Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7974558 | Materials Science and Engineering: A | 2018 | 27 Pages |
Abstract
Si-bronze and 304 stainless steel were joined using gas tungsten arc (GTA) welding with two different welding (filler) rods matching the base metals. Cross-sections of the welds were analyzed using light optical microscopy (LOM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and hardness testing. Mechanical testing was performed for welds from each of the two filler metals using cross-weld tensile bars. For (1) the Si-bronze filler weld, partial mixing resulted in (a) copper-based regions with enhanced hardness due to iron-based islands and (b) iron-based regions with elevated hardness due to Si enrichment. Joint strength was ~ 90% that of the base Si-bronze strength of 340Â MPa, and elongation was ~ 48%, as compared to the base Si-bronze elongation of 55%. For (2) the stainless steel filler rod (a) primary austenite solidification and (b) micro-fissures were identified in the fusion zone. Thermodynamics calculation software was used to model solidification mode, demonstrating that the Cu (contributed by the Si-bronze) stabilized primary austenite solidification, which led to solidification micro-cracking or micro-fissuring. Micro-fissuring caused low ductility in the transverse weld tensile specimens. Fractography was performed to characterize the fracture mechanisms. For the stainless filler weld, a Cu film formed in interdendritic spaces between primary austenite grains.
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Physical Sciences and Engineering
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Authors
N. Switzner, H. Queiroz, J. Duerst, Z. Yu,