Effect of Heating Rate on Grain Refinement in Weld Metal of Type 430 Stainless Steel

- Grain Refinement in Weld Metal by Hot-wire GTAW Process -

Abstract

The aim of this study was to investigate the influence of power supply distance on the grain refining in weld metal of type 430 stainless steel. The fine grain formed conjunction with filler wire according to microstructure obtained by water quenching method. From the result, local melting occurred in filler wire before fine grain. The fine grains formed at the lower part of the weld metal when the wire current was low. On the other hands, the fine grain formed at the upper part when the wire current was high. The amount of the fine grain increased with increasing the wire current. Moreover, the area ratio of fine grain in weld metal increased with decreasing the power supply distance and the size of fine grain formed with each power supply distance in weld metal increased with increasing the power supply distance.
The effect of power supply distance on microstructure evolution in filler wire was investigated to obtain during heating of wire. Recrystallization and grain growth was observed in the heated wire. The grain size decreased with decreasing the power supply distance, because heating rate of wire increased with decreasing the power supply distance.