Stainless steel is among the most popular materials found in industries everywhere. Its strength, rust resistance and durability enable it to be used in various settings. However, not all grades of stainless steel are identical. Every type possesses certain attributes that qualify them for various uses. Whether the application involves chemicals, seawater, or high pressure, selecting the right stainless steel grade is crucial. Using the wrong type can lead to corrosion, failure, and extra costs in the long run. Depending on the working conditions and expected performance, the right grade must be matched to the application. The four commonly used grades of stainless steel that are the focus of this blog are 304, 316, 904L, and Duplex. We will examine their ideal uses, mechanical strength, corrosion resistance, and chemical makeup.
What Are Stainless Steel Grades?
Stainless steel grades categorise alloys based on key elements like chromium, nickel, and molybdenum. Molybdenum increases resistance to chemicals and chloride corrosion, nickel adds strength, toughness and heat resistance and chromium prevents corrosion by creating a protective layer. There are three types of stainless steel structures like duplex (a combination of austenitic and ferritic, combining strength and high corrosion resistance), ferritic (magnetic, less corrosion-resistant, more economical), and austenitic (non-magnetic, easy to form, includes grades 304, 316, and 904L). These grades guarantee uniform material qualities across the globe by adhering to international standards like AISI, ASTM, EN, DIN, and JIS.
Stainless Steel 304 – The Everyday Performer
Stainless Steel 304 is the most widely used stainless steel grade, known for its versatility and balanced properties. Often called 18/8 stainless steel it has about 8% nickel and 18% chromium. Since it is non-magnetic when annealed, it can be used in a variety of non-electrical applications. It is frequently used in fabrication processes because of its easy formability and weldability due to its moderate tensile and yield strength.
There are many uses for 304, particularly in the food and beverage industry. Equipment such as sinks, tables, storage tanks and surfaces used for food preparation. It is also utilized in ornamental architectural components like wall cladding, elevator panels, and railings because of its appealing finish and resistance to corrosion. It works well with mild chemical handling systems and process tanks in industrial settings. The most common forms of stainless steel 304 is available in the market, including sheets, coils, plates, and round bars.
Stainless Steel 316 – Enhanced Marine Resistance
Stainless Steel 316 is similar in composition to 304 but includes an additional 2 to 3 percent molybdenum. It is also non magnetic and possesses good weldability and formability. 316 is suitable for conditions where moisture, salt or chemical exposure is anticipated. It is used in marine applications including boat fittings, coastal building structures, and dock hardware. In the pharmaceutical and medical industries, 316 is used to make cleanroom equipment, surgical tools, and processing machines because it withstands repeated cleaning and sterilisation. Water treatment systems, food processing lines and chemical storage also use it. 316 sheets, 316L coils, and 316 plates are the most popular types of this grade. Because it lowers the chance of corrosion in welded joints, the low-carbon version, 316L, is especially helpful when welding is necessary.
Stainless Steel 904L – High End Corrosion Resistance
The high-performance austenitic stainless steel 904L has a high nickel and molybdenum content and a low carbon content. Because it normally contains 4–5% molybdenum and 23–28% nickel it has exceptional resistance to strong reducing acids like phosphoric and sulfuric acid. This grade is intended for use in sectors of the economy where exposure to harsh chemicals is frequent. It works well in chemical processing facilities, especially in machinery that comes into contact with acidic solutions. Because 904L is resistant to stress corrosion cracking and seawater corrosion, it is used for pressure vessels, heat exchangers and pipework on offshore oil platforms. It is used in pulp and paper systems, gas scrubbers, and some pharmaceutical equipment. There are several product forms for 904L stainless steel, such as coils, sheets, and plates. Depending on the specifications for strength and surface finish, these are produced in both cold-rolled and hot-rolled forms.
