Development and in-depth electrochemical performance evaluation of economic lean duplex stainless steel alloys

Stainless steels and Ni base alloys are widely used in different industrial applications due to their excellent corrosion resistance and mechanical properties. Along with Ni and Cr, many other alloying elements such as Si, Cu, Mn, Sn, Mo, and W etc. are used depending on final application requirements. Duplex stainless steels are an important class of materials, which have widespread applications because of their high strength and superior corrosion resistance. They are also less costly in some cases than austenitic stainless steels, owing to low Ni content. However most common duplex stainless steel alloys still have some amount of Ni (3~7 wt.%), which makes them still costly. Another problem is the formation of 2ndry phases such Sigma phase, which makes the material brittle and susceptible to corrosion in many environments. There have been few efforts to develop stainless steels with and without Ni in which Ni was replaced with Mn (up to 10%). Though such alloys overall showed higher strength and toughness, however Mn content was too high and it has been reported already that Mn content above around 6% can have a significant effect on the corrosion resistance properties. Keeping this in mind, in this study, we will develop a new set of lean duplex stainless steels (LDSS) by varying Mn, Mo, W, Si etc. and will carry out in-depth investigations on the electrochemical performance of these in-house developed LDSS alloys