Gas metal arc welding

About: Gas metal arc welding is a research topic. Over the lifetime, 11706 publications have been published within this topic receiving 109555 citations. The topic is also known as: metal active gas welding & GMAW.

Control of exposure to hexavalent chromium and ozone in gas metal arc welding of stainless steels by use of a secondary shield gas.

Abstract: Previous work has demonstrated that the shield gas composition in gas metal arc welding can have a considerable effect on hexavalent chromium [Cr(VI)] concentration in the fume and on ozone concentrations near the arc. Normally a single shield gas is used. This paper describes a double shroud torch that allows used of concentric shield gases of different compositions. A solid stainless steel wire was used for welding. The double shroud torch used secondary shield gases containing small amounts of the reducing agents NO and C 2 H 4 . The Cr(VI) concentration in the fume and ozone concentration at a fixed point relative to the arc were measured and compared with results when using a single shield gas. Use of the reducing agents in secondary shielding using the double shroud torch was found to offer advantages for ozone concentration reduction compared with use in a conventional torch, but this was not found to be an advantage for reducing Cr(VI) concentrations.

CO2 shielding gas effects in laser welding mild steel

Abstract: The most widely used shielding gases for laser welding of steels are helium and argon. Helium produces significantly more penetration than argon in penetration‐mode laser beam welding. Another gas that has been proposed as an alternative to these inert gases is carbon dioxide. The benefits of using carbon dioxide as a shielding gas for laser welding are that it costs less than helium and argon and that it provides nearly the same penetration as helium. The major drawback to its use as a shielding gas for mild steel is that it can cause porosity and other weld discontinuities. In this investigation helium and carbon dioxide were investigated as shielding gases in the laser welding of a fully killed 1018 steel, a semikilled 1018 steel, and an unkilled 1018 steel. Helium was generally found to produce discontinuity‐free welds, although small quantities of very fine centerline porosity were observed in the fully killed and semikilled steels. Carbon dioxide was found to provide an average of 70% of the penetration obtained with helium. The surface appearance and formation of porosity in welds made using carbon dioxide shielding was found to be dependent on the amount of deoxidizing element in the weld pool. While porosity‐free welds were formed in the semikilled steel (0.22% Si), low silicon or other deoxidizer content resulted in poor surface appearance and entrapped porosity in both the fully killed and unkilled steels in this investigation, presumably due to the formation of carbon monoxide in the weld pool. The addition of ferrosilicon powder to the weld pool effectively controlled the formation of carbon monoxide in these welds and resulted in porosity‐free welds with carbon dioxide shielding. The results of this investigation indicate that carbon dioxide can be used as a cost‐effective shielding gas for penetration‐mode welding of carbon steels. It was found that sufficient levels of deoxidizing elements must, however, be available in the molten pool to control porosity.

Semi-automatic hot wire tig welding equipment

Abstract: A semi-automatic hot wier TIG (Tungsten Inert Gas) welding equipment comprising: a portable TIG arc torch; a portable filler wire feed torch; a hot wire switching power source for energizing the TIG arc torch, the filler wire feed torch and a base metal; a filler wire feeding device for feeding the wire to the wire feeding torch at a desired rate; a welding condition control device for controlling wire heating power so as to provide wire heating power commensurate to the wire feed rate; means for measuring the resistance value of the wire extension section between the terminal end of the wire and the terminal end of the filler wire feed torch; and means for controlling said filler wire feeding means to change the wire feed rate in response to the detected wire extension According to the present invention, the welding operations are performed while the filler wire feed torch is held in one hand and the TIG arc torch is held in the other hand, so that the position where the arc and wire are inserted can be desireably adjusted Adjustment of the welding conditions such as regulation of the welding arc current and adjustment of wire feed rate can be readily performed during welding