对316L不锈钢在激光快速成形过程中的凝固行为和组织形成进行了系统考察，发现，成形件呈现全奥氏体结构，其组织主要由从基体连续外延生长的细长列状枝晶组成，并显示较强的晶体取向性，其（100）晶向基本平行沉积方向，仅在顶部出现了一薄层转向枝晶层，而在成形件中出现的层带结构并未影响不同熔覆沉积层之间组织生长和取向的连续性，并采用最高界面生长温度判据对激光快速成形中的相形成规律进行了分析，并结合平界面稳定性分析，枝晶生长理论和我们所发展的列状晶／等轴晶转变模型对成形件中的层带形成，外延列状晶生长特性进行了较为系统的研究，并与实验结果得到了合理的吻合。
The solidification behavior and the morphological evolution of 316L stainless steel during laser rapid forming (LRF) were investigated. It was found that, there shows a complete austenitic structure in the LRF sample within the processing parameters of this study, there was continued epitaxial growth of the g phase of the fine columnar dendrites from the substrate, with the <100> crystallographic orientation leaning to, even parallel to the deposition direction. There also exist a thin layer in which the dendrites grow along the laser scaning direction at the top of the LRF sample. Clad layer bandings were found in the samples; however, the continuity of the growth of the columnar dendrites was not upset. The growth morphology of primary dendrites can be predicted by the microstructure selection models based on the maximum interface temperature criterion. The formation of the clad layer bandings and the epitaxial growth characteristic during LRF are also explained by the criteria for planar interface instability and dendritic growth theory and the columnar to equiaxed transition model. There shows an reasonable agreement between the theoretic analysis and the experimental results.
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