A thermo-metallurgical-mechanical model for selective laser melting of Ti6Al4V
A thermo-metallurgical-mechanical model for selective laser melting of Ti6Al4V
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DOI：
10.1016/j.matdes.2019.107642
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发表时间：
2019-04
影响因子：
8.4
通讯作者：
Pengfei Tan;Fei Shen;Biao Li;K. Zhou
中科院分区：
文献类型：
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作者：
Pengfei Tan;Fei Shen;Biao Li;K. Zhou
建立了一种热-冶金-力学耦合模型，用于预测Ti6Al4V多径多层选择性激光熔化过程的温度场、固相场和残余应力场。该模型考虑了固态相变（SSPT）和粉末-液-固相变，包括熔化、蒸发、凝固、收缩和冷却现象。热分析基于具有体积热源的瞬态热传导问题，描述了激光在粉末床中的吸收和散射。冶金相的体积分数演变由温度历史决定，并用于获得由SSPT引起的体积变化应变。提出了考虑热梯度和SSPT引起的应变的弹塑性本构法来评价应力场。模拟结果表明，考虑SSPT后，残余拉应力减小，残余压应力增大，且扫描方向残余应力分量大于其他两种应力分量。
A thermo-metallurgical-mechanical coupling model is developed to predict temperature, solid-state phase and residual stress fields for the multi-track multi-layer selective laser melting process of Ti6Al4V. The model considers the solid-state phase transformation (SSPT) and powder-liquid-solid transition which includes melting, vaporization, solidification, shrinkage and cooling phenomena. The thermal analysis is based on the transient heat conduction problem with a volumetric heat source describing the laser absorption and scattering in the powder bed. The volume fraction evolution of metallurgical phases is determined by temperature history and used to obtain the volumetric change strain due to the SSPT. An elasto-plastic constitutive law considering the strains that are induced by thermal gradients and the SSPT is proposed to evaluate stress fields. Modelling results reveal that the consideration of the SSPT leads to the decrease of tensile residual stresses and increase of compressive residual stresses, and the residual stress component in the scanning direction is larger than the other two stress components.