摘要
为了研究激光熔覆316L粉末多层堆积过程中熔覆层的Cr元素分布机制,建立了一种基于体积平均法的三相熔化凝固模型,模拟多层激光熔覆过程中的熔池流动、传热和传质现象。对模拟结果与实验结果进行比较分析,验证了模型的可靠性。通过分析激光熔覆多层316L粉末过程中的温度场、流场以及元素分布的瞬态变化,以Cr元素作为粉末的示踪元素获得了熔覆层的元素分布机制。结果表明:由于Marangoni效应,熔池内形成了位于熔池前端的顺时针方向涡流和后端的逆时针涡流,熔池最大流速出现在熔池后端表面;在前三层熔覆过程中,随着层数增加,熔池表面温度梯度下降导致熔池最大流速减小,而在热积累作用下熔池体积明显增大,但熔池内部流态不发生改变。同时,第二、三层熔覆时熔覆层发生部分重熔,重熔区内的基体元素在熔池内被粉末元素再次稀释,导致粉末元素的含量在熔覆层内逐层上升,最终获得从基体元素向粉末元素过渡的熔覆层。
Objective In the laser cladding process,a multi-cladding layer with a large thickness is required to satisfy the requirements of industrial production.To improve the performance of the cladding layer,the powder metal is different from the matrix,and therefore,the elements in the cladding layer need to change from matrix to powder elemental composition.The properties of the cladding layer are affected by the distributions of elements.The faster the cladding elements change from matrix elements to powder elements,the more metal powder elements are contained in the cladding layer,which has better abrasion resistance.Therefore,it is of great significance to analyze the transient changes in the temperature field,flow field,and element distribution by numerical simulation of the laser cladding 316L powder multilayer stacking process as well as study the distribution mechanism of Cr elements in the cladding layer,providing a theoretical basis for the cladding layer to contain a higher proportion of powder elements and fewer matrix elements.Methods The multilayer laser cladding process of 316L powder on a 45-steel matrix is studied using a three-phase melting and solidification model based on the volume averaging method.The distribution mechanism of elements in the process of cladding layer stacking is clarified by comparing and analyzing the changes of temperature field,flow field,and solute field in the first three layers.The simulation results are verified from four aspects:the geometric morphologies and Cr concentrations of the first and second cladding layers.Results and Discussions The geometric morphologies of the molten pool and element distributions of the cladding layers are verified by comparing the experimental and simulation results of the first and second cladding layers in the stacking process(Figs.4,5,and 6).The Cr element is used as a tracer element to analyze the distribution mechanism of the cladding layer element(Fig.10).The simulation results show that the molten pool morphologies and Cr element dist
作者
金宸宇
葛鸿浩
张亚周
董刚
张群莉
李琳
姚建华
Jin Chenyu;Ge Honghao;Zhang Yazhou;Dong Gang;Zhang Qunli;Li Lin;Yao Jianhua(Institute of Laser Advanced Manufacturing,Zhejiang University of Technology,Hangzhou 310014,Zhejiang,China;College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310014,Zhejiang,China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment,Hangzhou 310014,Zhejiang,China;Laser Processing Research Centre,The University of Manchester,Manchester M139PL,Britain)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2023年第12期121-133,共13页
Chinese Journal of Lasers
基金
国家自然科学基金重点项目(52035014)
浙江省“领雁”研发攻关计划(2022C01117)
浙江省公益技术应用研究项目(LGG20E050019)。
关键词
激光技术
多层激光熔覆
元素分布
数值模拟
laser technique
multilayer laser cladding
element distribution
numerical simulation
