What are the unique alloy compositions of stainless steel coils
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www.80xycq.com | Release time:2025年09月29日
The unique alloy composition core of stainless steel coils is chromium (Cr) and nickel (Ni), combined with elements such as carbon (C), molybdenum (Mo), titanium (Ti), etc., forming diverse properties through different proportions to adapt to different usage scenarios (such as rust prevention, high temperature resistance, and corrosion resistance).
1. Core alloy composition: determines the basic characteristics of stainless steel
Chromium (Cr): The "rust resistant core" of stainless steel. When the chromium content is ≥ 10.5%, a dense chromium trioxide (Cr ? O3) passivation film will form on the surface of the steel, which can isolate air, moisture and contact with the interior of the steel, fundamentally preventing corrosion. This is the key component that distinguishes stainless steel from ordinary steel. The higher the content (such as 18%), the stronger the basic rust prevention ability.
Nickel (Ni): enhances the toughness and corrosion resistance of stainless steel. Nickel can optimize the stability of chromium passivation film, especially in low-temperature environments (such as -196 ℃) to maintain the toughness of steel and avoid low-temperature brittle cracking; Simultaneously enhancing the resistance of stainless steel to acid and alkali media, it is an important component of austenitic stainless steels such as 304 and 316 (the most commonly used types), with a typical content of 8% -10%.
2. Auxiliary alloy composition: Targeted strengthening of specific properties
Molybdenum (Mo): enhances the ability to resist chloride ion corrosion. Stainless steel (such as 316 type) with added molybdenum (usually 1.5% -3%) can effectively resist the corrosion of chloride ions in seawater, saltwater, and chemical solutions, avoiding "pitting corrosion" (local corrosion perforation), making it suitable for use in humid kitchen environments, outdoor or chemical scenes.
Carbon (C): Balancing "strength and processability". Carbon can enhance the hardness and strength of stainless steel, but excessive content (>0.1%) can reduce toughness and may combine with chromium to form "chromium carbide", damaging the passivation film and reducing rust prevention ability. Therefore, food grade and decorative grade stainless steel coils (such as 304) usually adopt low-carbon design (C ≤ 0.08%), taking into account rust prevention and processing requirements such as bending and cutting.
Titanium (Ti)/niobium (Nb): prevents "intergranular corrosion". In welding or high-temperature usage scenarios, carbon easily combines with chromium to precipitate chromium carbide, resulting in insufficient chromium content inside the steel and intergranular corrosion. Adding titanium (such as 321 type) or niobium (such as 347 type) can preferentially combine with carbon to form stable compounds, protecting chromium from loss, and is suitable for stainless steel coil applications that require welding (such as kitchen countertop splicing and pipeline production).
3. Other functional components: adapted to special scenario requirements
Manganese (Mn): partially replaces nickel to reduce costs. In 200 series stainless steel, manganese can replace some nickel (with a content of 5% -10%), maintaining a certain toughness and rust resistance. Although the overall corrosion resistance is weaker than 304, the price is lower and suitable for decorative stainless steel coils with low rust prevention requirements (such as billboards and simple storage).
Silicon (Si): enhances "high temperature resistance and oxidation resistance". Stainless steel with added silicon (content 0.5% -1.0%) can form a more stable oxide film in high-temperature environments (such as above 500 ℃), reducing high-temperature oxidation losses. It is suitable for stainless steel coils used in oven liners, high-temperature pipelines, and other scenarios.