What are the common grades of stainless steel?

Stainless steel, with its excellent corrosion resistance, mechanical properties, and workability, is widely used in the food, chemical, construction, and medical industries. Different grades vary significantly in composition and performance, making correct identification and selection crucial for ensuring product quality.

Core classification of stainless steel: classification by organizational form

Specific Analysis
1. Austenitic Stainless Steel Series
(1) 304 (S30400)
Composition: 18% Cr, 8% Ni
Features: General-purpose stainless steel with good corrosion resistance, good welding performance, and moderate price
Applications: Kitchenware, architectural decoration, food processing equipment, chemical containers
Note: The most commonly used stainless steel grade, accounting for more than 50% of global stainless steel production
(2) 316 (S31600)
Composition: 16% Cr, 10% Ni, 2% Mo
Features: Contains 2% more molybdenum than 304, significantly improved corrosion resistance, especially chloride corrosion resistance
Applications: Marine environment equipment, chemical equipment, medical equipment, food processing equipment
Note: 316L (low carbon version) is more suitable for welded structures and reduces the risk of intergranular corrosion

Stainless Steel 304 Cap

316 Machined Part

2. Martensitic Stainless Steel Series
(1) 440C (S44004)
Composition: 16-18% Cr, 0.95-1.2% C
Features: High carbon, high chromium martensitic stainless steel, hardness can reach 58-60 HRC after heat treatment
Applications: Cutting tools, bearings, valves, precision instrument parts
Notes: It is one of the hardest grades of stainless steel, with excellent wear resistance
(2) 410
Composition: 13% Cr
Performance: Hardness can reach HRC45-50 after quenching, good plasticity when not quenched, can be stamped, taking into account both strength and processability
Applications: Valve spool, pump shaft, mechanical fasteners, tool holder (non-cutting edge part)

Stainless Steel 440C Bearing

 

3. Duplex stainless steel series
(1) S32205 (2205)
Composition: 22% Cr, 5% Ni, 3% Mo
Features: Ferrite + austenite duplex structure, strength twice that of 304, resistance to chloride stress corrosion
Applications: Marine engineering, chemical equipment, oil and gas pipelines, desalination equipment
Notes: Excellent overall performance, cost lower than 316L, corrosion resistance better than 304
(2) S32304
Composition: 23% Cr, 4.5% Ni, 0.3% Mo
Features: Low alloy duplex stainless steel, cost-effective, corrosion resistance close to S32205
Applications: Chemical industry, desalination, food processing, building structures
Remarks: Lower nickel content than S32205, lower cost
(3) S32750 (2507)
Composition: 25% Cr, 7% Ni, 4% Mo
Features: High alloy duplex stainless steel, excellent corrosion resistance, high strength
Applications: Extreme corrosive environments (such as deep sea, chemical industry, flue gas desulfurization)
Remarks: One of the most corrosion-resistant grades of duplex stainless steel

Comparison of Typical Application Scenarios

Key Performance Indicators and Testing Items for Stainless Steel
1. Physical Properties: Magnetism, density, thermal expansion coefficient, elastic modulus, and hardness
2. Chemical Composition Analysis: Grade identification, element content determination (e.g., Cr, Ni, Mo, C, etc.)
3. Mechanical Properties: Tensile strength, yield strength, elongation, impact toughness, fatigue strength
4. Processing Performance: Bending, flaring, flattening, and weldability testing
5. Corrosion Resistance: Intergranular corrosion, pitting, stress corrosion cracking, and salt spray testing
6. Nondestructive Testing: X-ray, ultrasonic, magnetic particle, and eddy current testing
7. Failure Analysis: Fracture analysis and corrosion product analysis
Industry Development Trends

• High Alloying: The application range of high-alloy grades such as S32750 continues to expand
• Environmental Protection: Research and development of low-nickel and low-chromium grades to reduce resource consumption
• Multifunctionality: New grades combining corrosion resistance, high strength, and ease of processing
• Customization: Stainless steel compositions can be customized to meet specific application requirements

Conclusion
There's no single optimal stainless steel grade, only the most suitable one. The versatility of 304, the corrosion resistance of 316, the cost-effectiveness of 430, the wear resistance of 440C, and the high strength of 2205 all address the needs of different applications. As a supplier of high-end nonferrous metals with over 20 years of production and export experience, FANMETAL not only offers cost-effective stainless steel products to overseas customers, but also other metal products such as tungsten alloys, nickel alloys, titanium alloys, and precious metals. Some of our products are currently exported to over 50 regions and countries, including Southeast Asia, Europe, the United States, the Middle East, and South Africa. If you have any questions about this product's details or delivery time, don't hesitate to contact us at admin@fanmetalloy.com.