TC4激光熔覆NiCrCoAlY热循环特性及组织性能

Research on thermal cycle characteristics and microstructure performance of TC4 laser cladding NiCrCoAlY

对TC4钛合金激光熔覆NiCrCoAlY涂层的热过程进行数值模拟仿真,探究工艺参数对热循环特性的影响规律,并进行激光熔覆试验验证.结果表明,当激光扫描速度相同时,激光功率越大,冷却速度越快,两者近似呈线性关系.当激光功率相同时,随着扫描速度的增大,冷却速度先增大后减小,出现拐点,随着激光功率的增加,冷却速度拐点对应的扫描速度减小.不同冷却速度得到的涂层组织和性能不同,冷却速度增加将细化晶粒提高涂层硬度,但过大将导致涂层产生缺陷.最佳工艺参数为激光功率600 W,扫描速度3 mm/s,适宜冷却速度为820℃/s.

Numerical simulation of thermal process of laser cladding NiCrCoAlY coating on TC4 titanium alloy is studied in order to explore the influence of process parameters on thermal cycle characteristics,and laser cladding experiments are tested and verified.The results show that when the laser scanning speed is the same,the greater the laser power,the faster the cooling speed,and they are approximately linear.When the laser power is the same,as the scanning speed increases,the cooling speed increases first and then decreases,and the inflection point appears.As the laser power increases,the cooling speed of the inflection point decreases which corresponding to the scanning speed.The microstructure and properties of the coating obtained by different cooling rate are different.The increase of cooling rate will refine the grains and improve the hardness of the coating,but the excessive cooling rate will lead to defects of the coating.The best process parameters are laser power 600 W,scanning speed 3 mm/s,and suitable cooling speed 820℃/s.