METHOD FOR REPAIRING CRACK

PROBLEM TO BE SOLVED: To repair a bucket, stationary blade, etc., in a gas turbine developing the crack caused by the driving for a fixed time to the almost original state with brazing by repeating a heating process for permeating brazing filler metal into the crack after heating to a prescribed temp. and a solidifying process for cooling and solidifying the molten brazing filler metal. SOLUTION: After setting the mixed brazing filler metal on the crack surface or filling this brazing filler metal into the crack, the heating at the temp. of the liquidus point or higher of this brazing filler metal, e.g. at the higher temp. by 10-30 deg.C than the m.p. thereof under vacuum condition, is executed. Under condition of melting the mixed brazing filler metal by heating gaseous argon is introduced into a furnace and the brazed part is rapidly cooled and solidified while returning back the pressure therein to the atmosphere. By these processes, void developed in molten mixed brazing filler metal is crushed to the small one or made to small to the large one and can be reduced. The void developed in the joining part can almost fully be removed by repeating these heating and cooling processes while combinating the void detection.