Journal
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Volume 802, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2020.140431
Keywords
Selective laser melting (SLM); Ni-based composites; Tensile property; Creep property; Deformation mechanism
Categories
Funding
- Basic Strengthening Program of Science and Technology [2019-JCJQ-JJ-331]
- 5th Jiangsu Province 333 High Level Talents Training Project [BRA2019048]
- National Key Research and Development Program Additive Manufacturing and Laser Manufacturing [2016YFB1100101]
- National Natural Science Foundation of China for Creative Research Groups [51921003]
- 15th Batch of Six Talents Peaks Innovative Talents Team Program Laser Precise Additive Manufacturing of Structure-Performance Integrated Lightweight Alloy Components (Jiangsu Provincial Department of Human Resources and Social Security of China) [TD-GDZB-001]
- 2017 Excellent Scientific and Technological Innovation Teams of Universities in Jiangsu Laser Additive Manufacturing Technologies for Metallic Components (Jiangsu Provincial Department of Education of China)
- Funding for Outstanding Doctoral Dissertation in NUAA [BCXJ19-08]
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Submicron-WC reinforced Inconel 718 composites fabricated by selective laser melting exhibited a complex microstructure, with cellular and columnar dendrites forming within the molten pool. The optimal processing condition resulted in a highly dense composite with improved mechanical properties, while elongated grain boundaries caused reduced creep life and ductility. Deformation behaviors were related to microstructural defects, grain size, grain boundary morphology, and dislocation density.
In this study, submicron-WC reinforced Inconel 718 composites were fabricated by selective laser melting (SLM). They were investigated regarding forming quality, microstructure evolution, tensile and creep properties. The results demonstrated that SLM-processing with decreasing volumetric energy density (E-d), entailed the fabrication of composites with also decreasing density, due to the formation of more pores and cracks. The microstructure of the prepared composites mainly consisted of two different types, namely cellular and columnar dendrites, which formed within the molten pool. The microstructure was more heterogeneous at smaller length scale, whereby reduced grain size and enhanced high angle grain boundaries (HAGBs) were observed. At the optimal E-d of 120 J/mm(3), the SLM-fabricated composite was highly dense and exhibited small stress concentration, so that it showed the highest microhardness (361.7 HV0.2), ultimate tensile strength (1030.5 MPa) and elongation (24.8%). Owing to elongated grain boundaries, which were characteristic for the respective microstructure, the composite displayed reduced creep life and ductility. The deformation behaviors during tension and creep were analyzed and they were interrelated to the microstructural defects, grain size, grain boundary morphology, and dislocation density.
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