Oxide Evolution During the Solidification of 316L Stainless Steel from Additive Manufacturing Powders with Different Oxygen Contents

Abstract

The oxide evolution during the solidification of 316L stainless steel from additive manufacturing powders with different oxygen contents is studied by in situ observation of the melting and solidification of the powder materials, advanced characterization of the solidified materials, and non-equilibrium thermodynamic analysis. An oxide evolution map is established for the 316L powders with different oxygen contents. It reveals the relationship between the surface oxidation in the reused powder and its expected oxide species and morphology in the as-solidified component. For the 316L powder with oxygen content higher than ~ 0.039 pct, the liquid oxide formed first from the steel melt and then crystallized to certain oxide phases during solidification, while for the powder with lower oxygen, oxide phases are suggested to directly form from the steel melt. The oxide species in the as-solidified sample was predicted by the Scheil–Gulliver cooling calculation and verified by the TEM-based phase identification. The oxides formed in the melt of low O 316L alloy (0.0355 pct O) are predicted to be (Mn, Cr)Cr2O4 spinel and SiO2 oxide. In the high O (0.4814 pct O) 316L melt solidification, the final oxides formed are (Mn, Cr)Cr2O4 spinel, SiO2 oxide, and Cr2O3 corundum. As an important characteristic of powder materials, the oxygen pick-up due to the powder surface oxidation significantly influences the inclusion evolution in the powder fusion process.

Effect of Various Heat Treatments on the Microstructure of 316L Austenitic Stainless Steel Coatings Obtained by Cold Spray

“…8 c) showed an enrichment in silicon, molybdenum, manganese, and oxygen. The presence of this type of silicate precipitates within the powder has already been reported in several studies in the case of laser powder bed fusion process (Ref 31 , 32 ).

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Combined effect of a spread powder particle size distribution, surface machining and stress-relief heat treatment on microstructure, tensile and fatigue properties of 316L steel manufactured by laser powder bed fusion

“…Moreover, the size of the manufactured samples (8 mm diameter for netshape series versus 20 mm for machined series) seems not to affect the porosity. When it comes to the effect of the heat treatment on porosity, considering both methods and their associated errors bars, no effect of this post-operational step is observed as already reported for such moderate temperature heat-treatments in literature [19,47,48]. As already reported in literature, both average value and statistical distribution of the powder particles can affect the surface roughness [27,32].…”

A Adoção De Soluções Computacionais No Processo De Manufatura Aditiva De Metais

“…AYDOGAN, (2022) Outro método bastante utilizado para simulações computacionais em WAAM é método de phase-field. O método de phase-field é utilizado para modelagem de transformação de fase e evolução microestrutural em sólidos (ZHU et al, 2002) pós de aço inoxidáveis 316L utilizado em AM (YANG et al, 2014). Pelo uso do MICRESS®, OKUGAWA et al (2022), ao estudar o refino de grão da liga hipoeutética alumínio-silício, viram que partículas cristalinas de Si permanecem próximas à linha de fusão mesmo após o rápido processo de refusão, servindo como sítios de nucleação heterogêneos no processo de resolidificação (OKUGAWA et al…”