How to effectively prevent porosity in TIG welding?

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Porosity often occurs during TIG welding; today we will introduce several causes of porosity and corresponding solutions. https://mmbiz.qpic.cn/mmbiz_png/YicY5UNbR1UoQEnbuu7GqFoU32zXonwrCqZb2apQjye8wHlW2oAS8unWd2Ra4JiaPkywyuFYCuACJ1dVsWTzYuLw/640?wx_fmt=png&wxfrom=5&wx_lazy=1&wx_co=1Causes of porosity: (1) Unclean base material ； The groove edges are not cleaned properly. (2) There are significant differences in composition and properties between the welding material used and the base metal. (3) Welding shielding gas issue. a) The argon pressure inside the gas cylinder is insufficient. b) The welding gas flow rate is adjusted too high. c) There is air leakage in the air supply pipe. d) The argon purity is insufficient, resulting in harmful gases mixing into the molten pool. e) The welding arc is too long, resulting in an insufficient effective distance for the shielding gas shield. f) The tungsten electrode extends too far, resulting in an insufficient effective distance for the shielding gas cover. g) The tungsten roll head or roll head sleeve is damaged by the arc, resulting in disruption of the protective gas flow. h) The air outlet of the welding torch is blocked by foreign objects, preventing smooth airflow and resulting in a reduced flow rate of the shielding gas. i) Inadequate wind protection measures, such as: drafts at the welding site that disrupt the protective airflow shield. (4) Welding operation issues. a) The welding torch angle is too large. b) During operation, when using an TIG welding torch with control buttons, gas was not released beforehand before welding, resulting in an excessively high gas flow rate at the moment of arc initiation. (5) Problems with the welding process. a) The welding speed is too fast. b) The arc extinguishing method is incorrect. c) The welding current is inappropriate. Preventive measures: (1) Clean the surface of the base material thoroughly; remove any residual oil, moisture, rust, etc. from the surface. The groove surface as well as the areas 10 mm on each side of the groove must also be polished clean. (2) Select the appropriate welding material. (3) Welding shielding gas issue. a) Check whether the bottle valve is fully open; if it is, it indicates that there is insufficient argon in the bottle, and the argon cartridge needs to be replaced. b) Regulate the flow rate of the protective gas again. c) Check whether there is any air leakage in the air supply pipe. d) The purity of argon should be no less than 99.7% when welding carbon steel, no less than 99.9% when welding aluminum, and as high as 99.99% for welding titanium and titanium alloys. e) Adjust the welding arc appropriately. f) Adjust the protrusion length of the tungsten electrode. g) Replace the tungsten roll head or roll head sleeve in a timely manner. h) Clean the welder torch air outlet promptly. i) Wind protection measures should be taken when the wind speed is >2 m/s. When welding pipes, the pipe ends must be sealed to prevent cross-wind from forming inside the pipes. (4) Welding operation issues. a) Adjust the angle of the welding torch. b) During operation, when using an TIG welding torch with control buttons, release air from it before welding. (5) Problems with the welding process. a) Adjust the welding speed appropriately. b) A method of extinguishing the arc that involves using a decaying current or adding welding wire to guide the arc toward the groove side and reduce its intensity; this prevents the arc from being extinguished suddenly, which could cause the hot molten pool to lose the effective protection provided by the argon gas flow, thus avoiding the formation of pores or shrinkages in the weld pool. c) Adjust the welding current to appropriate parameters. If the welding current is too low, the arc becomes unstable; the arc drifts unevenly at the tip of the tungsten electrode, disrupting the shielding zone. If the welding current is too high, the arc interferes with the airflow, resulting in a reduced shielding effect.