Influence of welding current intensity on pitting corrosion resistance in welded joint of stainless steel X5CrNi18-10

Abstract

The effect of welding current on the pitting corrosion resistance in the welded joint of austenitic stainless steel X5CrNi18-10 was tested. Welding was carried out using three different current intensity (110 A, 130 A and 150 A). Testing of pitting corrosion resistance was performed by electrochemical potentiodynamic method on the base metal, in the heat affected zone (HAZ) and in the weld metal. Values of pitting corrosion resistance indicators for the base metal are similar to values of the indicators for the weld metal, regardless of the applied welding current. The values of indicators for pitting corrosion resistance in the HAZ are less than the values of these indicators for the base metal and for the weld metal. This is caused by the precipitation of chromium carbides at grain boundaries and by partial formation of chromium depleted areas along the grain boundaries in the HAZ. HAZ that was formed at welding current of 150 A shows the smallest pitting corrosion resistance. This can be explained by the largest depletion in chromium of grain boundary areas at welding current of 150 A. The sensitization degree in the HAZ to intergranular corrosion is also the greatest, in this case. With increase of the sensitization degree to intergranular corrosion the value of metastable pitting potential linearly decreases, which means that pitting corrosion resistance in the HAZ is reduced.