Data from: Subgrain-controlled grain growth in laser melted 316L promoting strength at high temperatures

Stainless steel 316L prepared by laser melting consisted of hierarchical austenitic microstructure with micron sized (10-25 µm) grains containing fine 1µm subgrains with a cellular structure. At high temperature thermal treatments (≥ 1100 °C), merging and growth of the 1 µm subgrains into bigger subgrains restricted the rapid grain growth and microstructure coarsening. Partial phase transformation of austenite to ferrite at temperatures ≥ 1100 °C in combination with gradual and steady growth of subgrains inside the micron sized grains and nucleation of sigma phase have promoted the tensile strength of stainless steel 316L to 300 MPa at 1100 °C compared to conventionally made 316L counterparts with tensile strength of approximately 40 MPa. The grain growth mechanism of laser melted microstructure can change the application criteria for 316L and expand the application fields for 316L.

通过激光熔融制备的316L不锈钢具有分层奥氏体微观组织，其内部包含10~25 μm的微米级晶粒，晶粒内存在具有胞状结构的1 μm细小亚晶粒。在≥1100℃的高温热处理过程中，1 μm亚晶粒发生合并与长大并形成更大尺寸的亚晶粒，从而抑制了晶粒的快速长大与微观组织粗化。当温度≥1100℃时，奥氏体向铁素体发生部分相变，结合微米级晶粒内部亚晶粒的缓慢稳定长大以及σ相的形核过程，使得该316L不锈钢在1100℃下的抗拉强度提升至300 MPa；而传统工艺制备的同规格316L不锈钢的抗拉强度仅约为40 MPa。激光熔融制备的316L不锈钢的晶粒长大机制，可改变该材料的应用判定准则，并拓展其应用领域。