Repair welding of cracked turbine shroud using matching composition consumables

Abstract

Repair welding of a crack in the III-stage shroud of a high pressure turbine, was carried out using matching composition ER 410 filler wire by the gas tungsten arc welding (GTAW) process with ultra high purity argon as shielding and backing gas. The development of the repair welding procedure involved laboratory studies for the selection of a suitable ER410 filler wire, optimisation of welding parameters and PWHT. Mock up welding under simulated on-site constraints confirmed the feasibility to produce in situ sound weld joint. In situ repair welding and localised PWHT was carried out successfully. NDT and in situ metallography of the repair-welded region confirmed adequate tempering of the martensitic weldment during the localised PWHT.