Why 316 Stainless Steel Bolts Are More Expensive than 304 Bolts

2025-09-24 16:49:19

1. Material Composition Differences: The Addition of Molybdenum (Mo) Is the Core Factor

• 304 Stainless Steel: Basic composition is 18% Chromium (Cr) + 8% Nickel (Ni). It is a general-purpose austenitic stainless steel with lower cost.

• 316 Stainless Steel: Based on 304 but with an additional 2%–3% Molybdenum (Mo), and slightly higher Nickel content (10%–14%).

• Key Factor: Molybdenum is a rare and expensive metal (global average price around USD 45,000/ton), which directly increases raw material costs.

• Impact: The addition of Mo improves corrosion resistance, especially in chloride environments (such as seawater and acidic media), but increases raw material cost by about 20%–30%.

2. Performance Advantages: 316 Is More Reliable in Harsh Environments

• 304: Suitable for general environments (such as freshwater, mild acids), but prone to rust in high-salt, strong-acid, or chloride-rich conditions (such as marine or chemical environments).

• 316: Molybdenum contributes to a more stable passive film, enhancing resistance to pitting and crevice corrosion by over 30%. Particularly suited for marine engineering, medical devices, etc.

• Mechanical Properties: With Mo strengthening, 316 has higher tensile strength and hardness, making it better for high-load and high-wear applications (e.g., bolts under vibration or high pressure).

• High-Temperature Stability: Above 80 °C, 316 has a lower oxidation rate compared with 304.

3. Price Differences: Combined Impact of Raw Materials and Processing Costs

• Raw Material Costs: 304 stainless steel plates cost about RMB 15,000–20,000/ton, while 316 plates cost about RMB 21,000–26,000/ton, a 30%–40% difference.

• Molybdenum Contribution: Mo accounts for 15%–20% of 316’s total cost, and its price fluctuates significantly (e.g., Mo prices rose by over 50% in 2023).

• Processing Difficulty: Due to higher hardness, machining 316 (e.g., cutting, thread forming) causes faster tool wear and reduces production efficiency by about 10%–15%.

4. Application Scenarios and Market Demand

• 304 Bolts: Widely used in construction, furniture, and general equipment in non-corrosive environments. Demand is high, standardization reduces cost.

• 316 Bolts: Used in highly corrosive and high-reliability environments (such as ships, chemical pipelines, medical equipment), often requiring stricter certifications (e.g., ISO 3506), with higher added value.

• Example: Bolts in seawater desalination plants—304 may corrode within months, whereas 316 can last for years, significantly reducing maintenance costs.

5. Purchasing Recommendations: Choose According to Actual Needs to Avoid Waste

• Choose 304: For daily construction, indoor furniture, and non-acidic environments—very cost-effective.

• Choose 316: For contact with saltwater, acidic/alkaline media (e.g., food processing equipment, coastal facilities); high-temperature and high-pressure conditions (e.g., boilers, energy equipment).