| 304 / 304L | S30400 / S30403 | 1.4301 / 1.4307 | Austenitic | Approximately 18% Cr / 8% Ni | Good general corrosion resistance, excellent formability and weldability; 304L offers lower carbon for improved weld-zone corrosion resistance. | Food-processing equipment, architectural components, chemical vessels, pumps, valves and general machinery. | ASTM A182 / ASME SA182; ASTM A351 / ASME SA351 where cast-equivalent specifications are required. | Solution annealing is commonly used after forging; avoid prolonged exposure to sensitization temperatures during fabrication. |
| 316 / 316L | S31600 / S31603 | 1.4401 / 1.4404 | Austenitic | Approximately 16–18% Cr / 10–14% Ni; 2–3% Mo | Better resistance to chlorides and many process chemicals than 304; 316L supports welded fabrication. | Marine hardware, pharmaceutical equipment, chemical processing, coastal infrastructure, heat exchangers and hygienic systems. | ASTM A182 / ASME SA182; EN 10222-5 for pressure-purpose forgings. | Solution annealing and rapid cooling are normally specified to restore corrosion resistance after hot forging. |
| 321 | S32100 | 1.4541 | Stabilized Austenitic | Approximately 17–19% Cr / 9–12% Ni; titanium stabilized | Good resistance to intergranular corrosion after welding and suitable for elevated-temperature service. | Exhaust manifolds, thermal-processing equipment, expansion joints, aerospace components and high-temperature piping. | ASTM A182 / ASME SA182; EN 10222-5. | Control forging temperature and heat treatment to maintain a stable microstructure and prevent excessive grain growth. |
| 347 | S34700 | 1.4550 | Stabilized Austenitic | Approximately 17–20% Cr / 9–13% Ni; niobium stabilized | Strong resistance to sensitization and good performance during repeated high-temperature exposure. | Power-generation piping, refinery equipment, high-temperature headers and aircraft-engine components. | ASTM A182 / ASME SA182; EN 10222-5. | Requires controlled solution treatment; forging practice should limit overheating and excessive deformation in the final passes. |
| 410 | S41000 | 1.4006 | Martensitic | Approximately 11.5–13.5% Cr / minimal Ni | Heat treatable, high strength and moderate corrosion resistance; magnetic in service. | Pump shafts, valve components, fasteners, turbine parts and petroleum-industry hardware. | ASTM A182 / ASME SA182; ASTM A276 for bar-based component requirements. | Preheating, controlled cooling and tempering are important for limiting cracking and achieving the required mechanical properties. |
| 420 | S42000 | 1.4021 | Martensitic | Approximately 12–14% Cr / minimal Ni | Higher hardness and wear resistance than 410, with lower corrosion resistance than austenitic grades. | Cutting tools, surgical instruments, wear-resistant parts, shafts and high-strength valve components. | ASTM A182 / ASME SA182; ASTM A276 for general wrought product requirements. | Final hardness depends strongly on quenching and tempering; dimensional distortion should be considered during heat treatment. |
| 17-4 PH | S17400 | 1.4542 | Precipitation-Hardening Martensitic | Approximately 15–17.5% Cr / 3–5% Ni; copper-bearing | High strength, good toughness and useful corrosion resistance with multiple aging conditions. | Aerospace fittings, pump and valve bodies, marine components, high-strength shafts and petrochemical equipment. | ASTM A564; ASTM A705 / ASME SA705 for age-hardening stainless steel forgings. | Solution treatment and precipitation aging must match the specified condition, such as H900 or H1150, to balance strength and toughness. |
| Duplex 2205 | S31803 / S32205 | 1.4462 | Duplex Ferritic-Austenitic | Approximately 21–23% Cr / 4.5–6.5% Ni; 2.5–3.5% Mo | High strength, strong chloride-stress-corrosion resistance and better pitting resistance than 316L. | Offshore platforms, desalination equipment, chemical processing, pulp and paper systems, and pressure piping. | ASTM A182 / ASME SA182; ASTM A1049 for duplex stainless steel forgings and fittings. | Solution annealing and rapid cooling are essential; avoid prolonged temperatures that can form brittle intermetallic phases. |
| Super Duplex 2507 | S32750 | 1.4410 | Super Duplex Ferritic-Austenitic | Approximately 24–26% Cr / 6–8% Ni; 3–5% Mo; nitrogen alloyed | Very high pitting and crevice-corrosion resistance, high yield strength and strong chloride performance. | Seawater systems, offshore oil and gas equipment, chemical tankers, desalination plants and high-chloride process piping. | ASTM A182 / ASME SA182; ASTM A1049 for duplex and super-duplex forgings. | Strict control of forging temperature, phase balance and solution treatment is required to prevent secondary-phase precipitation. |