摘要
目的突破气门座激光熔凝收尾凹坑缺陷技术瓶颈。方法建立激光熔凝强化RuT300的三维瞬态温度场仿真模型,模型中考虑激光吸收率、材料相变潜热及热物性参数的影响,并结合Niyama判据,分析激光熔凝强化RuT300收尾过程激光参数线性变化对收尾凹坑缺陷的影响规律。结果在激光熔凝收尾过程中,对比未采用激光参数线性变化的收尾方式,采用激光功率线性下降(斜率为–400)的参数变化方式时,G/√D的最大值由最初的0.0085增大至0.0097;当斜率由–100减小至–400时,G/√D的最大值由最初的0.0087增大至0.0097;采用激光扫描速度线性上升(斜率为20)的参数变化方式时,G/√D的最大值由最初的0.0087增大至0.0142;当斜率由5增加至20时,G/√D的最大值由最初的0.0112增大至0.0142。伴随着激光功率线性下降或激光扫描速度线性上升,激光熔凝气门座收尾凹坑有缩减趋势,且伴随着激光功率线性下降过程斜率绝对值或激光扫描速度线性上升过程斜率的增大,收尾凹坑有进一步缩减趋势。实验分析与数值模拟结果基本吻合,说明了模型的有效性。结论在激光熔凝收尾过程中,采用激光功率线性下降或者激光扫描速度线性上升方法可以抑制收尾的凹坑缺陷,提升气门座的可靠性。
The work aims to break through the technical bottleneck of the laser melting ending pit defect on valve seat.A laser melting strengthening RuT300 three-dimensional transient temperature field simulation model was established and the influence of laser absorption,material phase change latent heat and parameters in thermal and physical properties were considered.Combining with Niyama criterion,the influence of laser parameter linear change on end pit defects was analyzed during end process of strengthening RuT300 by laser melting.In the process of laser melting ending,compared with the ending method without linear change of laser parameters,when the laser power was linearly decreased(the slope was–400),the maximum value of G/√D increased from the initial 0.0085 to 0.0097.When the slope decreased from–100 to–400,the maximum value of G/√D increased from the initial 0.0087 to 0.0097.When the laser scanning speed increased linearly(the slope was 20),the maximum value of G/√D increased from the initial 0.0087 to 0.0142.When the slope increased to 20 from 5,the maximum value of G/√D increases from the initial 0.0112 to 0.0142.With the linear decrease of laser power or the linear increase of laser scanning speed,the ending pit of laser melting valve seat had a decreasing trend,and with the increase of the absolute value of the slope in the linear decline of laser power or the increase of the slope in the linear rise of laser scanning speed,the ending pit had a decreasing trend.The results of experiment analysis and numerical simulation were basically consistent,which showed the validity of the model.In the process of laser melting ending,linear reduction of laser power or linear rise of laser scanning speed can be used to suppress the pitting defects at the end and improve the reliability of valve seat.
作者
庞铭
张啸寒
PANG Ming;ZHANG Xiao-han(School of Airport,Civil Aviation University of China,Tianjin 300300,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2019年第10期131-138,共8页
Surface Technology
基金
国家自然科学基金(U1633111,51206179)
中央高校基本科研业务费项目中国民航大学专项资助(3122018D020)
中国民航大学蓝天青年科研资金资助项目~~
关键词
激光熔凝
凹坑缺陷
数值模拟
Niyama判据
蠕墨铸铁
温度场
laser melting
pit defect
numerical simulation
Niyama criterion
vermicular graphite cast iron
temperature field
