Causes of weld corrosion in austenitic steel containers employed in the milk industry

Abstract

This work was aimed at the explanation of the reasons for corrosion in a multilayer joint in a stainless steel milk container (1.4301). Metallographic examinations revealed the presence of strange areas with increased hardness in which a galvanic corrosion process had taken place. The chemical composition of the deposits (6.9 wt % of Cr and 3.4 wt % of Ni) was insufficient to achieve corrosion resistance. Incorrect chemical composition inside the weld deposit was caused by the usage of unsuitable filler material while running two internal layers. Reparation consisting of cutting off the improper beads (which had been made incompletely) was made, but following re-welding, the presence of corrosion-sensitive areas inside the weld was again found. The container was taken out of service after just 6 months use.