Selective corrosion of duplex stainless steel Part 2: Localized corrosion manifestations under exposure of chlorides on duplex stainless steel X2CrNiMoN22-5-3 and mechanical behavior in dependence of the microstructure

In completion to part 1 of this paper this part deals with interrelations b etween localized corrosion manifestations, mechanical properties and the mi crostructure of duplex stainless steel X2CrNiMoN22-5-3. The pit formation o n duplex stainless steels is substantially determined by the distribution o f the alloying elements within single phases and by defects in the oxide la yer. The positive properties of molybdenum become ineffective at thicker ox ide layers due to the fact, that molybdate, which is responsible for inhibi tion of pitting, can not be formed. Depletion areas caused by precipitation s are preferential attack places for corrosion. The influence of chlorides for duplex stainless steels in rolled and welded conditions is characterize d by a logarithmic dependence.