Oxygen Effects on Solidification Behavior of Gas Tungsten Arc–Welded Laser Powder Bed Fusion–Fabricated 304L Stainless Steel

Journal Article · Mon Apr 01 00:00:00 EDT 2019 · Materials Performance and Characterization

DOI:https://doi.org/10.1520/MPC20180115· OSTI ID:1530792

Gonzales, Devon Scott ^[1]; Liu, Stephen ^[1]; Javernick, Daniel Anthony ^[2]; Pacheco, Robin Montoya ^[2]; Brand, Michael J. ^[2]; Johnson, Matthew Q. ^[2]; Tung, David C. ^[2]

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1. Colorado School of Mines, Golden, CO (United States). Dept. of Chemistry and Geochemistry
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

ct The laser – powder bed fusion (L-PBF) process inherently accumulates interstitial gas elements during powder fabrication and laser deposition processes. Such elements can lead to localized variations in the weld pool and affect the solidification behavior (when compared with its wrought equivalent), in addition to chemical micro-segregation within the fabricated material. This study was conducted to characterize the solidification behavior of gas tungsten arc welds made on L-PBF 304L stainless steel. The effect of surface active elements on the local solidification rates was studied. An emphasis was placed on the role local solidification rates and temperature gradients throughout the weld play on the resultant weld solidification structure and micro-segregation. It was determined that gas tungsten arc welds on L-PBF 304L stainless steel exhibited a vermicular ferrite solidification structure compared to a mix of vermicular and lathy ferrite structure in wrought 304L. The varying thermal gradients affected the solidification modes and partitioning of elements leading to fluctuations of micro-segregation in the L-PBF 304L. Macroscopically, such partitioning affected the surface tension within the weld pool, producing asymmetric weld pool geometries. The compositional differences between wrought and L-PBF fabricated 304L stainless steels resulted in irregular solidification behaviors during welding affecting the final weld microstructure.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1530792
• Report Number(s): LA-UR--18-26056
• Journal Information: Materials Performance and Characterization, Journal Name: Materials Performance and Characterization Journal Issue: 4 Vol. 8; ISSN MPCACD; ISSN 2379-1365
• Publisher: ASTM International
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE