Abstract Welding system has now been concentrated on the development of new process to achieve cost savings, higher productivity and better quality in manufacturing industry. Discrete alternate supply of shielding gas is a new technology that alternately supplies the different kinds of shielding gases in weld zone. As the new developed methods compared to the previous general welding with a mixing supply of shielding gas, it cannot only increase the welding quality, but also reduce the energy by 20% and the emission rate of fume. As a result, under the same welding conditions, compared with the welding by supplying pure argon, argon + 67% helium mixture by conventional method and the welding by supplying alternately pure argon and pure helium by alternate method showed the increased welding speed. Also, the alternate method showed the same welding speed with argon + 67% helium mixture without largely deteriorating of weld penetration. The alternate method with argon and helium compared with the conventional methods of pure argon and argon + 67% helium mixture produced the lowest degree of welding distortion.