With regard to general corrosion and oxidation, stainless steels with 16-18% Cr passivate and have good resistance to aqueous corrosion and various types of other acidic or corrosive environments at room temperature and up to about 200-300 °C.2 Additions of molybdenum give type 316 better resis­tance to pitting and acidic attack. Effects of stress can aggravate corrosion resistance, and types 304 or 316 processed to have Cr-carbides precipitated along grain boundaries can suffer from stress-corrosion­cracking (SCC), which causes grain-boundary cracking at reduced ductility to embrittle the steel. Lower carbon steels (304LN, 316L) tend or reduce or elimi­nate SCC, as do the stabilized stainless steel grades such as 321 and 347, which form TiC or NbC carbides to prevent Cr-carbide precipitation at grain bound­aries. Exposure to supercritical water at 300 °C and above can be very corrosive, and cause oxidation of
austenitic stainless steels.16 Generally, 300 series aus­tenitic stainless steels have minimal oxidation in air at 500 °C and below, but oxidation and the protective behavior of chrome-oxide scales become a concern at 550-600 °C and above. Finally, 300 series steels such as types 304 and 316 tend to show little or no corrosion and behave quite well in liquid-metal sodium envir­onments at 650 °C and below. More detailed informa­tion on austenitic stainless steels and their corrosion behavior in aqueous environments, oxidation at ele­vated temperatures, and behavior in liquid metals such as sodium is available in other chapters of this publication, or elsewhere.