300M钢激光熔覆耐磨防腐自润滑涂层温度场数值模拟研究

为了提高飞机起落架减震支柱300M超高强钢的抗磨性能,突破由于温度梯度过大诱发的激光熔覆耐磨防腐自润滑涂层裂纹等技术瓶颈,基于ANSYS软件的生死单元法编制热循环程序,考虑自润滑相和耐磨相材料热物性参数随温度的变化、相变潜热、激光熔覆过程中与外界的换热、激光熔覆功率、激光熔覆扫描速率等因素对激光熔覆过程温度场、熔池、温度梯度的影响,建立300M超高强钢激光熔覆耐磨防腐自润滑涂层温度仿真模型。结果表明:基体的熔化需要激光、熔化的粉末等综合作用使传导到该区域的有效能量达到熔化的临界值,熔化高度增加率随激光功率的增加先降低后增加,熔化高度减少率随激光扫描速率的增加先变小后变大;由于激光熔覆的不同区域温度、冷却速率差异等综合因素影响,熔覆层熔池的纵截面为勺状熔池;伴随激光功率的增加,由于熔覆层不同区域对能量输入产生的温度响应速率差异导致Z方向温度梯度值增加,且最大冷却速率增加;伴随激光扫描速率的增加,激光输入能量降低,降低了高温区域温度及激光的快速局部加热等综合影响,Z方向温度梯度值降低。通过调控激光参数,在保持熔覆层结合强度的条件下,基体熔凝区能被控制到最小,并能够降低温度梯度。

Numerical simulation of temperature field of wear-resistant anti-corrosion laser cladding self-lubricating coating on 300M super-strength steel

In order to improve the anti-wear properties of 300 M super-strength steel for aircraft landing gear shock absorbing strut,and to break through the technical bottleneck such as cracks induced by the excessive temperature gradient in laser cladding wearresistant anti-corrosion self-lubricating coating,the"birth and death"method and the APDL procedure of ANSYS were used to simulate the molten pool’s thermal cycle for the 300 M super-strength steel’s laser cladding wear-resistant anti-corrosion selflubricating coating.The change of thermophysical parameters with different temperatures for self-lubricant and wear-resistant materials,latent heat in phase change,external heat exchange during laser cladding,laser cladding power,laser cladding scanning velocity and other factors,which affect the temperature field,molten pool,temperature gradient during the laser cladding process were considered.The results indicate that the melting of the substrate requires a combination of laser and molten powder,etc.to bring the effective energy conducted to the region reach the critical value of melting,the increase rate of the melting height of the substrate decreases first and then increases with the increase of the laser power,the decrease rate of the melting height of the substrate decreases first and then becomes larger with the increase of the laser scanning speed.Due to the comprehensive factors of different temperatures and cooling rates in different laser cladding areas,the vertical section of the laser cladding wear-resistant anticorrosion self-lubricating coating bath is a spoon-shaped molten pool.With the increase of the laser power,due to the difference in the temperature response of the energy input to different regions of the cladding layer,the temperature gradient in the Z-direction and the maximum cooling rate increases.With the increase of laser scanning velocity,the laser input energy decreases,which decreases the combined effects of high-temperature region temperature and rapid local heating of the laser.Meanwhile,the temperature gradient in the Z-direction decreases.Under the condition of maintaining the bonding strength of the cladding layer,the substrate melting zone can be controlled to minimize and lower the temperature gradient by controlling laser parameters reasonably.