激光粉末床熔融修复定向DZ125合金数值模拟与实验研究  

Numerical simulation and experimental study of laser powder bed fusion for directional DZ125 alloy repair

作　　者：朱家瑞 戈昊宇 张玉衡 雍维 尹冰冰 贵云玮 付华栋[1,2] 束国刚 ZHU Jiarui;GE Haoyu;ZHANG Yuheng;YONG Wei;YIN Bingbing;GUI Yunwei;FU Huadong;SHU Guogang(School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China;Beijing Advanced Innovation Center for Materials Genome Engineering,University of Science and Technology Beijing,Beijing 100083,China;China United Gas Turbine Technology Co.,Ltd.,Beijing 100016,China)

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]北京科技大学北京材料基因工程高精尖创新中心,北京100083 [3]中国联合重型燃气轮机技术有限公司,北京100016

出　　处：《材料工程》2024年第12期15-28,共14页Journal of Materials Engineering

基　　金：国家科技重大专项项目(J2019-Ⅶ-0010-0150);国家自然科学基金项目(52301031);中国博士后科学基金项目(2024M750171)。

摘　　要：激光粉末床熔融(laser powder bed fusion,LPBF)技术具有成形柔性高、无需模具、快速制造等优点,特别适合于结构复杂、精密度高的航空发动机叶片修复工作,但仅通过实验方法难以高效准确地揭示多尺度多物理场耦合的LPBF过程中冶金缺陷和微观组织演变规律。利用有限体积法和元胞自动机模型分别模拟粉末床熔池形态演变与微观组织形成过程,结合实验观察,揭示不同打印参数下合金冶金缺陷和晶粒生长的演变规律。结果表明:LPBF修复过程中,能量密度显著影响熔池形貌,当能量密度小于87.9 J/mm^(3)时粉末颗粒熔化不完全,伴随有孔洞和熔合不良等缺陷形成,而当能量密度大于137.4 J/mm^(3)时,熔池凝固表面平整度明显降低。增加能量密度同时增强熔池水平方向热流干扰,晶体受到剪切力的影响进而导致与基体更大的取向差。此外,激光功率也显著影响着合金微观组织,随着激光功率的增加温度梯度逐渐减小,较低的温度梯度促进过冷液体区域形成,进而促进新晶核的形成,激光功率由150 W增加到250 W时,外延生长晶粒由柱状晶转变为大量杂晶。基于数值模拟方法分析获得LPBF修复DZ125合金的合理工艺参数为:P=200 W,V=1000 mm/s,H=65μm,该方法有助于降低实验成本,加速LPBF修复合金合理工艺参数的获取。Laser powder bed fusion(LPBF)technology offers significant advantages,including high flexibility,no mold requirements,and rapid manufacturing capabilities,so it is well-suited for repairing complex and precision components such as aero-engine blades.It is difficult to efficiently and accurately reveal the evolution rules of defects and microstructures in the multi-scale and multi-physical field coupling LPBF process through experimental methods only.The finite volume method and a cellular automaton model were used to simulate the morphological evolution of the powder bed melt pool and the corresponding microstructure formation process.Combined with experimental observations,the evolution rules of metallurgical defects in the alloy and grain growth under different printing parameters are revealed.The results indicate that during the LPBF repair process,energy density significantly affects the morphology of the melt pool.When the energy density is less than 87.9 J/mm³,the powder particles are not completely melted,accompanied by the formation of defects such as pores and unmelted areas.When the energy density is greater than 137.4 J/mm³,the surface smoothness of the solidified melt pool is significantly reduced.The increase in energy density enhances the horizontal thermal flow disturbance in the melt pool,and the crystals are affected by shear forces,leading to a greater orientation difference with the substrate.Additionally,the laser power significantly affects the microstructure of the alloy.As the laser power increases,the temperature gradient gradually decreases.The low temperature gradient promotes the formation of the supercooled liquid region,which in turn facilitates the formation of new crystal nuclei.When the laser power increases from 150 W to 250 W,the epitaxial growth grains change from columnar crystals to a large number of polycrystalline grains.Based on the numerical simulation methods,the optimal process parameters for repairing DZ125 alloy by LPBF are determined as follows:P=200 W,V=1000 mm/s,a

关 键 词：激光粉末床熔融 DZ125合金 有限体积法 元胞自动机 

分 类 号：TG132.3[一般工业技术—材料科学与工程] TB31[金属学及工艺—合金]