QT600球墨铸铁激光熔覆数值模拟与实验研究  

Numerical Simulation and Experimental Research on the Laser Cladding Process of QT600 Nodular Iron

作　　者：许彦 李昌[1] 贾腾辉 陈馨雪 韩兴[1] XU Yan;LI Chang;JIA Teng-hui;CHEN Xin-xue;HAN Xing(School of Mechanical Engineering&Automation,University of Science and Technology Liaoning,Liaoning Anshan 114051,China)

机构地区：[1]辽宁科技大学机械工程与自动化学院,辽宁鞍山114051

出　　处：《表面技术》2022年第7期377-387,共11页Surface Technology

基　　金：辽宁省自然科学基金(2019ZD0277);辽宁科技大学创新团队建设项目(601009830);辽宁省高等学校创新人才支持计划(20201020)。

摘　　要：目的揭示QT600球墨铸铁激光熔覆动态演化过程的机理,为球墨铸铁熔覆过程中拓宽熔覆材料范围、优化工艺参数、改进熔覆质量提供理论依据。方法同时考虑移动高斯热源、材料物性参数温变影响、熔池表面张力和浮力对熔融态金属流动的Marangoni效应等因素,建立球墨铸铁激光熔覆多场耦合三维数值模型。通过QT600球墨铸铁激光熔覆实验,利用Zeiss−SIGMA HD场发射SEM观察熔覆层的形貌及显微组织,采用QNESS−Q10M硬度仪测试熔覆层和基体显微硬度。结果在光源中心形成了“椭球”状热影响区,沿激光扫描方向温度明显呈单峰分布,且周期性前移,流速在1 s时达到0.24 m/s,前半部熔池呈顺时针环流,后半部熔池呈逆时针环流,在活性元素影响下将导致熔池环流发生逆转。受温度梯度的影响,光斑后方呈收缩状应力带。数值模拟熔覆层形貌与实验一致,显微组织形态符合快速凝固原理的变化规律,验证了模型的有效性,熔覆层硬度明显高于基体,约为基体的1.6倍。结论数值模拟揭示了温度场、流场、塑性应力场瞬态演变规律,实验表明激光熔覆IN625合金粉末可有效改善球墨铸铁件的表面质量,提高其力学性能。Laser cladding is an emerging environment-friendly advanced manufacturing technology that effectively solves the defect repair and strengthening of the nodular iron castings,improving hardness and wear resistance,and prolonging service life.Due to the strong heterogeneity of nodular iron structure and chemical composition,complicated cladding process caused by the carbon diffusion of the graphite phase,and the limited selection of cladding powder.It is difficult to obtain the transient evolution law of multi-field coupling in the cladding process only by material science experiments.Therefore,in this paper,numerical modeling and experimental analysis are combined to study the transient evolution mechanism of IN625 laser cladding on QT600 nodular iron.Taking IN625 laser cladding on QT600 nodular iron as the research object,a 16 mm×30 mm×6 mm finite element model was established.The final mesh contains 140561 domain elements,7420 boundaries,and 300 edge elements.The number of freedom degrees that need to be solved is 784121(plus 156007 internal freedom degrees).The effects of moving Gaussian heat source,the temperature variation of material physical parameters,molten pool surface tension and buoyancy on the Marangoni flow of molten metal were considered.Based on the ALE dynamic mesh method,the liquid/gas interface movement of the molten pool was simulated.A temperature-flow velocity-stress full coupled numerical model of the cladding process was established.The calculation results show that an"ellipsoidal"heat-affected zone is formed in the cladding process with the center of the light source.The temperature along the laser scanning direction is in an obvious unimodal distribution which moves forward periodically.The flow velocity reaches 0.24 m/s at 1 s.The first half of the molten pool circulates clockwise,and the second half of the molten pool circulates anticlockwise.Under the influence of active elements,the circulation of the molten pool will be reversed.Affected by the temperature gradient,there is a shrin

关 键 词：激光熔覆 球墨铸铁 多场耦合 MARANGONI效应 

分 类 号：TG174.44[金属学及工艺—金属表面处理]