LDRHAWKE
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If we are starting to see rust it is most likely it is because of lack of moly In Tesla special 30X
Austenitic Stainless Steels (200 and 300 Series)
Austenitic stainless steels are the most common family of stainless steels in use, with a market share of 75 percent as recently as 2004. As the name suggests, the microstructure is composed of the austenite phase. In the 300 series, this is achieved with about 16 to 22 percent chromium and 8 to 14 percent nickel. Although the nickel adds ductility, it is prone to a fluctuating commodity price, reaching $50,000 a ton in 2007 but now closer to $10,000 a ton. The 200 series, developed to get around the high price of nickel, replaces some nickel content with manganese and nitrogen.
The most commonly used austenitic grade is SS304. With its composition of 18 percent chromium and 8 percent nickel, it is sometimes referred to as 18-8 stainless. However, this designation isn’t recommended for general use, as there are tolerances in the allowable range of these elements that overlap with other grades. For example, SS316 is similar in chromium and nickel content, but it also has about 2 percent molybdenum for additional corrosion resistance.
These grades are prone to sensitization, a loss of alloy integrity. During cooling from welding or annealing, chromium carbide precipitates form at the microstructural grain boundaries. In these areas, the chromium feeds the carbide formation at the expense of the surrounding metal. With lower chromium content, the grain boundaries are at risk for corrosion.
Carbide precipitation can be reduced through the use of grades with lower carbon content (about 0.03 percent rather than 0.08 percent). Lower-carbon versions of austenitic grades are designated with the suffix L, such as 304L or 316L. Another way to prevent sensitization is to add titanium and/or niobium, which combine preferentially with carbon.
Austenitic Stainless Steels (200 and 300 Series)
Austenitic stainless steels are the most common family of stainless steels in use, with a market share of 75 percent as recently as 2004. As the name suggests, the microstructure is composed of the austenite phase. In the 300 series, this is achieved with about 16 to 22 percent chromium and 8 to 14 percent nickel. Although the nickel adds ductility, it is prone to a fluctuating commodity price, reaching $50,000 a ton in 2007 but now closer to $10,000 a ton. The 200 series, developed to get around the high price of nickel, replaces some nickel content with manganese and nitrogen.
The most commonly used austenitic grade is SS304. With its composition of 18 percent chromium and 8 percent nickel, it is sometimes referred to as 18-8 stainless. However, this designation isn’t recommended for general use, as there are tolerances in the allowable range of these elements that overlap with other grades. For example, SS316 is similar in chromium and nickel content, but it also has about 2 percent molybdenum for additional corrosion resistance.
These grades are prone to sensitization, a loss of alloy integrity. During cooling from welding or annealing, chromium carbide precipitates form at the microstructural grain boundaries. In these areas, the chromium feeds the carbide formation at the expense of the surrounding metal. With lower chromium content, the grain boundaries are at risk for corrosion.
Carbide precipitation can be reduced through the use of grades with lower carbon content (about 0.03 percent rather than 0.08 percent). Lower-carbon versions of austenitic grades are designated with the suffix L, such as 304L or 316L. Another way to prevent sensitization is to add titanium and/or niobium, which combine preferentially with carbon.
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