Repair welding of cracked steam turbine blades using austenitic and martensitic stainless-steel consumables

The procedure for repair welding of cracked steam turbine blades made of ma rtensitic stainless steels has been developed using the gas tungsten are we lding process. Weld repair procedures were developed using both ER 316L aus tenitic and ER 410 martensitic stainless-steel filler wire. The overall dev elopment of the repair welding procedure included selection of welding cons umables (for austenitic filler metal), optimisation of post-weld heat treat ment parameters, selection of suitable method for local pre-heating and pos t-weld heat treatment (PWHT) of the blades, determination of mechanical pro perties of weldments in as-welded and PWHT conditions, and microstructural examination. After various trials using different procedures, the procedure of local PWHT (and preheating when using martensitic stainless-steel fille r wire) using electrical resistance heating on the top surface of the weldm ent and monitoring the temperature by placing a thermocouple at the bottom of the weld was found to give the most satisfactory results. These procedur es have been developed and/or applied for repair welding of cracked blades in steam turbines. (C) 2001 Elsevier Science B.V. All rights reserved.