Duplex Stainless Steel – Strength Meets Performance
Duplex grades like Duplex 2205 has the characteristics of ferritic and austenitic stainless steel grades. They have a dual-phase structure, which leads to excellent mechanical strength, normally more than twice that of 304 or 316 and good resistance to numerous types of corrosion. Duplex 2205 has approximately 22% chromium, 5% nickel and 3% molybdenum and nitrogen to further enhance the strength and corrosion resistance. The most significant benefits of Duplex stainless steel are resistance to pitting, crevice corrosion, and stress corrosion cracking, particularly in chloride-rich situations. It is used where both strength and corrosion resistance are required. Industries such as oil and gas, petrochemicals, pulp and paper, and desalination plants often rely on Duplex for long-term reliability. It is especially suited for pressure vessels, structural components, and piping systems exposed to harsh media or high pressure. Duplex stainless steel is available in several forms such as structural sheets, heavy-duty plates, and industrial coils.
Stainless Steel Sheets, Plates and Coils – Grade wise Application
Sheets
Thin and flexible, stainless steel sheets are easy to cut and form. They’re used in kitchen backsplashes, panels, cladding, and industrial enclosures. Grades like 304 sheets, 316 sheets, 904L sheets and Duplex are all available.
Plates
Stainless steel plates are thicker and stronger, making them ideal for heavy-duty applications like pressure vessels and marine construction. Grade 316 offers excellent corrosion resistance for hygienic environments, while Duplex plates provide high strength and durability for offshore and petrochemical use.
Coils
Stainless steel coils are used in automated production lines. They can be stamped, laser cut, or formed into various components. 304 coils are used for general needs, 316L coils in marine conditions, and 904L coils in chemical processing.
Finishes and Sizes
Surface finishes matter. 2B is matte for industrial use, No.1 is rough from hot rolling, No.4 is brushed for visible use, BA and Mirror are glossy for clean or decorative use.
Common thicknesses range from 0.3 mm to 50 mm.Widths go up to 2000 mm, with standard tolerances for industrial fitting.
Comparison Table – 304 vs 316 vs 904L vs Duplex
Here’s a quick comparison of key features across 304, 316, 904L, and Duplex 2205 grades.
| Feature/Grade | 304 | 316 | 904L | Duplex 2205 |
| Chromium (%) | ~18 | ~16–18 | ~19–23 | ~22 |
| Nickel (%) | ~8 | ~10–14 | ~23–28 | ~5 |
| Molybdenum (%) | – | ~2.5 | ~4–5 | ~3 |
| Strength (Yield MPa) | ~205 | ~290 | ~220 | ~500+ |
| Corrosion Resistance | Moderate | High | Very High | Very High |
| Cost | Low | Medium | High | Medium-High |
| Sheets/Plates/Coils | ✓ | ✓ | ✓ | ✓ |
Choosing the Right Grade for Your Product & Industry
304 sheets and plates work well for food and beverage equipment due to easy cleaning and good corrosion resistance. 316 coils and plates are better for marine and coastal projects where salt exposure is high. Stainless steel 904L is ideal for chemical and fertiliser plants that deal with strong acids. For offshore rigs and desalination Duplex plates and coils offer both strength and durability. Always match the grade to the environment, strength needs and budget.
Quality Standards & Certifications
Stainless steel items have to meet with industry-tested standards to deliver consistency and dependability. Widely used specifications include ASTM A240, A312 and A213 which cover sheets, plates, and coils applied in industrial systems. Reputable suppliers are also ISO 9001:2015 certified for quality control. Critical documents such as Mill Test Certificates (MTCs) attest to the material’s chemical and mechanical characteristics. Approvals by agencies like TUV and SGS ensure conformity to safety and performance standards. Heat number traceability is also important, enabling the material to be traced back to production batch for complete documentation and inspection.
Conclusion
Every stainless steel grade has a specific role. Using the right one ensures better performance, long service life, and fewer maintenance issues. Whether you need corrosion resistance, strength or both, selecting the right form sheet, plate, or coil is just as important as the grade. For reliable sourcing, Nandini Steel supplies certified stainless steel products with competitive pricing and full technical support, helping industries make informed and cost-effective choices.
