Shielding gas

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

Tig welding equipment and tig welding method

Abstract: The TIG welding methods of the present invention include generating an electric arc between an electrode and an object to weld the object, wherein a first shielding gas including an inert gas flows toward the welded object surrounding the electrode, a second shielding gas containing an oxidative gas flows toward the welded object along a periphery of the first shielding gas, and the concentration of the oxidative gas in the second shielding gas is set such that the oxygen concentration in the welded metal portion of the welded object is within a range of 70 to 220 wt. ppm.

Flux-cored wire for gas shielded arc welding for creep-resisting steels

Abstract: A flux-cored wire for gas shielded arc welding for creep-resisting steels, in which a flux is filled in a steel sheath and which is used in DC reverse polarity, comprises, based on a total weight of the wire, 1.0 to 5.0 mass % of BaF 2 , 0.3 to 3.0 mass % of Al, 0.04 to 0.15 mass % of C, 0.005 to 0.040 mass % of N, 1.0 to 2.7 mass % of Cr, 0.4 to 1.3 mass % of Mo, 0.05 to 0.5 mass % of Si, 0.5 to 1.5 mass % of Mn and 85 to 95 mass % of Fe, Ni being controlled to be at 0.1 mass % or below. This flux-cored wire used as a welding material for creep-resisting steels enables welding in all positions with good toughness and embrittlement characteristics.

Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding

Abstract: Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex microstructure without compromising the welding efficiency. 11.1 mm-thick standard duplex stainless steel plates were joined in a single-pass using this novel technique. Same plates were also subjected to conventional gas metal arc and plasma arc welding processes, providing benchmarks for the investigation of the weldability of the material. In the first place, the hybrid welding process enabled us to achieve less heat input compared to gas metal arc welding. Consequently, the precipitation of secondary phases, which are known to be detrimental to the toughness and corrosion resistance of duplex stainless steels, was significantly suppressed in both fusion and heat affected zones. Secondly, contrary to other keyhole techniques, proper cooling time and weld metal chemistry were achieved during the process, facilitating sufficient reconstructive transformation of austenite in the ferrite phase.

Method of laser beam welding galvanized steel sheets with an auxiliary gas containing oxygen

Abstract: Oxygen is mixed with another gas to form an auxiliary gas that will permit a welding of zinc-plated steel sheets (3a and 3b) without producing blowholes. An oxygen (O2) gas cylinder (4a) is provided in addition to an argon (Ar) gas cylinder (4b), for forming the mixed auxiliary gas, and the argon gas and the oxygen gas are mixed in a mixer (6) before being supplied to a machining head (7) and jetted onto a machining spot (9) through a nozzle (8). The oxygen oxidizes the zinc of the zinc-plated steel sheets (3a and 3b) to produce zinc oxide and zinc peroxide, to thereby prevent evaporation and minimize spatters, and thus permits a laser welding with a minimum generation of blowholes.