Abstract:
Repair welding of C-Mn steel shaft forgings was carried out under simulated conditions of repairing, using different welding parameters and post weld heat treatment. The welding parameters were varied as preheat temperature, dia of electrodes and duration of post weld heat treatment at a given temperature of 510 °C. The repairing works were carried out as per ASME Section IX. Microstructure and mechanical properties of weld joints such as it's hardness, tensile strength and fatigue life were studied. It was observed that the use of low preheating and smaller dia of electrodes reduces grain coarsening of heat affected zone during post weld heat treatment due to promotion of martensite transformation in it. The increase in preheating temperature and size of electrode has been found to enhance the coarsening of grain size and pearlite colonies in the weld deposit during post weld heat treatment of the weld. During the use of higher size of electrodes weld joints were mostly found to fracture from base metal under tensile test of weld joints. During fatigue testing, the weld joints are always found to fracture from base material.
Thus the fatigue properties of the weld could not be identified. However it is marked that under the present conditions of welding used in this investigation, fatigue properties of weld are superior to those of base material.
