Functionally Graded Stainless Steel Fabricated by Direct Laser Deposition: Anisotropy of Mechanical Properties and Hardness
来源期刊：Acta Metallurgica Sinica2018年第1期
论文作者：Qiang Wang Song Zhang Chun-Hua Zhang Chen-Liang Wu Ling Ren Jian-Qiang Wang
文章页码：19 - 26
摘 要：Direct laser metal deposition is a kind of advanced rapid manufacturing technology, which can produce near net shape parts by depositing metal powders layer by layer. This study demonstrates fabrication, the anisotropy of mechanical properties and hardness of a graded steel. The characteristics of constituent phases, microstructure, mechanical anisotropy, and microhardness were investigated using electron backscatter diffraction, optical microscopy, tensile test machine, and microhardness tester. It was found that the graded steel is dense and free of cracks. The crystal structures of the as-built samples evolved in three grades from fcc structures to fcc+bcc structures and then to bcc+fcc structures. Samples in x and z directions showed obvious mechanical anisotropy. The samples machined in x direction showed higher strength and lower elongation than those machined in z direction due to the presence of lack-of-fusion pores and the higher metallurgical bonding between layers in the x direction. The microhardness of the as-built samples increased along the cross section from the substrate（159.7 HV） to the top surface（545.4 HV）.
Qiang Wang1,2,3，Song Zhang2，Chun-Hua Zhang2，Chen-Liang Wu2，Ling Ren4，Jian-Qiang Wang4
1. School of Stomatology, China Medical University2. School of Materials Science and Engineering, Shenyang University of Technology4. Institute of Metal Research, Chinese Academy of Sciences
摘 要：Direct laser metal deposition is a kind of advanced rapid manufacturing technology, which can produce near net shape parts by depositing metal powders layer by layer. This study demonstrates fabrication, the anisotropy of mechanical properties and hardness of a graded steel. The characteristics of constituent phases, microstructure, mechanical anisotropy, and microhardness were investigated using electron backscatter diffraction, optical microscopy, tensile test machine, and microhardness tester. It was found that the graded steel is dense and free of cracks. The crystal structures of the as-built samples evolved in three grades from fcc structures to fcc+bcc structures and then to bcc+fcc structures. Samples in x and z directions showed obvious mechanical anisotropy. The samples machined in x direction showed higher strength and lower elongation than those machined in z direction due to the presence of lack-of-fusion pores and the higher metallurgical bonding between layers in the x direction. The microhardness of the as-built samples increased along the cross section from the substrate（159.7 HV） to the top surface（545.4 HV）.
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