Shielding gas

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

Effect of oxygen content in He–O2 shielding gas on weld shape in ultra deep penetration TIG

Abstract: The effect of the shielding gas concentration on the weld shape was studied for the moving bead on plate TIG welding of SUS304 stainless steel under He–O2 mixed shielding. The small addition of oxygen to the helium base shielding gas can precisely control the oxygen content in a liquid pool and the weld shape. Oxygen is a surface active element for stainless steel. When the oxygen content in the liquid pool is above the critical value of ∼ 70 ppm, the weld shape suddenly changes from a wide shallow type to a deep narrow one due to the change in the Marangoni convection from the outward to inward direction on the liquid pool surface. Weld shape variations influenced by the welding parameters including welding speed, welding current and electrode tip work distance under pure He and He–0.4%O2 mixed gas shielding were systematically investigated. The investigation results showed that the final shape of the TIG weld depends to a large extent on the pattern and magnitude of the Marangoni convection on t...

Gas metal arc welding fume generation using pulsed current

Abstract: While the fume generation rate of gas metal arc welding (GMAW) is lower than some other arc welding processes, the further reduction of welding fumes is of interest to companies using GMAW. Several researchers have reported lower fume generation rates for pulsed welding current compared to steady current. However, the range of welding parameters where these reduced fume levels can be expected has not been well documented. This paper describes a study of the effects of pulsed welding current on the amount of welding fume and ozone produced during GMAW using a range of welding parameters. Fume generation rates were measured for steady current and pulsed current GMAW of mild steel using copper-coated ER70S-3 welding wire and 95%Ar-5% CO 2 and 85% Ar-15% CO 2 shielding gases. The amount of fume generated during welding was determined by drawing fume through a fiberglass filter using the standard procedures contained in ANSI/AWS F1.2. Results of these measurements show that pulsed welding current can reduce fume generation rates compared to steady current. There is a range of welding voltage that produces the minimum fume generation rate for each wire feed speed with both pulsed and steady current. The data also show that using pulsed current does not guarantee lower fume generation compared to steady current. Welding parameters must be correctly controlled if pulsed current is to be used to reduce fume levels. Fillet welds were made to demonstrate that the pulsed current welding parameters that reduce fume also produce acceptable welds. No significant difference was found in the chemical composition of fumes from pulsed current compared to steady current. Fumes generated by both types of current are mixtures of iron, manganese and silicon oxides. Measurements of ozone generation rates show that the pulsed current welding parameters that reduce fume also increase ozone generation compared to steady current welding

Gun and cable for gas metal arc welding

Abstract: An electrode gun and cable for feeding a welding electrode and shielding gas to a workpiece having an improved arrangement for supplying the gas to the arc and for electrifying the electrode in the contact tip. The cable is designed to resist abuse and purge air entering with the electrode. The gun nozzle has a square passage to receive the electrode guide and provide unobstructed gas passages. The trigger has a flexible member engaging the on-off switch to prevent damage thereto from too much pressure by the operator.