It is the most common grade, after 304 to be used in the market, basically due to its properties and availability at the same time. It replaces grade 304 in regard to corrosion resistance with better strength at higher temperature. The material has specifically better chloride immunity and resistance to industrial solvents.
The chemical composition consists of adequate chromium content (18%), nickel content (14%), and carbon content (0.08%) along with balance in properties like corrosion resistance and ductility. The grade is non-magnetic due to its microstructure at all temperatures. Hence, the grade negligibly responses to magnetic field and is commonly used in applications where metal with non-magnetic properties are required. However, after welding, the metal might become slightly magnetic.
Molybdenum is efficiently used to resist salt in seawater. The molybdenum addition to the grade effectively resists the corrosive action of the salt in seawater. Hence, the chromium-molybdenum alloy SS 316 is widely used in marine applications. Also, this property makes the grade useful in applications near coastal areas. The buildings near the sea, especially in cities, uses the grade 316 in their applications, like railings, gates, etc. The easy fabrication and sound features make the grade hard to miss. The addition of molybdenum has also resulted in increased resistance to pitting in general chloride ion solution and increased strength at elevated temperatures. The grade has another version with lower carbon content and other chemical composition, same as SS 316L. This version is used efficiently in the applications where carbide precipitation at the grain boundary might be an issue. During welding, the unwanted carbide precipitation can be avoided using the low carbon version.
The nitrogen content in this version retains its mechanical properties. The grade has a fine creep resistance which can be used at elevated temperatures even under thermal cyclic loads. A creep stress of 35 MPa will be induced after 10000 hours of use for 1% creep at 750°C. An exceptional oxidation resistance is shown by the grade with continuous service around 925-930°C, and with intermittent service, the grade can be conveniently used around 860- 870°C. Neither service nor slow cooling should be done in the range of 425- 870°C to avoid sigma phase embrittlement. The continuous use in this range would affect the corrosion resistance of the grade to wear off. The 316L grade can sometimes be used in this case since it avoids granular carbide precipitation.
