PURPOSE: To enable welding with a weld zone excellent in quality and free from cracks by welding an Ni base sintered hard alloy heat resisting steel combining solution welding by arc welding method and specified heat treatment after welding.
CONSTITUTION: In manufacturing a turbine blade by welding using an Ni base sintered hard alloy heat resisting steel, the material to be welded is heated beforehand to 500W650°C, and TIG welding is performed while inserting a filler wire in inert atmosphere using Ar gas as shield gas. Minimum necessary welding current to melt the material to be welded is used and welding is performed in a short time. Before temperature of the weld zone drops to below 850°C (point A), the material is put in a heating furnace set at 850°C beforehand, heated to 1,100W1,200°C and kept for 1W5hr. Then, after slow cooling to room temperature (point B), the material is aged by heating to 820W860°C and keeping for 10W30hr. No cracking due to deposition of carbide occurs in the weld zone, and welding of Ni base sintered hard alloy heat resisting steel can be put to practical use.
TAKAHASHI KAZUYA
FUNAMOTO TAKAO
