Study on the local corrosion behaviour and mechanism of bogie steel welded joints

The local corrosion behaviour and mechanism of welded joints were studied. The results show that the corrosion was caused by the distribution of microstructure defects in different areas of the weld. In the early stage, the potential difference between the base metal and the heat affected zone was less than 50 mV, so there would be no galvanic effect. As the corrosion progressed, the potential difference increased gradually, and the maximum value exceeded 160 mV. During this period, the corrosion rate was mainly affected by galvanic effect, and the order was weld seam > base metal > heat affected zone. • Defects on weld surfaces induce local corrosion. • Galvanic effects cause differences in the corrosion rates on both sides of the fusion line. • The galvanic series in different areas of the weld changes before and after corrosion.