激光增材制造微观结构模拟与力学性能预测

Numerical simulation of microstructural evolutions and prediction of mechanical properties in laser additive manufacturing

提出一种考虑粒子数量的激光增材制造热源模型,模拟同轴送粉激光熔覆增材制造过程中的温度变化历史,通过与试验数据对比验证所提出新型热源的有效性。基于Monte Carlo方法发展一种新型多尺度计算模型以模拟双相钛合金增材制造过程中的相变和晶粒变化,采用有限元模型重构Monte Carlo模型所得到的微观结构模型,通过算例对比验证基于微观结构形貌的有限元模型对于双相钛合金力学性能预测的准确性,并进一步计算分析激光增材制造构件的流动应力。计算结果发现,采用考虑粒子数量的热源模型,可以更好地模拟增材制造热过程,增材过程中各层出现不同程度的重熔及重加热过程。微观结构计算结果表明,对增材制造过程微观结构的多尺度模拟是有效的,且可以较好地计算两相钛合金增材制造过程中的晶粒体分比变化及形貌。在对重构Monte Carlo模型计算所得微观结构进行力学性能测试中发现,计算所得流动应力均能较好地反映两相钛合金力学性能变化规律。

A new heat source model with consideration of the powder particles was proposed to simulate the temperature variations in laser melting deposition additive manufacturing.The comparison with experimental data shows the validity of the proposed model.Based on Monte Carlo method,a new multi-scale model was developed to simulate the phase transformation and grain growth in the additive manufacturing of the duplex titanium alloy.The obtained microstructure was reconstructed by finite element model.The predicted mechanical property was compared with experimental data for validations.Results indicate that newly proposed model with consideration of the powder particles is much more accurate for simulation of the remelting and reheating in laser melting deposition additive manufacturing.The results for microstructure show the validity of the proposed multi-scale model,and the volume fraction and grain morphology can be predicted with high accuracy.The reconstruction of the finite element model for the microstructure shows the mechanical property variation rules for duplex titanium alloy.