A new resource-saving, low chromium and low nickel duplex stainless steel 15Cr-xAl-2Ni-yMn

摘要

A new family of resource-saving, low Cr and low Ni duplex stainless steels, with compositions of 15Cr-xAl-2Ni-yMn (x- 1.2-2.8, y = 8-12, wt.%) has been developed by examining the effect of Al and Mn on microstructure, mechanical property and corrosion property. The results show that 15Cr-l.2Al-2.0Ni-8Mn and 15Cr-2.0Al-2.0Ni-10Mn alloys have a balanced ferrite-austenite relation and that 15Cr-2.8Al-2.0Ni-12Mn alloy has a primary ferrite phase structure. The ferrite volume fraction increases with the solution treatment temperature and Al content while decreases with Mn content. No precipitate was found after solution-treated at 750 ℃ for 30 min. 15Cr-1.2Al-2.0Ni-8Mn alloy has a strong strain hardening effect, and 15Cr-2.0Al-2.0Ni-10Mn alloy has a good TRIP effect. Both of the 15Cr-l.2Al-2.0Ni-8Mn and 15Cr-2.0Al-2.0Ni-10Mn alloys have excellent impact toughness at low temperature with the impact energy higher than 125 J at -40℃. The pitting corrosions always occur in austenite phase. Among the designed alloys, 15Cr-1.2Al-2.0Ni-8Mn and 15Cr-2.0Al-2.0Ni-10Mn are found to be excellent alloys with a proper phase proportion and a better combination of superior mechanical property and good pitting corrosion resistance.