The TIG pulse welding parameters of 304L stainless steel sheet of 3 mm thickness in ¯at, vertical and overhead positions were investigated. The shielding gases were Ar, and ArN2 (0±5%, v/v). The base and pulse currents in all welding positions were adjusted to achieve a weld bead contour corresponding to DIN 8563 class AS at 3.4 mm/s welding speed, 1 pulse/s pulse frequency and 55% on-time. The weld bead aspect ratios (W/D) are 2.7±2.8. Increasing welding speed to 5 and 6.8 mm/s whilst simultaneously increasing the pulse frequency, the base and pulse currents, at constant 55% on-time was not successful in achieving weld bead contours to satisfy DIN 8563. In the vertical and overhead positions, gravitational force made the weld pool fall down, leading to undercut after solidi®cation. With the appropriate welding parameters, the gravitational effect can be eliminated. The d-ferrite content in the weld metals was in the acceptable range (3±12%, v/v) when the nitrogen content in the Ar shielding gas was between 3±5%, v/v. # 1999 Elsevier Science S.A. All rights reserved.