等轴晶
材料科学
极限抗拉强度
纳米压痕
分子动力学
粒度
晶界
冶金
层错能
复合材料
基质(水族馆)
沉积(地质)
图层(电子)
微观结构
化学
计算化学
海洋学
地质学
古生物学
生物
沉积物
作者
Kaiyuan Peng,Haihong Huang,Hongmeng Xu,Yu Sik Kong,Lingkai Zhu,Zhifeng Liu
标识
DOI:10.1016/j.ijmecsci.2022.108034
摘要
Understanding the microstructure evolution mechanism of certain alloys during the laser based directed energy deposition (L-DED) process is key to reaching the goal of adjusting the proceeding parameters and controlling the properties of deposited structures. However, it is significantly difficult to capture the corresponding microstructure changes explicitly. In this study, a large-scale molecular dynamics (MD) simulation model, consisting of a densely packed powder bed and a cracked substrate, is built to show the grain growth and crack repairing process of the stainless steel by L-DED. A continuous laser track is employed, while the localized heating and solidification of meltpools are emulated directly by controlling the temperature distribution inside the meltpool areas temporally. By investigating the forming mechanism of the deposited layer, the simulation results show that the epitaxial growth of the grain stems from the substrate region. The defects, such as vacancies, stacking faults, and twin boundaries are usually formed near the cracked sites due to the partial dislocation and the glide of the atom. It is also found that the number of equiaxed grains is significantly larger than the number of columnar grains in the deposited layer, which results in the fact that the average grain size by the L-DED deposition is closely associated with the equiaxed grain size. Furthermore, the MD model (nanoindentation tests, uniaxial tensile tests) also demonstrates qualitative consistency with the experiments. It is found that the enhanced hardness and ultimate strength surface are attributed to the grain refinement on the energy-deposited layer.
科研通智能强力驱动
Strongly Powered by AbleSci AI