AISI 310S, UNS S31008, 1.4845 stainless steel
AISI 310S is a highly alloyed austenitic stainless steel used for high temperature service. It is a low carbon modification of AISI 310 with increased strength at temperatures above 1150°C known as heat resisting steel. The lower carbon content of AISI 310S does not reduce its high temperature strength compared with AISI 310, but it enhances its oxidation resistance properties and makes this grade more resistant against graphitization. Moreover, AISI 310S has good resistance to sulfidation and chloride-ion stress corrosion cracking.
AISI 310S is mostly used in petrochemical, paper, textile, dyes and food processing industry as well as in flue-gas desulfurization plants. This grade of stainless steel can be used in open-air corrosion applications if certain prerequisites for welding and fabrication processes are met.
AISI 310S has the chemical composition including C = 0.08%, Si = 1.50%, Mn = 2.00%, P = 0.045%, S = 0.030%, Ni = 23.00%, Cr = 24.00%, and N = 0.10%. This grade is produced in the following shapes: bar and tube.
Corrosion resistance properties of AISI 310S are enhanced thanks to its high nickel and chromium content as this grade is classified as a chrome-nickel austenitic stainless steel and has good resistance to oxidation and carburization in the high-temperature service. Sulfidation, performed in an atmosphere rich in sulfur chemistry and commonly linked to combustion equipment, may lead to accelerated corrosion processes and premature cracking in the components. This is where AISI 310S comes in handy – due to its good sulfidation resistance, it is an optimal choice for this kind of application.
AISI 310S is not hardenable by heat treatment and it can only be cold worked. While moderately severe cold-working can increase tensile properties and some of the other properties such as hardness and formability, it is usually not recommended due to work hardening and the high risk of cracking.
AISI 310S is widely used in heat exchangers, in the production of furnace parts, for the manufacture of selected food processing and dyeing equipment components, for the production of chimney liners and in many other engineering applications. Apart from its use in applications, AISI 310S can also be used in structural components or as an alternative to higher alloys when the cost is an issue.
In general, due to its austenitic structure, the weldability of AISI 310S is excellent, and it can be fusion welded using all conventional processes. Also, gas welding, spot welding, and seam welding can be used. When using welds, the pre- and post-weld heat treatments become essential for controlling the risk of microstructural changes and ensuring uniform metallurgical properties.
In conclusion, AISI 310S is ideal for applications that involve temperatures higher than 1150°C and where the grade does not need to be hardened by heat treatment. It is also used in the production of furnace parts, in heat exchangers, for the manufacture of selected food processing equipment components, for the production of chimney liners and in many other engineering applications. AISI 310S has good resistance to oxidation, sulfidation and carburization, and it also offers good weldability and multi-directional ductility.
