As with most industries, choosing the best stainless steel alloy for a given process or equipment depends largely on specific requirements. However, as a rule of thumb, the following features can help you further hone your initial material choice and find the perfect combination of corrosion resistance, strength and cost.
Austenitic stainless steel provides better durability in the heat affected zone when welded, is non-magnetic, and can be hardened by cold work. Common grades include 303,304/304L, 321, 347, N60, 316/316L, 316L-2.5% MinMo, 317L, 317LMN and other high nickel or high molybdenum alloys.
Ferritic stainless steels have better solderability and lower price points, but generally have lower corrosion resistance. This makes them more suitable for low-risk processes such as alkaline grinding sections and dryers. Common grades include 430 and 3CR12.
Martensitic stainless steel is harder and stronger than many austenitic stainless steels, making it ideal for use in areas where wear and tear are critical factors. Common grades include 410, 416, 420, 440C, and 16Cr5Ni 1Mo.
Precipitate hardened stainless steel is ideal for assemblies and bolts. However, they may weaken with welding, so be sure to consider implementation and installation requirements. Common grades include 15-5 and 17-4.
Duplex stainless steel is becoming more and more popular in pulp and paper industry processes due to its special corrosion resistance, sand or abrasive resistance and flexible implementation schemes. Cast-molded duplex steel can often replace smaller stainless steel alloys, while forged duplex steel is the popular choice to replace carbon steel, cladding and welded cover digesters. Commonly used brands include 2304,2205,329,2507,3RE60.