Analysis of superalloy turbine blade tip cracking during service

High Pressure Turbine (HPT) first stage blade is the most important rotational components of aero-engine. It operates at high temperature and under conditions of extreme environmental attack such as oxidation and corrosion, is especially subjected to degradation by oxidation, corrosion and wear. During the service of aero-engine, the HPT first stage blades made of c 6 y nickel-based superalloy suffer from increasing blade tip cracks after hundreds of hours service. This significantly affects the whole engine function and, of course, safety of the aircraft. In this paper, the premature tip cracking of the HPT first stage blade is investigated. The research result shows that turbine blade tip is initially damaged by rubbing and corrosion over a period time, premature cracking of blade tip is caused by a combination mechanism of environment and thermal stress. During turbine blade maintenance and refurbishment, coating of both oxidation-resistance and abrasion-resistance should be applied in blade squealer tip to counteract the problem.