Repair brazing of gas turbine hot parts: Methods and joint characterisation

This paper describes the use of repair brazing for gas turbine hot parts, especially vanes and blades. The limited weldability of superalloys that can operate at high temperatures and under high mechanical loading, required in modern gas turbines, has lead to the development of repair brazing techniques for various crack types and for restoration of dimensional changes. Methods to characterise these joints are necessary for the development work, the quality control of the procedures and acceptance of refurbished parts. These methods are mainly various NDT techniques, metallography and service simulating mechanical testing, such as creep and thermal fatigue testing of joints.