標題: | Plastic anisotropy and deformation-induced phase transformation of additive manufactured stainless steel |
作者: | Chae, Hobyung Huang, E-Wen Jain, Jayant Wang, Huamiao Woo, Wanchuck Chen, Shi-Wei Harjo, Stefanus Kawasaki, Takuro Lee, Soo Yeol 材料科學與工程學系 Department of Materials Science and Engineering |
關鍵字: | Additive manufacturing;Stainless steel;Anisotropy;Phase transformation;Neutron diffraction |
公開日期: | 5-八月-2019 |
摘要: | Plastic anisotropy and deformation-induced phase transformation of additively manufactured (AM) stainless steels were investigated via in-situ neutron diffraction, electron backscatter diffraction, metallography, and fractography. Two types of tensile specimens were manufactured: (1) One sample was vertically fabricated with its tensile axis parallel to the z-direction (AM-V), (2) The other sample was horizontally fabricated with its tensile axis perpendicular to the z-direction (AM-H). A commercial 15-5PH stainless steel (CA) was used for comparison. AM steel revealed enhanced yield strength, tensile strength, and uniform elongation over CA, which was mainly due to grain refinement and transformation induced plasticity (TRIP). Different onsets of strain nonlinearity between AM-V and AM-H were closely related to martensitic phase transformation. Stresses estimated from lattice strains measured by neutron diffraction matched well with the applied stress-strain curves. After plastic deformation, voids were formed and congregated near the solidified line where fine grains were populated. Higher dislocation density was observed in the fine grain zone, and lower density was shown in the relatively coarse grain zone. AM steels exhibited significant anisotropic fracture behavior in terms of loading direction. In contrast to isotropic failure for CA and AM-V, AM-H revealed anisotropic failure with elliptical formation of the fracture feature. The fracture surface of AM-H possessed many secondary cracks propagating perpendicular to the building direction. The occurrence of secondary cracks in AM-H resulted in rapid load drop during tensile loading after necking. |
URI: | http://dx.doi.org/10.1016/j.msea.2019.138065 http://hdl.handle.net/11536/152578 |
ISSN: | 0921-5093 |
DOI: | 10.1016/j.msea.2019.138065 |
期刊: | MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING |
Volume: | 762 |
起始頁: | 0 |
結束頁: | 0 |
顯示於類別: | 期刊論文 |