The effects of minor elements and shielding gases on the penetration of TIG welding in 304 stainless steel have been studied The bead-on-plate test was performed and then the depth and width of weld were measured using optical projection machine. On the other hand, the arc voltage was measured with an arc data monitor. In addition, the metallurgical characteristics of weld were examined using OM and SEM. The results show that oxygen and sulfur are beneficial in increasing depth /width ratio because of the increased surface tension temperature gardient. Element, such as aluminum, which has a deleterious effect on the depth I width ratio will combine with oxygen, and reduce the soluble oxygen content in the weld pool. On the other hand, silicon and phosphorus have minor effect on the depth /width ratio. Shielding gas using Ar + 1%O{sub}2 can significantly promote the depth/width ratio. The former is due to the increased the soluble oxygen content in the weld pool, and the latter is due to the production of hotter arc than pure argon.
Minor elements surface tension temperature gradient Weld pool Penetration Depth/width ratio