SS 304 — Stainless Steel (SS) Grade Specification, Properties & Equivalents

SS 304 stainless steel, often referred to as 18/8 stainless steel due to its austenitic chromium-nickel composition, is India's most widely used stainless steel grade. Its excellent corrosion resistance, formability, and weldability make SS 304 a workhorse across diverse industries, from architectural applications and kitchenware to chemical processing and food equipment manufacturing. Indian manufacturers and fabricators rely heavily on SS 304 for its balance of performance and cost-effectiveness, ensuring durability and hygiene in countless products. The availability of SS 304 in various forms like sheets, plates, bars, and tubes across major industrial hubs like Mumbai, Pune, and Chennai further solidifies its position as a preferred material for engineering and design solutions within India. Understanding the specific properties and sourcing options for SS 304 is crucial for making informed procurement decisions.

Chemical Composition of SS 304

SS 304 Chemical Composition (ASTM A240/A240M)

Mechanical Properties of SS 304

SS 304 Mechanical Properties (ASTM A240/A240M)

SS 304 Available Forms in India

Real-world Applications of SS 304

• Food Processing: Tanks, piping, chutes, and food-grade equipment due to hygienic properties.
• Kitchenware: Sinks, cookware, cutlery, and appliances requiring corrosion resistance.
• Chemical Processing: Tanks, reactors, and piping for handling various chemicals safely.
• Architectural: Decorative panels, handrails, and structural components in buildings.
• Automotive: Exhaust systems and trim components benefiting from heat and corrosion resistance.
• Medical: Surgical instruments and implants where biocompatibility and sterilization are key.
• Water Treatment: Storage tanks and piping for potable water systems.
• Heat Exchangers: Components requiring resistance to corrosive fluids at moderate temperatures.
• Fasteners: Bolts, nuts, screws, and washers for corrosive environments.

SS 304 Machinability & Weldability

Machining SS 304 requires careful consideration due to its work-hardening characteristics. Use sharp, high-speed steel or carbide tools with ample coolant to prevent overheating and excessive tool wear. Recommended cutting speeds are lower than those for carbon steels, typically ranging from 20-30 m/min for turning and 10-15 m/min for drilling. Employ heavy feeds to maintain a consistent chip load and break chips effectively, thereby minimizing heat buildup. Tools should have a positive rake angle and adequate clearance. For welding SS 304, it is considered readily weldable by all standard fusion and resistance methods, including TIG, MIG, and spot welding. Due to its low carbon content, intergranular corrosion after welding is generally not a concern if proper procedures are followed. However, to maintain maximum corrosion resistance in the heat-affected zone (HAZ), pre-cleaning is essential, and a post-weld passivation treatment is highly recommended. While filler metal is often not required for thin sections, using ER308L or similar low-carbon filler rods is common for thicker joints to ensure ductility and corrosion resistance. Post-weld heat treatment (PWHT) is typically not necessary for SS 304 in most applications, as it is usually used in the annealed condition.

SS 304 Heat Treatment & Processing

SS 304 stainless steel is primarily used in the annealed or cold-worked condition. Annealing of SS 304 is performed by heating the material to 1010-1120°C (1850-2050°F) followed by rapid cooling (water quench or air cool). This process restores ductility, refines grain structure, and maximizes corrosion resistance by dissolving chromium carbides. Full annealing provides the best properties for subsequent forming operations. SS 304 can be hardened significantly through cold working; however, it cannot be hardened by heat treatment as it is a non-hardenable austenitic steel. This means quenching from high temperatures does not produce martensite formation. Instead, the hardness and strength of SS 304 increase with increasing cold deformation. If cold working is employed, subsequent annealing may be required to regain ductility for further processing. Normalizing is not typically performed on SS 304 as it does not significantly alter the properties of the austenitic structure. Tempering is also not applicable to SS 304 in the conventional sense, as it is not hardened by quenching. Processing considerations for SS 304 should focus on maintaining its corrosion resistance, often through passivation after fabrication, especially in aggressive environments.

Sourcing SS 304 in India

SS 304 stainless steel is extensively manufactured and readily available from major Indian steel producers like Jindal Stainless, SAIL, and Posco Maharashtra, alongside numerous smaller mills and service centers. You can typically find SS 304 in stock across major industrial metros like Mumbai, Pune, Chennai, Delhi, and Ahmedabad. Minimum Order Quantities (MOQ) can vary significantly; for standard sheet and coil products, suppliers often cater to smaller orders, sometimes starting from 100 kg to 1 ton, while for specialized forms like bars or tubes, MOQs might be higher, potentially 500 kg to multiple tons depending on the size and specification. Pricing for SS 304 fluctuates based on global nickel and chrome prices, typically ranging from an indicative INR 280/kg to INR 350/kg, with tighter tolerances and specific finishes commanding premiums. Suppliers are expected to provide Mill Test Certificates (MTC) as per IS or ASTM standards, confirming the material

International Equivalents for SS 304

FAQs about SS 304