摘要
为了分析预置粉末Ni基合金熔覆过程的温度场和熔池的结晶变化规律,采用有限元方法建立了激光熔覆Ni基合金粉末过程的3维模型,考虑温度变化对热物理参量的影响以及表面对流换热和辐射散热等影响因素,使用SYSWELD软件对激光熔覆过程中的温度场和凝固结晶过程进行了分析及验证。结果表明,最高温度位于光斑中心处,等温线近似椭圆形,并且向外逐渐减小;熔覆层上某点热循环峰值温度随着热源的远离而明显降低,且热循环起始由第1道次的室温增大到最后道次的730℃;形状因子有结合界面处的1.9×109℃.s.mm-2降到熔覆层表面处的0.7×109℃.s.mm-2,同时,二次枝晶的间距在结合面处最大,表面处达到最小值,与相同工艺参量下的金相组织和凝固结晶理论完全吻合。该研究结果为激光熔覆过程的优化提供了指导意义。
In order to analyze the rules of temperature field and molten pool crystalline diversification during the preset powder Ni-based alloy cladding process,a 3-D model of laser cladding was made with finite element method.Taking consideration of the impact of temperature changes on the thermal physical parameters and the effects of heat convection and radiation heat,temperature field and solidification and crystallization of laser cladding process were analyzed and verified by SYSWELD software.The results show that the highest temperature is at the spot center,the isothermal line is almost elliptical and the temperature declines gradually along the radius of the spot center.Thermal cycle peak temperature at a certain point on the coating reduced significantly as the heat source was away.The temperature increased from the room temperature at the first pass to 730℃ at the final pass.Shape factor is reduced from 1.9×10^9℃ · s · mm^-2 of bonding surface to 0.7×10^9℃ · s · mm^-2 of cladding surface.At the same time,secondary dendrite spacing is the biggest at the bonding surface and the smallest at the cladding surface.The calculation results are perfectly matched with metallographic microstructure and solidification and crystallization theory.The results provide theoretical guidance for the optimization of laser cladding
出处
《激光技术》
CAS
CSCD
北大核心
2013年第4期547-550,共4页
Laser Technology
关键词
激光技术
NI基合金
有限元方法
温度场
凝固理论
laser technique
Ni-based alloy
finite element method
temperature field
solidification theory
