选区激光熔化构建17-4PH钢残余奥氏体梯度分布  

Gradient distribution of residual austenite in 17-4PH steel constructed by selective laser melting

作　　者：王岩 田丰硕 谢信亮 韩李雄 魏瑛康 王建勇 张亮亮 贾文鹏 刘世锋[1] WANG Yan;TIAN Fengshuo;XIE Xinliang;HAN Lixiong;WEI Yingkang;WANG Jianyong;ZHANG Liangliang;JIA Wenpeng;LIU Shifeng(College of Metallurgical Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,Shaanxi,China;Key Laboratory for Light-weight Materials,Nanjing Tech University,Nanjing 211899,Jiangsu,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055 [2]南京工业大学轻质高性能材料研究中心,江苏南京211899

出　　处：《钢铁》2024年第5期134-144,184,共12页Iron and Steel

基　　金：国家自然科学基金资助项目(52104341);中国博士后科学基金资助项目(2021M702554,2022MD723810);陕西省自然科学基金资助项目(2022JM-259);陕西省科技厅攻关资助项目(2022GY-232)。

摘　　要：马氏体沉淀硬化(17-4PH)钢广泛应用于压缩机叶轮、水翼等具有复杂结构的过流部件。选区激光熔化(selective laser melting,SLM)作为一种新兴的近净成形技术,其逐点逐层的扫描堆叠制造方式有助于通过拓扑设计优化零部件结构和实现复杂形状零部件的一体成形。采用“交叉双向式”和“双向式”两种扫描策略交替打印17-4PH钢,探究选区激光熔化构筑17-4PH钢中的残余奥氏体梯度分布方法。研究结果表明,通过调控扫描策略,改变了热量输入和散失方式,可以在17-4PH钢中实现残余奥氏体含量梯度分布。交叉双向扫描策略可有效细化马氏体晶粒,马氏体晶粒的大小与构建高度相关,残余奥氏体晶粒的大小与扫描模式和构建高度关系不大。交叉双向扫描形成的细小马氏体会对周围奥氏体产生附加应力,提高残余奥氏体稳定性,导致试样底部奥氏体较多。双向扫描冷却速度快,过冷度较大,马氏体转变的驱动力增大,消除相稳定,造成顶部马氏体较多,残余奥氏体少。随着堆积层数的升高,组织的冷却速度由慢变快,马氏体的转变程度增加,残余奥氏体含量减少。实现了17-4PH钢中奥氏体梯度组织的控制,这种梯度组织的制备为优化材料性能和实现多功能应用提供了新的途径。Martensite precipitation hardening(17-4PH)steel is widely used in compressor impeller,hydrofoil and other over-flow parts with complex structures.Selective Laser Melting(SLM)is a new near-net-shape forming technology,and its point-by-point and layer-by-layer scanning stacking manufacturing method is helpful to optimize the structure of parts and realize the integrated forming of parts with complex shapes through topological design.The gradient distribution of retained austenite in 17-4PH steel constructed by selective laser melting was studied by alternately printing 17-4PH steel with two scanning strategies of"cross bidirectional"and"bidirectional".The results show that the gradient distribution of retained austenite content in 17-4PH steel can be realized by adjusting the scanning strategy and changing the heat input and dissipation mode.Cross-bidirectional scanning strategy can effectively refine martensite grains,and the size of martensite grains is related to construction height,while the size of retained austenite grains has little to do with scanning mode and construction height.The fine martensite formed by cross bidirectional scanning will produce additional stress on the surrounding austenite,which will lead to the stability of residual austenite and make the bottom of the sample more austenite.The cooling speed of bidirectional scanning is fast,the undercooling degree is high,the driving force of martensite transformation is increased,and the elimination phase is stable,resulting in more martensite at the top and less retained austenite.With the increase of stacking layers,the cooling rate of microstructure changes from slow to fast,the transformation degree of martensite increases and the content of retained austenite decreases.In this study,the control of austenite gradient structure in 17-4PH steel is realized,and the preparation of this gradient structure provides a new way for optimizing material properties and realizing multifunctional application.

关 键 词：选区激光熔化 17-4PH钢 奥氏体 马氏体 梯度组织 显微硬度 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TG665[金属学及工艺—金属材料]