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Which industries require GMP cleanrooms?
2025-03-14
Selecting Appropriate Stainless Steel Frame for Cleanroom:
304, 316, 304L, 316L
Definition of Stainless Steel:
Stainless steel refers to a type of steel characterized by its primary properties of resistance to rust and corrosion, with main components of iron, chromium, nickel, and other alloy elements, and a chromium content of at least 10.5%, and a maximum carbon content of not exceeding 1.2%. Stainless steel also possesses good toughness, strength, and plasticity, and can be shaped and processed by cold working, hot working and welding.
Classification of Stainless Steel:
Stainless steel can be classified differently according to its elemental structure, chemical composition and purpose.
According to different elemental structure, stainless steel can be divided into:
â–ºAustenitic Stainless Steel: Mainly composed of austenite, non-magnetic, mainly strengthened by cold working (this may lead to slight magnetism). 18-8 stainless steel is a typical type of austenitic stainless steel, containing about 18% chromium and 8% nickel, normally including grade 304, 316, etc. Austenitic stainless steel is the largest variety of stainless steel, accounting for about 70% of the market share. Austenitic stainless steel has excellent corrosion resistance and processing properties, and is often used to make equipment and mechanical accessories in chemical industrial, light industrial, medical and other fields (cleanroom equipment and pipe fittings are usually made of this type of stainless steel).
â–ºFerritic Stainless Steel: Mainly composed of ferrite, it is magnetic, and generally cannot be hardened by heat treatment. However, cold working can make it slightly strengthened. Ferritic stainless steel contains 12% to 18% chromium, while the carbon content is less than 0.2%. Common grades include 409, 430, etc., Its corrosion resistance is not as good as Austenitic stainless steel;
â–ºFerritic-austenitic (Duplex) Stainless Steel: A type of stainless steel composed of both ferrite and austenite, combining the advantages of both, with magnetic properties, and can be strengthened by cold working. Common grades include 2205, 2507, 2304, etc.
â–ºMartensitic Stainless Steel: A stainless steel mainly composed of martensite, with magnetic properties and can have its mechanical properties adjusted by heat treatment. Martensitic stainless steel contains 12~18% chromium. Common grades include 410, 420, etc.;
Stainless steel can be classified based on its main chemical composition or the presence of certain characteristic elements, into categories such as chromium stainless steel, chromium-nickel stainless steel, chromium-nickel-molybdenum stainless steel, ultra-low carbon stainless steel, high molybdenum stainless steel, and high-purity stainless steel.
Differences between 304 and 316 Stainless Steel:
Chemical composition and properties: 304 stainless steel contains approximately 18% chromium and more than 8% nickel, while 316 stainless steel includes an additional 2% molybdenum. The addition of this molybdenum element significantly enhances the corrosion resistance of SS316, particularly in resisting chloride corrosion and heat.
In terms of food-grade applications, SS304 complies with many national and international standards and is widely used in food contact applications such as cutlery, kitchen utensils, etc. It has good corrosion resistance and moderate cost, making it the preferred material for many daily necessities. On the other hand, due to its higher corrosion resistance and heat resistance properties, 316 is commonly used for medical equipment and high-end kitchen utensils.
Price-wise, because of more content of alloy elements, the cost of producing SS316 is usually higher than that of SS304. Therefore when selecting materials for specific applications, decisions should be made based on both actual needs and budget.
To sum up, SS304 is a versatile and affordable material suitable for most daily applications, while SS316 has better corrosion resistance and heat resistance, especially in the face of chloride, etc. It shows better performance in highly corrosive environments, so it is more suitable for production applications in this regard.
Differences between 304 and 304L Stainless Steel:
Composition differences: The carbon content of 304L stainless steel is lower, usually below 0.03%, while the carbon content of 304 stainless steel is below 0.08%. The low carbon design makes 304L stainless steel have better resistance to intergranular corrosion performance during welding process. Especially after welding or stress relief, its anti-grain boundary corrosion ability is better.
Performance differences: Due to the difference in carbon content, 304 and 304L stainless steel also show certain differences in mechanical properties. The strength and hardness of 304 stainless steel are generally higher than those of 304L. But in some applications where lower strength and better toughness are required, 304L stainless steel is more suitable.
In terms of price, since the production process of 304L stainless steel is more complex and requires stricter control and testing, its price is also higher than that of 304 stainless steel.
To sum up, the choice of 304 or 304L stainless steel should be decided according to the specific application scenarios and needs. For example, when the requirements for material strength and hardness are high, 304 stainless steel can be selected; and when welding performance and toughness are required, 304L stainless steel can be selected.
Differences between 316 and 316L stainless steel:
Chemical composition: 316 stainless steel contains 17-20% chromium, 11-14% nickel and 2-3% molybdenum, while 316L stainless steel contains 16-18% chromium, 10-14% nickel and 2-3% molybdenum. The carbon content of 316L stainless steel is lower, usually below 0.03%, while the carbon content of 316 stainless steel is around 0.08%.
Corrosion resistance: Both have good corrosion resistance and can resist corrosion from most chemical media, including acids, alkalis, and salts. However, due to the lower carbon content of 316L stainless steel, it has better intergranular corrosion resistance in the welding process, making it more suitable for applications in special environments such as seawater environments.
Strength and hardness: Due to the lower carbon content of 316L stainless steel, its strength and hardness are relatively lower, but it has better toughness. 316 stainless steel has a higher carbon content, so it has higher strength and hardness.
Welding performance: 316L stainless steel has better welding performance due to its lower carbon content, reducing the risk of intergranular corrosion. 316 stainless steel may encounter from intergranular corrosion during welding.
To sum up, the choice of stainless steel material depends on the specific application needs and environmental conditions. For example, for applications requiring higher corrosion resistance and better welding properties, 316L stainless steel may be a better choice. For applications requiring higher strength and hardness, 316 stainless steel may be more suitable.
Application areas: Due to the differences in composition and performance, 304 and 304L stainless steel have different application areas. 304 stainless steel is widely used in food processing equipment, medical devices, architectural decoration, automotive parts, etc., due to its good corrosion resistance and formability. 304L stainless steel is more suitable for occasions that require high welding performance, such as large building structures, chemical equipment, oil and natural gas pipelines and other fields that require a large amount of welding.
To sum up, the choice of stainless steel material depends on the specific application needs and environmental conditions. For example, for applications requiring higher corrosion resistance and better welding properties, 316L stainless steel may be a better choice. For applications requiring higher strength and hardness, 316 stainless steel may be more suitable.
