Ti6Al4V激光熔化沉积熔池温度场与微观组织特性  

Temperature Field of Molten Pool and Microstructure Property in Laser Melting Depositions of Ti6Al4V

作　　者：李俐群[1] 王建东[1] 吴潮潮 章敏[1] 赵维刚 

机构地区：[1]哈尔滨工业大学先进焊接与连接国家重点实验室,黑龙江哈尔滨150001 [2]上海航天设备制造总厂,上海200245

出　　处：《中国激光》2017年第3期113-120,共8页Chinese Journal of Lasers

基　　金：上海市重大技术装备研制专项(ZB-ZBYZ-01-14-1369)

摘　　要：采用激光熔化沉积方法制备了Ti6Al4V合金单墙体,研究了工艺参数对熔池尺寸稳定性、沉积层微观组织生长特性的影响。基于有限元模拟方法,计算了不同工艺条件下熔池的温度场及熔体的冷却速率。结果表明,在前几层的熔化沉积过程中,熔池尺寸会随基体散热条件的改变发生明显变化。对每层热量输入进行优化,可以准确控制熔池尺寸的稳定性。相比激光功率,扫描速度对沉积层定向生长特性及晶粒尺寸的影响更为显著,随着扫描速度的改变,沉积层组织很容易实现从柱状晶到等轴晶的改变。在本试验条件下,当熔池冷却速率高于135.3℃/s时,方可形成定向生长的柱状晶。Ti6Al4V alloy thin wall is prepared by using laser melting deposition, and the influences of process parameters on the size stability of molten pool and microstructure growth characteristics of deposited layers are studied. The temperature field of molten pool and cooling rate of melt under different process conditions are calculated based on finite element simulation method. The results show that the molten pool size varies significantly with the change of heat dissipation condition of substrate in the process of melting deposition of the first few layers. The heat input of each layer is optimized, which can realize the accurate control of stability of molten pool size. Compared with laser power, the influence of scanning speed on directional growth characteristic and grain size of deposited layer is more remarkable. With the change of scanning speed, the microstructure of deposited layer can easily transform from columnar crystal to equiaxial crystal. Under these experimental conditions, the directional growth columnar crystal can not be formed unless the cooling rate of molten pool is higher than 135.3 ℃/s.

关 键 词：激光技术 激光熔化沉积 钛合金 熔池稳定性 微观组织 冷却速率 

分 类 号：TN249[电子电信—物理电子学] TG113[金属学及工艺—物理冶金]