Structure and properties of soldered joints of the high-alloyed nickel alloys obtained by arc heating in the vacuum

Abstract

Repair of blades made of the cast high-temperature nickel alloys with the volume content of γ’-phase of 50...65% and more by fusion and built-up welding practically leads to no results. Only introduction of special methods in certain cases provides restoration of a section satisfying the blade operation conditions. Therefore, the leading foreign and domestic enterprises mainly use high-temperature soldering in vacuum with general heating to repair blades of the nozzle unit, flaps of the adjustable nozzle and other parts of the gas turbine hot pass. It becomes possible to increase performance of the permanent joints (especially the small ones) by high-temperature soldering with the lowest acceptable thermal effect on the base metal through local heating in vacuum by the arc discharge with the hollow cathode. Arc soldering in vacuum with supply of the powder composite solders to the greatest extent combines advantages of built-up welding and high-temperature soldering with the general heating. Results of metallographic studies and mechanical tests of the solder joints obtained by arc soldering in vacuum with powder composite solders on samples with imitation of the surface defects showed higher performance compared to that for joints created by high-temperature soldering in vacuum with general heating.