Differences Between 304 and 316 Stainless Steel Castings

When designing a metal component with investment casting process, many people would like to select stainless steel as the casting material for its exceptional resistance to corrosion.

304 and 316 are the two of the most widely used stainless steel casting grades in the world. Selecting the most optimal grade for stainless steel investment casting can mean longer lasting performance, especially in challenging corrosive environments. For 304 and 316 stainless steels, the presence of molybdenum is mainly what makes them different. The additional alloy increases corrosion resistance, especially in high-saline environments where exposure to chlorides is common.

Differences Between 304 and 316 Stainless Steel Castings

304 Stainless Steel Casting

304 stainless steel contains between 16 and 24 percent chromium and up to 35 percent nickel. It also contains small amounts of carbon and manganese. 304 stainless steel is the most common form of stainless steel casting used around the world—specifically a form called 18-8, or 18/8, stainless steel, which contains 18 percent chromium and 8 percent nickel (as the name implies).

304 stainless steel is an austenitic steel, as is defined by its molecule structure. Austenitic stainless steel castings offer a solid balance of strength and workability across a wide temperature range, making it useful for many applications.

304 stainless steel castings are often used for kitchen and food applications, specifically beer brewing, milk processing and wine making. It is also common in architectural designs, chemical containers, water filtration screens, ect.

Note: High saline environments such as outdoor coastal areas or cold, icy areas that receive regular exposure to de-icing salts may be unsuitable for 304 stainless steel castings.

316 Stainless Steel Casting

316 stainless steel is the second-most common form of stainless steel castings used in the world. It is characterized by the addition of molybdenum—about 2 to 3 percent of total composition—which ensures a higher degree or corrosion resistance.

Other 300-series stainless steel castings can contain up to 7 percent molybdenum. It is especially useful where 304 stainless steel casting fail—i.e. where chlorides and/or other industrial chemicals are common.

For outdoor applications, 316 stainless steel castings are ideal for high moisture environments with regular salt exposure, such as glass spider fittings, glass spigots, etc. Often referred to as “marine-grade” steel, 316 stainless steel castings are used often for marine hardwares. In addition to applications typical for 304 stainless steel, 316 grade stainless steel castings are common in laboratories, coastal buildings and architecture and boat fittings.

It’s also a useful material for manufacturing environments where exposure to corrosive chemical solvents is common. Medical applications are also widespread, as 316 stainless steel castings are highly-unreactive, which helps minimize risk of contamination.

As the professional stainles steel foundry in China, CFS can make all types of stainless steel castings, not only limited to 304 and 316, but can also make stainless steel investment castings with other grades, such as 17-4 ph, CG8M, 2205, etc. Any project on stainless steel casting, pls contact us!

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