基于有限元的激光增材过程熔化热积累模拟

Finite element simulation of melting heat accumulation in laser additive manufacturing

关键词:  H13模具钢  选区激光熔化  温度场  热积累

Key words:  H13 die steel  selective laser melting  temperature field  heat accumulation

摘要:

采用高斯体热源对H13模具钢的单层多道选区激光熔化温度场进行了模拟.研究了S型扫描时，不同扫描长度的热积累及其对熔池形貌的影响，通过试验验证了模拟结果的正确性，并提出了减小热积累的措施.结果表明，扫描长度越短，热积累越严重，熔池在第5道时的最高温度越高.以不同扫描长度的熔化长度、熔深和熔宽的平均增长率为标准可知，它们的平均增长率分别为32.1%，27.1%和13.5%.采用单向扫描的方式可减小热积累的程度，与S形扫描路径相比，当扫描长度为6 mm时，第5道的最高温度由3 115.6℃降低到2 881.51℃，但完成相同道次的扫描所用时间是S型扫描的两倍.

Abstract:

In this paper, the temperature field of single-layer and multi-beads Selective Laser Melting (SLM) of H13 die steel was simulated by using Gauss body heat source. The heat accumulation of different scanning lengths and its effect on the morphology of molten pool during S-type scanning were studied. The correctness of the simulation was verified by experiments and an improved measure was proposed to reduce the heat accumulation. The results show that the shorter the scanning length, the more serious of the heat accumulation, and accordingly the higher the maximum temperature of the molten pool in the fifth bead. By taking the average growth rates of melting length, melting depth and melting width under different scanning lengths as the standard, the average growth rates of them were 32.1%, 27.1% and 13.5%, respectively. The maximum temperature of the fifth bead was reduced from 3 115.6℃ to 2 881.51℃ when employed a unidirectional scanning at 6 mm. However, the time of completing the same pass is twice as much as that of the S-type scanning.