Abstract
The premature failure of parts designed to operate at high temperatures often occurs in low-ductility microstructures in a weld or its heat-affected zone (HAZ). Clearly, a knowledge of how the welding process variables determine these microstructures is essential to the designer of welding procedures. In an accompanying paper relationships are established which describe how the dimensions of single manual metal arc weld beads and their associated HAZs are related to the welding process parameters. Here it is shown how these relationships can be used to optimize the metallurgical properties of multipass welds by controlling the process parameters. The factors given particular attention are dilution of the weld metal by the parent material, refinement of the HAZ using controlled deposition, and refinement of the structure of the weld metal. Data for BOC Murex Suprex B welding electrodes and a mild steel substrate are used throughout for illustration, but the methods presented are applicable to other combinations of materials provided the correct material constants are used. The present work was prompted by a need to improve metal deposition rates during manual metal arc repair of foundry defects in large Cr–Mo–V castings. The practical implementation of the results is also considered.
MST/193b
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