Abstract: A method of welding comprises forming an alternating current electric arc between an electrode (32) of a tungsten inert gas welding torch (30) and a metallic substrate (10). The alternating current has a square wave form which is self supporting and does not require intercycle high frequency support. The square wave alternating current has a wave bias ratio equal to or greater than 90% forward current to 10% reverse current. A metal welding rod (38) is supplied into the electric arc for depositing a weld deposit (40) on the metallic substrate (10). The welding method is used to apply a metallic wear resistant coating (40) to an edge surface (20 or 22) on a shroud (18) of a turbine blade (10) and is used to seal a cooling passage of a turbine blade or turbine vane.