Cold-Rolled 321L Stainless Steel: Composition, Properties and Applications
Cold-rolled 321L stainless steel is a titanium-stabilized austenitic stainless steel belonging to the 300-series family, optimized for high-temperature corrosion resistance and intergranular corrosion prevention. Its core chemical composition (in line with international standards such as ASTM A240/A240M and GB/T 3280-2023) is as follows: chromium (Cr) 17.0%-19.0%, nickel (Ni) 9.0%-12.0%, titanium (Ti) ≥5×C (carbon content) and ≤0.70%, and carbon (C) ≤0.03%. The addition of titanium effectively fixes carbon atoms, avoiding the formation of chromium carbides at grain boundaries—this is the key difference from non-stabilized 304/316 stainless steels and the core reason for its excellent intergranular corrosion resistance.
In terms of mechanical properties, cold-rolled 321L shows outstanding performance after precision cold-rolling processing. According to test data from authoritative material laboratories (e.g., SGS, China National Iron and Steel Materials Test Center), its tensile strength reaches 515-655 MPa, yield strength (0.2% offset) is ≥205 MPa, elongation (in 50 mm gauge length) is ≥40%, and hardness (Brinell) is ≤217 HB. Compared with hot-rolled 321L, the cold-rolled version has a smoother surface (Ra ≤0.8 μm), higher dimensional accuracy (thickness tolerance ±0.02 mm), and enhanced fatigue resistance, making it suitable for scenarios requiring strict surface quality and structural stability.
Due to its unique properties, cold-rolled 321L is widely used in high-temperature and corrosive environments, mainly covering the following fields:
- Petrochemical and chemical industry: Used to manufacture heat exchangers, reaction kettles, and pipeline components that operate at 400-800°C (e.g., ethylene cracking units), as it can resist corrosion from organic acids, alkalis, and high-temperature steam without intergranular cracking.
- Aerospace and automotive industry: Applied in aircraft engine exhaust systems, automotive turbocharger casings, and exhaust manifolds—its high-temperature strength (maintaining ≥80% of room-temperature strength at 600°C) meets the requirements of high-heat parts.
- Power generation industry: Used for boiler tubes, steam pipelines, and condenser components in thermal power plants and nuclear power auxiliary systems, as it withstands cyclic thermal stress and corrosion from high-pressure water vapor.
- Food and pharmaceutical equipment: Suitable for high-temperature sterilization tanks, drying ovens, and conveying pipelines—its low carbon content (≤0.03%) and titanium stabilization avoid metal ion precipitation, complying with FDA and GMP standards.
It should be noted that cold-rolled 321L has limitations: its corrosion resistance to strong oxidizing media (e.g., concentrated nitric acid, chlorine gas) is inferior to 316L; and its cost is about 30%-50% higher than 304L, so it is not recommended for low-temperature, non-corrosive general structural parts (e.g., decorative panels, daily necessities) to avoid cost waste.
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