Luecke William E, Slotwinski John A
National Institute of Standards and Technology, Gaithersburg, MD 20899.
J Res Natl Inst Stand Technol. 2014 Oct 10;119:398-418. doi: 10.6028/jres.119.015. eCollection 2014.
Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands.
通过单轴拉伸和硬度测试，我们评估了采用增材制造工艺（选择性激光熔化）制造的奥氏体不锈钢UNS S17400的力学性能的变异性和各向异性。与锻造材料一样，力学性能取决于加工过程中引入的取向。推荐的消除应力热处理可提高抗拉强度、降低屈服强度并减小不连续屈服的程度。通过硬度评估的力学性能在整个成型板上非常均匀，但消除应力热处理引入了一个与成型板上位置无关的小不均匀性。对力学性能行为的分析得出了四个结论。（1）UNS S17400不锈钢在成型内部和不同成型之间的拉伸性能比成熟的工程结构合金更不可重复，但与通过增材制造制成的其他结构合金相似。（（2）本研究中UNS S17400材料力学性能的各向异性大于成熟结构合金，但与通过增材制造制成的其他结构合金相似。（3）通过选择性激光熔化制造的UNS S17400材料的拉伸力学性能与锻造、热处理的17-4PH不锈钢有很大不同。（4）所有测试中较大的不连续屈服应变是由吕德斯带的形成和扩展引起的。
