摘要
具有毛化凸点的金属零部件在工程中有广泛应用,精确控制毛化点形貌对实现精准控制相关零部件性能至关重要。以45钢为研究对象,采用二维轴对称模型仿真,探究脉冲激光作用下熔池内温度场、流体流向和流速的演变规律,据此研究毛化形貌形成的微观机理和动态过程。结果表明:在加热过程中,当表面温度低于临界温度时,切向应力为负,熔质流向熔池中心;当表面温度高于临界温度时,切向应力为正,熔质向边缘流动,最终在2个异向环流交界处形成对流零点;对于同种环流,切向应力越大,对应的流速峰值越大。超过临界温度后产生新环流,若环流流速较小,则削弱形貌变形量,若环流流速较大,则会在对流零点处产生异形形貌。
Metal parts with textured bumps are widely used in engineering, and controlling their morphology precisely is critical to control the performance of related parts accurately. In this paper, the 45 steel is taken as the research object, and a two-dimensional axisymmetric model is used to simulate to explore the evolution of the temperature field and the direction and velocity of fluid flow in the molten pool irradiated by the pulsed laser. Therefore, the microscopic mechanism and dynamic process of the formation of the textured morphology can be studied. The results show that during the heating period and while the temperature of the surface is below the critical temperature, the tangential stress is negative, and the melt flows to the center of the molten pool. If the surface temperature is above the critical temperature, the tangential stress is positive, and the melt flows to the edge of the molten pool, finally forming a convection-free location at the junction of the two circulations. For the same circulation, the greater the tangential stress is, the greater the peak velocity is. If the new circulation velocity is small when the surface temperature exceeds the critical temperature, it will weaken the deformation of the morphology at the last moment. Otherwise, an abnormal shape will be produced at the convection-free position.
作者
符永宏
黄婷
叶云霞
华希俊
李海波
钟行涛
Fu Yonghong;Huang Ting;Ye Yunxia;Hua Xijun;Li Haibo;Zhong Xingtao(School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2019年第7期92-100,共9页
Chinese Journal of Lasers
关键词
激光技术
激光微造型
切向应力
对流零点
表面流速
表面形貌
laser technique
laser texturing
tangential stress
convection-free location
surface velocity
surface morphology
