激光定向能量沉积DD6单晶高温合金的缺陷控制与晶体定向生长研究  

Research on Defect Control and Crystal Directional Growth of DD6 Single Crystal Superalloy Prepared Using Laser Directed Energy Deposition

作　　者：徐志旭 赵彦华 解伟放 韩秀平 李燕乐 田华 陈雷 谭滨 Xu Zhixu;Zhao Yanhua;Xie Weifang;Han Xiuping;Li Yanle;Tian Hua;Chen Lei;Tan Bin(School of Mechanical and Electronic Engineering,Shandong Jianzhu University,Jinan 250101,Shandong,China;School of Mechanical Engineering,Shandong University,Jinan 250061,Shandong,China;Logistics Management Office,Shandong Jianzhu University,Jinan250101,Shandong,China;School of Production-Education Integration,Shandong Jianzhu University,Jinan 250101,Shandong,China)

机构地区：[1]山东建筑大学机电工程学院,山东济南250101 [2]山东大学机械工程学院,山东济南250061 [3]山东建筑大学后勤管理处,山东济南250101 [4]山东建筑大学产教融合学院,山东济南250101

出　　处：《中国激光》2024年第20期199-212,共14页Chinese Journal of Lasers

基　　金：国家自然科学基金(51975339,51605262);山东省高校青年创新科技支持计划(2019KJB003)。

摘　　要：采用激光定向能量沉积技术,在不同工艺参数和沉积策略下对DD6单晶高温合金进行了熔覆沉积,探讨了缓解气孔、裂纹和杂散晶粒等缺陷与促进晶体定向生长的方法。结果表明:过低或过高的激光功率均不利于晶体的定向生长,同时会诱导未熔合、气孔、裂纹和杂散晶粒等缺陷的产生;当激光功率为1000 W、扫描速度为15 mm/s、送粉速率为10 g/min时,晶体定向生长比例可达到73.02%,在避免缺陷和保证晶体定向生长高度的同时,兼顾了增材效率;在优化的工艺参数下,采用间歇沉积策略,制得高度为4.6 mm的单道多层和多道多层单晶合金样品,晶体定向生长比例分别可达到83.73%和88.63%,揭示了工艺参数和沉积策略对微观缺陷和晶体定向生长的影响规律。Objective Laser directed energy deposition(L-DED)uses a laser as the energy source,which has higher temperature gradient and cooling rate,making it easier to alleviate metallurgical defects and promote the directional growth of crystals.However,during the preparation of multi-layer single crystal alloys,the heat input inside the molten pool is constantly changing,which increases the complexities of heat transfer and solidification in the molten pool.This is not conducive to the directional growth of crystals,and increases the risk of formations of stray grains and cracks.Therefore,this study reports the effects of the laser power,powder feeding rate,and scanning speed on the microstructure and defects of single-channel single-layer samples.The effects of single-channel multilayer and multi-channel multi-layer deposition strategies on the crystal growth and micro-defects are also presented.The results of this study can be used as a reference for the L-DED forming of single crystal components.Methods First,single-channel single-layer DD6 nickel-based single crystal superalloy samples are prepared using L-DED at different laser power values,and the microstructures of the samples are studied using optical microscope(OM).Then,samples are prepared using different laser power values,powder feeding rates,and scanning speeds in an orthogonal experiment.The microstructure of each sample is observed using OM,and the directional growth height of the crystals(H_(E)),molten pool depth(H_(R)),deposition height(H_(D)),and crystal directional growth ratio H_(E)/(H_(R)+H_(D))are measured.A range analysis is also performed.Then,the microstructures of single-channel multi-layer and multi-channel multi-layer samples prepared using a continuous deposition strategy are examined using OM and scanning electron microscope(SEM),and the precipitates are identified using energy dispersive spectrometer(EDS).Finally,the microstructures and grain orientations of single-channel multi-layer and multi-channel multi-layer samples prepared using an

关 键 词：激光定向能量沉积 DD6单晶高温合金 缺陷控制 晶体定向生长 

分 类 号：TG146[一般工业技术—材料科学与工程]