LPBF制备镍基高温合金组织演化及各向异性机制  

Microstructure evolution and anisotropy of nickel-based superalloy fabricated by LPBF

作　　者：李明川 马瑞[3] 常帅[1] 王奇舜 李俐群[1,2] LI Mingchuan;MA Rui;CHANG Shuai;WANG Qishun;LI Liqun(State Key Laboratory of Precision Welding and Joining of Materials and Structures,Harbin Institute of Technology,Harbin,150001,China;Zhengzhou Research Institute,Harbin Institute of Technology,Zhengzhou,450018,China;Beijing Power Machinery Institute,Beijing,100074,China)

机构地区：[1]哈尔滨工业大学,材料结构精密焊接与连接全国重点实验室,哈尔滨150001 [2]哈尔滨工业大学,郑州研究院,郑州450018 [3]北京动力机械研究所,北京100074

出　　处：《焊接学报》2025年第1期34-40,47,共8页Transactions of The China Welding Institution

摘　　要：通过改变激光粉末床熔融(laser powder bed fusion,LPBF)的扫描速度研究IN738LC合金组织演化及各向异性机制,采用光学显微镜(optical microscopy,OM)及扫描电镜(scanning electron microscopy,SEM)对组织形貌特征进行表征分析,通过X射线衍射(X-ray diffraction,XRD)对其织构性进行测试,使用显微硬度仪对显微硬度及各向异性进行评价.结果表明,随着扫描速度从800 mm/s提高到1600 mm/s,晶粒尺寸得到显著细化,且晶粒长轴取向由低扫描速度下沿建造方向择优,转变为高扫描速度下的沿熔池边界法线方向择优.这是因为低扫描速度下高熔池重熔率导致更多枝晶沿建造方向外延择优生长.这种沿建造方向的强择优生长同时导致(200)面沿建造方向择优的织构性,且这种织构强度随扫描速度增加而降低.这种(200)面沿建造方向择优织构还导致水平截面软轴居多,进而导致水平显微硬度低于侧界面显微硬度的各向异性.The microstructure evolution and anisotropy mechanism of IN738LC alloy under varying scanning speeds in laser powder bed fusion(LPBF)were investigated.Optical microscopy(OM)and scanning electron microscopy(SEM)were used to characterize the microstructural features,X-ray diffraction(XRD)was employed to examine the texture,and a microhardness tester was used to evaluate microhardness and anisotropy.The results showed that as the scanning speed increased from 800 mm/s to 1600 mm/s,the grain size became significantly smaller.At low scanning speeds,the grain major axis was preferentially aligned along the build direction.However,at high scanning speeds,the grain major axis transitioned to being aligned normal to the melt pool boundary.This was attributed to the higher melt pool remelting rate at low scanning speeds,which promoted more preferential epitaxial growth of dendrites along the build direction.This strong preferential growth along the build direction also resulted in a(200)texture along the build direction.The intensity of this texture decreased as the scanning speed increased.Furthermore,the(200)preferential alignment along the build direction led to an increased presence of soft axes in the horizontal section,resulting in anisotropy where the horizontal microhardness was lower than that of the side section.

关 键 词：扫描速度 激光粉末床熔融 镍基高温合金 微观组织 各向异性 

分 类 号：TG456.7[金属学及工艺—焊接] TH142.1[一般工业技术—材料科学与工程]