Laser cladding repair of turbine blades in power plants: from research to commercialisation

Abstract

Reliable and efficient power generation is a major global issue due to both political and environmental concerns. Nevertheless, many critical components, particularly the blades of the low pressure (LP) side of power generating steam turbines, are subject to failure due to severe erosion at the leading edges. Since taking machines offline for maintenance and removal of damaged blade for repair is extremely expensive, increasing the service life of these critical components offers significant economic and political benefits. Conventional techniques to increase service life include brazing of an erosion shield at the leading edge of the turbine blade, open arc hardfacing, and cladding with erosion resistant materials using gas tungsten, manual metal or plasma transferred arc welding. The authors have been investigating since 2001 the use of laser cladding technology to deposit a high quality and erosion resistant protection shield on the leading edge of LP blades. The project has demonstrated the feasibility of in situ repair of turbine blades in trials conducted at a power station using a fibre delivered diode laser and a robot. A company, Hardwear Pty Ltd, was established in late 2005 to commercialise this technology and has to date carried out successfully several commercial contracts involving the repair of 340 LP blades.