Shielding gas

About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.

Dissimilar Joining Between Austenitic and Duplex Stainless Steel in Double-Shielded GMAW: A Comparative Study

Abstract: In the present work, the effect of double-layer shielding and five other process parameters, namely welding voltage, current, primary shielding gas type, its flow rate, and filler material, is studied during dissimilar gas metal arc welding (GMAW) between austenitic and duplex stainless steels (SSs). A simple modification over the GMAW setup is made for additional supply of secondary shielding gas at different flow rates. Two different sets of welding are performed between austenitic and duplex SSs, i.e., AISI 304 with Duplex 2205 and AISI 316 with Duplex 2205, and the contributions of process parameters, their interactions on joint distortion, tensile strength, toughness, and fusion zone microhardness are evaluated. Improvements in joint quality due to the double-shielding environment are also highlighted. Double-layer shielding with secondary shielding by CO2 supply significantly improves tensile strength and toughness and reduces distortion. Fusion and interface zone microstructures are observed by sca...

Welding of gamma titanium aluminide alloys

Abstract: An article made of a gamma titanium aluminide alloy is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, cooling the entire article to a welding temperature of from about 1000° F. to about 1400° F., welding a preselected region in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected region so as to locally melt the alloy in the preselected region, providing a filler metal having the same composition as the gamma titanium aluminide alloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

Hot cracking behaviour of an autogenously laser welded Al-Cu-Li alloy

Abstract: AA2198 is a relatively new light-weight and high-performance Al-Cu-Li alloy considered for aviation and space applications. However, Al-Cu-Li alloys generally exhibit severe weldability problems for all fusion-welding techniques, such as laser-beam welding. In particular, porosity formation and hot cracking are observed for the laser-beam welding of these alloys. A common remedy for hot cracking is the use of an appropriate filler wire with a high Si content. In the present study, three different approaches for improving the hot cracking susceptibility of AA2198 laser beam welded without any filler material are presented. For this purpose, pre-heating of the weld samples to elevated temperatures, pre-loading of the weld samples perpendicular to the welding direction, or an optimization of the laser-beam welding parameters were conducted. The autogenously welded samples were assessed with regard to the resulting total crack length and their mechanical properties. It was demonstrated that all of the presented approaches led to a reduction of hot cracking. However, the largest effect was observed for the use of low levels of laser power and welding velocity. The mechanical properties of the optimised autogenously welded samples are only marginally inferior as for the samples laser welded with the Al-Si filler wire AA4047.

Analysis of weld characteristics of micro-plasma arc welding and tungsten inert gas welding of thin stainless steel (304L) sheet

Abstract: This research work focuses on comparison of the weld geometry, distortion, microstructure and mechanical properties of thin SS 304 L sheets (0.8 mm thickness) welded using micro-plasma arc welding ...