Ti 함유된 스테인리스강 용접부의 전기화학적 특성

Abstract

Electrochemical characteristics of welded stainless steels containing Ti have been studied by using the electrochemical techniques in 0.5M H2SO4 + 0.01M KSCN solutions at 25oC. Stainless steels with 12mm thickness containing 0.2~0.9wt% Ti were fabricated with vacuum melting and following rolling process. The stainless steels were solutionized for 1hr at 1050oC and welded by MIG method. Samples were individually prepared with welded zone, heat affected zone, and matrix for intergranular corrosion and pitting test. Optical microscope, XRD and SEM are used for analysing microstructure, surface and corrosion morphology of the stainless steels. The welded zone of the stainless steel with lower Ti content have shown dendrite structure mixed with g and d phase. The Cr-carbides were precipitated at twin and grain boundary in heat affected zone of the steel and also the matrix had the typical solutionized structure. The result of electrochemical measurements showed that the corrosion potential of welded stainless steel were increased with higher Ti content. On the other hand, reactivation(Ir), passivation and active current(Ia) density were decreased with higher Ti content. In the case of lower Ti content, the corrosion attack of welded stainless steel was remarkably occurred along intergranular boundary and g/d phase boundary in heat affected zone.