Wang Y Morris, Voisin Thomas, McKeown Joseph T, Ye Jianchao, Calta Nicholas P, Li Zan, Zeng Zhi, Zhang Yin, Chen Wen, Roehling Tien Tran, Ott Ryan T, Santala Melissa K, Depond Philip J, Matthews Manyalibo J, Hamza Alex V, Zhu Ting
Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Nat Mater. 2018 Jan;17(1):63-71. doi: 10.1038/nmat5021. Epub 2017 Oct 30.
Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.
许多传统的钢材强化方法通常是以牺牲有用的延展性为代价的，这一困境被称为强度-延展性权衡。新的冶金加工方法可能提供克服这一问题的可能性。在此，我们报告通过激光粉末床熔融技术增材制造的奥氏体316L不锈钢展现出屈服强度和拉伸延展性的组合，超过了传统316L钢。高强度归因于制造过程中形成的凝固致蜂窝状组织、低角度晶界和位错，而高均匀伸长率则与由层次化异质微观结构调节的稳定且渐进的加工硬化机制相关，其长度尺度跨越近六个数量级。此外，沿蜂窝壁和低角度晶界的溶质偏析可增强位错钉扎并促进孪生。这项工作展示了增材制造在制造具有独特微观结构和高性能的结构应用合金方面的潜力。
