摘要
设计了一种L型基体去模拟气门座激光增材带侧壁的约束结构,构建带约束结构的激光增材仿真模型,并考虑了激光吸收率的变化、材料相变潜热、增材过程与外界的换热等因素的影响。结果表明:激光的空间能量密度变化和激光的空间能量输入存在竞争关系,当提高激光功率、增加功率密度对温升的效果大于增加速度、降低空间能量对温度下降的效果时,增材层温度增大;由于基体结构的非对称性及激光增材过程中传散热的综合影响,增材层与基体底面熔合的深度会大于其与侧面熔合的深度,且增材层横截面形貌为台阶式月牙形;由于热传导的滞后性及激光的快速加热和冷却等的综合作用,随着激光功率和扫描速度的增加,增材层底面形貌由月牙形逐渐过渡到平台形。
In this study,an L-shaped model was designed to simulate the constraining structure of the laser additive strip sidewall of a valve seat to construct the constrained structure. The basic laser additive simulation model considers the changes in laser absorptivity,latent heat of phase change of the material,and heat exchange between the additive process and the external environment. Results show the existence of a competitive relationship between the laser energy density change and the energy input of the laser in space. When the effect of increasing the laser power and power density on the temperature rise is greater than the effect of increasing the speed and reducing the energy in the space on the temperature drop,the temperature of the additive layer increases. Because of the influence of the substrate structure asymmetry and the heat transfer and dissipation in the laser additive process,the depth of fusion between the additive layer and the bottom surface of the substrate is greater than the depth of fusion with the side surface and the cross section of the additive layer has a stepped-crescent shape. Furthermore,because of the combined effects of the hysteresis of heat conduction and rapid heating and cooling of the laser,with the increase in laser power and scanning speed,the cross-sectional profile of the additive layer gradually switches from a crescent to a platform shape.
作者
郎甜甜
庞铭
Lang Tiantian;Pang Ming(Airport College,Civil Aviation University of China,Tianjin 300300,China)
出处
《激光与光电子学进展》
CSCD
北大核心
2021年第11期271-279,共9页
Laser & Optoelectronics Progress
基金
中央高校基本科研业务费项目中国民航大学专项(3122018D020)
中国民航大学蓝天青年科研资金资助项目。
关键词
激光光学
激光熔覆
球墨铸铁
气门座
熔池
laser optics
laser cladding
ductile iron
valve seat
molten pool
