Stainless Steel grades

Martensitic precipitation-hardening stainless steel. Similar to 17-4PH but with better transverse ductility and toughness due to lower delta ferrite. Used for aerospace structural components, nuclear reactor parts, food processing equipment, and high-performance fasteners.

The most widely used precipitation-hardening stainless steel. Combines high strength (up to 1310 MPa UTS) with corrosion resistance comparable to 304. Delivered solution-annealed and hardened by simple low-temperature aging. Used in aerospace, medical, oil & gas, and nuclear applications.

Super-austenitic stainless steel with 6% Mo. PREN >40 for outstanding pitting and crevice corrosion resistance. Bridges the gap between standard austenitics and nickel alloys. Used in seawater systems, flue gas desulfurization, bleach plants, and offshore.

Austenitic stainless steel with the highest work-hardening rate of all 300-series grades. Lower Cr and Ni (17/7 vs 18/9 for 304) makes it metastable — cold working induces martensite transformation for extreme strength (UTS >1300 MPa in full-hard temper). THE stainless spring steel. Used for stainless springs, washers, clips, structural components requiring high strength + corrosion resistance, and railway car bodies.

Higher-carbon variant of 304 (C max 0.15% vs 0.08%). The original "18-8" stainless steel. Higher C gives better strength after cold work but makes it susceptible to intergranular corrosion after welding. Largely superseded by 304/304L but still specified for springs and high-strength cold-worked applications. Used for springs, screen cloth, architectural trim, and wire forms.

Free-machining austenitic stainless steel — the most machinable of all austenitic grades. 0.15-0.35% S (as MnS inclusions) provides excellent chip-breaking. Trade-off: lower corrosion resistance than 304, poor weldability (hot cracking risk), and not suitable for cold forming. Used for high-volume automatic lathe parts: fittings, valves, screws, shafts, and precision components.

The world's most widely used stainless steel — the original 18/8 austenitic. Good corrosion resistance in atmospheric, organic, and inorganic environments. Excellent formability and weldability. Not recommended for chloride-rich or marine environments (use 316L). Used in food processing, kitchen equipment, architecture, tanks, and general engineering.

The most widely used austenitic stainless steel. Excellent corrosion resistance, good formability and weldability. Standard choice for food processing, chemical, and architectural applications.

Low-carbon version of 304. Maximum 0.030% C prevents sensitization during welding — no post-weld heat treatment needed. The standard choice for welded structures in food, chemical, and pharmaceutical industries. Often dual-certified with 1.4301.

Nitrogen-enhanced low-carbon 304. The N addition (0.12-0.22%) increases yield strength ~40% over 304L without reducing corrosion resistance or weldability. Used for pressure vessels, storage tanks, and cryogenic applications where higher design stress is needed.

High-chromium austenitic stainless for high-temperature service. Better oxidation resistance than 304 due to higher Cr (22-24%) and Ni (12-14%). Maximum service temperature ~1000°C (intermittent). Used for furnace parts, heat exchangers, fluidized bed combustors, kiln liners, and boiler baffles.

High-chromium, high-nickel austenitic for the highest service temperatures among standard austenitics. Oxidation resistance to ~1100°C (continuous). Higher Cr/Ni than 309S. Used for furnace parts, radiant tubes, heat treatment baskets, kiln liners, and high-temperature flue gas equipment.

Standard-carbon austenitic stainless steel with molybdenum. Higher C than 316L (max 0.07% vs 0.03%) giving slightly higher strength. Same corrosion resistance as 316L. Used where welding is not required or post-weld solution annealing is possible.

Low-carbon austenitic stainless steel with molybdenum addition. Superior corrosion resistance to 304, especially against chlorides and pitting. Standard choice for chemical processing, marine, medical implants, and pharmaceutical equipment.

Nitrogen-enhanced low-carbon version of 316. The N addition (0.12-0.22%) increases yield strength by ~30% over 316L without losing corrosion resistance or weldability. Used for pressure vessels, nuclear components, and structural applications requiring higher design stress.

Titanium-stabilized austenitic stainless steel with molybdenum. Stabilization prevents sensitization during prolonged high-temperature exposure. Very popular in Germany for chemical, pharmaceutical, and food processing. Being replaced internationally by 316L (1.4404) for most applications.

Low-carbon austenitic with 3-4% Mo — higher Mo than 316L (2-3%). Better pitting and crevice corrosion resistance (PREN ~30 vs ~25). Used in aggressive chemical environments where 316L is borderline: pharmaceutical, dye production, and organic acid processing.

Titanium-stabilized austenitic stainless steel. Similar to 304 but with Ti addition to prevent carbide precipitation during welding and high-temperature service (up to 800°C). Used for aircraft exhaust manifolds, boiler casings, jet engine parts, and chemical processing.

Niobium-stabilized austenitic stainless steel. Nb forms NbC instead of CrC, preventing sensitization during welding or high-temp service (425-860°C). Alternative to 321 (Ti-stabilized). Used for welded structures in chemical processing, aircraft exhaust systems, and high-temp piping.

Lowest-chromium ferritic stainless steel with Ti stabilization. Developed specifically for automotive exhaust systems as a cost-effective alternative to austenitic grades. Good oxidation resistance to ~800°C. Used for exhaust manifolds, catalytic converters, mufflers, and heat shields.

The basic martensitic stainless steel — 12% chromium with moderate carbon. Hardenable by heat treatment to provide good strength with moderate corrosion resistance. Used for steam turbine blades, pump shafts, valve components, bolts, and mining equipment.

Medium-carbon martensitic stainless steel. Higher hardness than 410 but lower than 420C (1.4034). Good balance of strength, corrosion resistance and machinability. Used for turbine blades, pump shafts, valves, bolts, surgical instruments, and cutlery.

High-carbon martensitic stainless steel. Higher hardness than 410 (up to 56 HRC). The standard knife steel for European cutlery. Used for kitchen knives, pocket knives, surgical scalpels, machine blades, roller bearings, and valve components. Not weldable.

Ferritic chromium stainless steel with good corrosion resistance and formability. Lower cost than austenitic grades. Used for automotive trim, kitchen sinks, architectural panels, and appliance components.