Stainless Steel Grades Chart: Properties, Applications, and Comparison

Table of contents:

• Overview
• Stainless Steel Grades Classification
  1. Austenitic Stainless Steels (300 Series)
  2. Ferritic Stainless Steels (400 Series)
  3. Martensitic Stainless Steels
  4. Duplex and Super Duplex Steels
  5. Precipitation-Hardening (PH) Stainless Steels
• Chemical Composition and Properties of Stainless Steel Grades
• Stainless Steel Grades Chart
• Comparison of Popular Stainless Steel Grades
• Applications of Stainless Steel by Grade
• Choosing the Right Stainless Steel Grade
• Conclusion

Stainless steel is widely used in industries due to its versatility, strength, and corrosion resistance. However, different grades offer varying properties like mechanical strength and suitability for specific applications. Understanding these grades is essential for industries such as construction, automotive, and food processing, where selecting the right material ensures durability and performance.

Stainless steel grades are standardized by organizations like AISI, ASTM, EN, and JIS, allowing manufacturers to maintain consistency. Grades like 304 stainless steels are known for their adaptability and corrosion resistance, while 316 stainless steel provides enhanced resistance to chlorides, making it suitable for marine environments.

These grades are classified based on their chemical composition, which includes elements like chromium, nickel, and molybdenum. This influences key properties such as tensile strength, elongation, and hardness, crucial for industrial applications. Austenitic stainless steels (300 series), for instance, are valued for their high levels of chromium and nickel, offering excellent corrosion resistance.

Must Read: Difference between 304 and 316 stainless steel

Stainless Steel Family Classification

Stainless steel can be grouped into different families based on its microstructure:

1. Austenitic Stainless Steels (300 Series): These are the most common stainless steels, known for their excellent corrosion resistance. Examples include Grade 304 and Grade 316, used in kitchen equipment, food processing, and marine applications.
2. Ferritic Stainless Steels (400 Series): These contain less chromium and no nickel, making them less corrosion-resistant but more cost-effective. Grade 430 stainless steel is widely used in domestic appliances.
3. Martensitic Stainless Steels: Known for their strength and hardness, these are used in cutlery, tools, and surgical instruments. Grade 410 and Grade 420 are examples of this family.
4. Duplex and Super Duplex Steels: These steels combine austenitic and ferritic structures, offering high strength and corrosion resistance. They are ideal for the oil and gas industry.
5. Precipitation-Hardening (PH) Stainless Steels: These steels can be heat-treated to enhance their strength. Grade 630 is a common type, used in high-performance applications like aerospace.

Chemical Composition and Properties of Stainless Steel Grades

Chemical Composition and Key Elements:

• Chromium (Cr): Essential for corrosion resistance. Forms a passive oxide layer on the steel’s surface that prevents further oxidation. Higher chromium content enhances protection against rust and environmental degradation.
• Nickel (Ni): Improves ductility and toughness, allowing stainless steel to maintain strength and flexibility at low temperatures. Nickel also boosts oxidation resistance and supports the stability of the protective oxide layer formed by chromium.
• Molybdenum (Mo): Increases resistance to pitting and crevice corrosion, especially in chloride-rich environments. Found in Grade 316, molybdenum enhances performance in marine and coastal applications.

Examples of Stainless Steel Grades:

• Grade 304: Contains approximately 18% chromium and 8% nickel, offering excellent general corrosion resistance. Commonly used in food processing, architecture, and household applications.
• Grade 316: Contains 16-18% chromium, 10-14% nickel, and 2-3% molybdenum, providing superior resistance to chlorides and harsh environments. Ideal for marine, chemical, and coastal industries.

Stainless Steel Grades Chart

A detailed chart is essential for understanding the differences between various stainless steel grades. Below is a table that highlights the chemical composition, tensile strength, and hardness of common grades.

This table provides a quick reference for comparing the performance of popular grades like 304, 316, and 410 in terms of strength, elongation, and resistance to heat and corrosion.

