Influence of sinter-cooling rate on intergranular corrosion of powder metallurgy superaustenitic stainless steel

Abstract

Powder metallurgy superaustenitic stainless steel sintered in N 2 -H 2 atmosphere (95%-5%) was obtained. Three different processes were applied by controlling the sinter-cooling rate (furnace, gas and water). Intergranular corrosion resistance was evaluated. Furthermore, microstructure, density, porosity, macro-and microhardness were investigated. Microstructures were characterised by optical microscopy and scanning electron microscopy with energy dispersive analysis of X-rays. Intergranular corrosion behaviour was evaluated by immersion and by single and double loop electrochemical potentio-kinetic reactivation tests. The superaustenitic steel after fast cooling by water quenching showed the best intergranular corrosion behaviour, the highest microhardness values and the most homogeneous microstructure.

Effects of Debinding and Sintering Atmosphere on Properties and Corrosion Resistance of Powder Injection Molded 316 L - Stainless Steel

“…It may be due to the fact that presence of H 2 minimized the formation of chromium oxide. In contrast to carbides, the presence of nitrides at the sample surface reduced corrosion by decreasing the number of open pores and dissolving the N 2 gas within the matrix, which improved corrosion resistance (García et al 2007;Martin et al 2014). These observations were confirmed by the results of the weight loss measurements and atomic absorption analysis.…”