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Evolution of the Structure and Properties of High-Chromium Heat-Resistant VZh159 Alloy Prepared by Selective Laser Melting: Part II
摘要： The evolution of the structural-phase state of the VZh159 alloy fabricated by selective laser melting after various types of thermal exposure and hot isostatic pressing (HIP) is studied. The effect of a long 500-h exposure at temperatures of 800 and 900°C on the phase composition and morphology of structural components is determined. The short-term and long-term strength of the material in various conditions are studied. It is shown that the segregation of dispersed particles of the σ phase after the gas-static treatment followed by aging and after prolonged exposure at high temperatures does not have a significant negative effect on the plastic and strength characteristics of the alloy. The long-term strength of the synthesized metal after the 500-h exposure at a temperature of 900°C corresponds to the certified values for the deformed semifinished product of the VZh159 alloy.
关键词： boride,heat treatment,σ-phase,HIP,gas-static treatment,VZh159,selective laser melting (SLM),transmission electron microscopy,cellular structure
更新于2025-09-19 17:13:59
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Evolution of the Structure and Properties of High-Chromium Heat-Resistant VZh159 Alloy Prepared by Selective Laser Melting: Part I
摘要： The evolution of the structural-phase state of the VZh159 alloy fabricated by selective laser melting after various types of thermal exposure and hot isostatic pressing (HIP) is studied. The effect of a long 500-h exposure at temperatures of 800 and 900°C on the phase composition and morphology of structural components is determined. The short-term and long-term strength of the material in various conditions are studied. It is shown that the segregation of dispersed particles of the σ phase after the gas-static treatment followed by aging and after prolonged exposure at high temperatures does not have a significant negative effect on the plastic and strength characteristics of the alloy. The long-term strength of the synthesized metal after the 500-h exposure at a temperature of 900°C corresponds to the certified values for the deformed semifinished product of the VZh159 alloy.
关键词： σ phase,VZh159,HIP,heat treatment,boride,transmission electron microscopy,gas-static treatment,selective laser melting (SLM),cellular structure
更新于2025-09-19 17:13:59
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An investigation into the effect of gradients on the manufacturing fidelity of triply periodic minimal surface structures with graded density fabricated by selective laser melting
摘要： Triply periodic minimal surfaces (TPMSs) have attracted increasing attention for their high manufacturability, biocompatibility, and mechanical properties. In this work, graded Gyroid cellular structures (GCSs) with varying gradient directions were mathematically designed and manufactured via selective laser melting (SLM). The effect of gradients on manufacturing fidelity, i.e. degree of conformity between the manufactured part and engineering design, of these structures was investigated using X-ray computed tomography (CT). The results indicate that relative density and volume fraction of as-built GCSs are higher than those specified in the engineering design due to strut diameters being larger than specification and the presence of bonded powder particles. Manufacturing fidelity is shown to depend on the geometry of the struts in these structures, including inclination angle of struts, relative density, and density gradient direction. Bonded powder particles were particularly present at the upper inner walls of sphere-like pores, where inclination angles are low and as a result there is a lack of support and non-ideal transfer of heat from the melt pool. Decreasing density along the building direction reduces the occurrence of bonded powder particles and increases manufacturing fidelity. The empirical findings in this study provide insight into the effects of part geometry on the quality of its manufacture by SLM. Results are used to establish guidelines for optimal design of cellular structures.
关键词： Graded cellular structure,Gyroid,Selective laser melting,Triply periodic minimal surface,X-ray computed tomography
更新于2025-09-12 10:27:22
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The passivity of selective laser melted 316L stainless steel
摘要： The passive film properties of as-received selective laser-melted 316L stainless steel (SLMed 316L SS) without obvious pores were studied and compared with those of wrought and solution-annealed (SA) SLMed 316L SSs. Among the samples, the as-received SLMed 316L SS had the lowest passive current density, which was attributed to two factors: the super high sub-grain boundary density increased the number of nucleation sites for passive film formation, and the micro-galvanic effect between the sub-grain boundary and the inner sub-grains also accelerated the rapid formation of a thick protective layer. The poor passivation and re-passivation abilities of the SA SLMed 316L SS were ascribed to the extensively precipitated nanosized oxide and sulfide particles, especially those at the grain boundary.
关键词： Cellular structure,Passive film,Stainless steel,Selective laser melting,AFM
更新于2025-09-12 10:27:22