Efeito do tratamento térmico de solubilização sobre a corrosão por pite de em aço inoxidável austenítico contendo alto de Mn em solução de cloreto

The effect of solution heat treatment on the pitting corrosion resistance of\ud 17Cr-6Mn-5Ni-1.5Cu austenitic stainless steel in 0.6M NaCl aqueous solution was\ud evaluated. UNS S30403 (304L) steel was used as benchmark material. Solution heat\ud treatments (SHT) were conducted at 1010°C, 1040°C, 1070°C and 1100°C. The microstructural\ud characterization revealed the presence of δ-ferrite, especially in the asreceived\ud condition (AR). The SHT decreased the proportion of the ferrite phase. Mnrich\ud precipitates were observed in the as-received condition of 17Cr-6Mn-5Ni-1.5Cu\ud steel, but they were dissolved after the SHT, causing localized Mn enrichment in the\ud austenite. Potentiodynamic tests showed that the pitting potential (Ep) in the 304L\ud steel was not altered significantly after SHT. On the other hand, the value of Ep of\ud the 17Cr-6Mn-5Ni-1.5Cu steel decreased after SHT. This detrimental effect was explained\ud by the formation of Mn enrichment areas due to the solubilization of Mn-rich\ud precipitates, which promoted preferential Cl- adsorption in these regionsCAPESCNP