【摘要】 为研究激光熔覆涂层温度场的演变和残余应力的分布规律，在316L不锈钢基板上激光熔覆Inconel718 (IN718)合金，研究工艺参数对熔覆涂层宏观形貌的影响；基于实验所得工艺参数，利用Simufact Welding有限元软件建立热力耦合模型，通过数值模拟对熔覆过程中的温度场和应力场分布进行分析。结果表明：研究的工艺参数中，激光功率对涂层宽度的影响呈正相关性，送粉量对涂层高度呈较为明显的正相关性，而激光扫描速度对涂层高度呈较为明显的负相关性；熔池前端温度梯度最大，熔池尾部温度梯度较小；熔池峰值温度随着熔覆扫描的进行稳定于2 700℃左右；涂层最大残余应力为沿扫描方向上的拉应力，基板残余应力在涂层两侧呈对称分布，且最大残余应力为沿扫描方向的拉应力；残余拉应力是造成激光熔覆过程中基板“翘曲”变形的主要原因；基板与涂层热膨胀系数的差异是影响涂层与基板结合强度的另一原因。研究结果为后续基于实际工业中多层多道激光熔覆的研究奠定基础。更多还原

【Abstract】 To investigate the evolution of temperature field and the distribution law of residual stress of laser cladding coating, laser cladding inconel 718(IN718) alloy on 316 L stainless steel substrate was carried out to study the effect of process parameters on the morphology of the cladding coating.Based on the process parameters obtained from the experiments, the thermal mechanical coupling model was established by using the finite element software Simufact Welding, and the distribution of temperature field and stress field in the cladding process was analyzed.Results show that the laser power has a significant positive correlation with the coating width, and the powder feeding amount has a significant positive correlation with the coating height, while the laser scanning speed has a significant negative correlation with the coating height.The temperature gradient at the front of the molten pool is the largest, and the temperature gradient at the rear of the molten pool is small.The peak temperature of molten pool stabilizes at about 2 700 ℃ with the progress of cladding scanning.The maximum residual stress of the coating is the tensile stress along the scanning direction, the residual stress of the substrate is symmetrically distributed on both sides of the coating, and the maximum residual stress is the tensile stress along the scanning direction.The residual tensile stress is the main reason for the “warping” deformation of the substrate in the process of laser cladding.The difference of thermal expansion coefficient between substrate and coating is another reason that affects the bonding strength between coating and substrate.This research lays a foundation for the follow-up research based on multi-layer and multi-channel laser cladding in industrial application.更多还原