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Stainless steel is widely used in industry and daily life for its corrosion resistance, strength and appearance. 304 and 316 are the most common austenitic stainless steel grades, but they differ significantly in performance and applications. Understanding their differences is key for material selection and cost control. 1. Core Difference: Chemical Composition The key distinction is molybdenum (Mo) content: – 304 (UNS S30400): Known as “18/8” stainless steel (18% Cr, 8% Ni), with little or no molybdenum (Mo ≤ 0.75%). – 316 (UNS S31600): Upgraded from 304, adding 2-3% molybdenum. It also has higher nickel content (10-14%) than 304. Molybdenum is the main reason for 316’s better performance. 2. Corrosion Resistance (Key Distinction) – 304: Performs well in most environments (air, fresh water, food processing, nitric acid). But it’s poor in chloride environments (seawater, salt spray, chlorine disinfectants) — easy to get pitting or cracking. It also resists strong acids (like hydrochloric acid) poorly. – 316: Molybdenum greatly improves chloride corrosion resistance (suitable for seawater, salt spray). It also resists more organic/inorganic acids (acetic acid, dilute sulfuric acid). It works well where 304 does, and protects in harsh environments where 304 fails. 3. Mechanical & Processing Properties – Mechanical properties: Similar tensile strength, yield strength and toughness at room temperature. 316 has slight high-temperature strength advantage, but not a key selection factor for most uses. – Processing: Both have high work hardening (need annealing during cold working like bending). 316 is “stickier” — harder to cut (faster tool wear). Both weld well, but 316 may need post-weld heat treatment for better corrosion resistance. 4. Typical Applications – 304: Cost-effective for regular environments — kitchen equipment, home appliances, interior decoration (non-coastal), tableware, general chemical equipment (weak acids/alkalis). – 316: For harsh environments — marine parts, coastal buildings, seawater desalination, chemical/petrochemical tanks/pipelines, medical equipment (316L, low-carbon version), food equipment cleaned with chlorine disinfectants. 5. Cost 316 is 30%+ more expensive than 304 (due to nickel and molybdenum). Choose 304 for regular use to save cost; use 316 in corrosive environments to avoid early failure and high maintenance costs. Summary 304 suit for universal, cost-effective for regular environments. 316 suits for corrosion-resistant upgrade (due to molybdenum), for harsh marine/chemical/medical scenarios.