Performance And Characteristics Of Stainless Steel 321
321 stainless steel is 18/8 austenitic stainless steel (304) stabilized with titanium. Intercrystalline corrosion will not occur after heating within the range of 425-850°C carbide precipitation temperature. 321 provides phase stability with high strength, oxidation resistance, and subsequent resistance to aqueous solution corrosion for applications up to temperatures of approximately 900°C.
The 321H is an improved version of 321 with a controllable high carbon content and high temperature strength.
The limitation of grade 321 is that the welding arc transition of titanium is not good, so it cannot be used as welding material. Therefore, the use of 347-Niobium also plays the role of carbide stabilization, but can be transferred by welding arc. Therefore, 347 is the standard welding material for 321 stainless steel welding. The 347 is used only occasionally as the base material.
Like other austenite, 321 stainless steel has excellent forming and welding properties, easy to bend or roll forming, and does not require post-weld annealing. Stainless steel 321 has excellent toughness even at low temperatures. Stainless steel 321 polishing effect is not good, so it is not recommended for decorative purposes.
304L is more readily available in most product forms, so 304L is usually preferred if only post-weld resistance to intercrystalline corrosion is required. However, the thermal strength of 304L is less than 321, and it is not the best choice if it requires a resistance of about 500°C or more.
Corrosion resistance
Equivalent to 304 stainless steel in annealed condition, excellent corrosion resistance in 425-900°C temperature range. Pitting and crevices occur in warm chlorinated environments and stress corrosion cracking occurs at temperatures above about 50°C. Tolerances of up to 200mg/L of chloride in drinking water (at room temperature) are reduced to about 150mg/L at 60°C.
Heat resistant performance
Excellent antioxidant properties, operating temperatures up to 900°C (intermittent use) and 925°C (continuous use). These grades perform well in the temperature range of 425 to 900°C, especially under conditions of subsequent aqueous solution corrosion. The 321H has high thermal strength and is particularly suitable for high temperature structural applications.
Typical applications
Expansion joints, bellows, furnace components, heating tubes, heat exchangers, high temperature strainers, burner pipes and spiral welded pipes of flue, etc.