Comparison of Popular Stainless Steel Grades

304 vs 316 Stainless Steel:

• Both 304 and 316 are austenitic stainless steels, known for their high chromium content, providing excellent general corrosion resistance. Grade 304 is more economical and is widely used in food processing and general-purpose applications where exposure to harsh environments is limited.
• Grade 316, with 2-3% molybdenum, offers superior resistance to pitting and crevice corrosion, making it ideal for chloride-heavy environments like coastal areas and chemical plants.

410 vs 420 Stainless Steel for Cutlery and Tools:

• Grade 410 is a martensitic stainless steel that offers good ductility, machinability, and moderate corrosion resistance, making it suitable for kitchen utensils and other general applications.
• Grade 420, with its higher carbon content, can be hardened to a greater extent, providing higher hardness and wear resistance, which makes it ideal for cutting tools, surgical instruments, and blades.

Duplex vs Super Duplex Stainless Steels:

• Duplex stainless steels have a balanced austenitic-ferritic structure, providing a combination of high strength and excellent resistance to stress corrosion cracking, often used in industries where moderate corrosion is a concern.
• Super Duplex steels contain higher amounts of chromium, nickel, and molybdenum, which boost their performance in extreme environments like offshore oil rigs, offering enhanced resistance to chloride-induced stress corrosion and high temperatures.

Applications of Stainless Steel by Grades

SS 304 grade Usage in Food Processing and Architecture:

1. Due to its excellent formability, weldability, and resistance to various acids and alkalis, Grade 304 is highly suitable for environments requiring hygiene, such as food processing equipment and kitchen sinks.
2. The high chromium (18-20%) and nickel (8-10.5%) content ensures corrosion resistance, making it ideal for architectural applications like facades, capable of withstanding temperature variations.

SS 316 Grade Usage in Marine and Chemical Industries:

1. Grade 316 stainless steel is preferred in marine environments and chemical industries for its superior pitting and crevice corrosion resistance, thanks to the addition of molybdenum (2-3%).
2. Its excellent resistance to chloride ion attack makes it ideal for seawater applications, chemical reactors, and environments exposed to aggressive chemicals.

SS 430 Grade Usage in Automotive and Domestic Environments:

1. Grade 430, a ferritic stainless steel, is more cost-effective due to its lower nickel content, making it suitable for applications like automotive exhaust systems that require moderate corrosion resistance under high temperatures.
2. In domestic environments, Grade 430 is widely used in appliances like refrigerators and dishwashers for its stress corrosion cracking resistance, combined with its high chromium content (16-18%) for oxidation resistance.

Choosing the Right Stainless Steel Grades

Choosing the correct stainless steel grade depends on several factors:

1. Corrosion Resistance: If your project involves exposure to corrosive environments, Grade 316 is ideal. For general applications, Grade 304 may suffice.
2. Mechanical Properties: For high-strength applications like tools, Martensitic steels such as Grade 420 provide the necessary hardness.
3. Cost Considerations: Ferritic stainless steel like Grade 430 offers a more affordable option for non-critical environments.

For example, a marine engineering firm would benefit from 316 stainless steel, while an automotive manufacturer might choose Grade 430 for exhaust systems.

For more information you can check out this PDF (click here)

Conclusion

Understanding the stainless steel grades chart is critical for choosing the right material for your project. Stainless steel’s versatility, corrosion resistance, and mechanical properties make it essential across industries like food processing, construction, and chemical engineering. Each grade offers unique advantages: 304 is widely used due to its affordability and corrosion resistance, while 316 provides enhanced protection against chlorides, making it ideal for marine and chemical environments. As technology advances, stainless steel continues to evolve, with innovations in alloy compositions and processing techniques driving its applications in areas such as medical devices, aerospace, and sustainable construction. This ongoing innovation ensures stainless steel remains a reliable and durable choice for industries worldwide. By understanding the specific properties of each grade, you can select the most suitable option, optimizing both performance and cost-efficiency for your projects.

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Author: Anirban Sinha

A product manager with a writer’s heart, Anirban leverages his 6 years of experience to empower MSMEs in the business and technology sectors. His time at Tata nexarc honed his skills in crafting informative content tailored to MSME needs. Whether wielding words for business or developing innovative products for both Tata Nexarc and MSMEs, his passion for clear communication and a deep understanding of their challenges shine through.