consists of the steps of super0solvus solution and aging. Considering the unique microstructure of as0printed single crystal superalloys, the strategies of rafting0enabled recovery and sub0solvus solutionizing are demonstrated in this work, which effectively prevent recrystallization and stray grain growth, reduce dislocation density, release stress, and optimize γ′ morphology and volume fraction. Our study paves the way for the 3D0printing repair of damaged Ni0based superalloy single crystal turbine blades.