stainless steel materials

• Five Stainless Steel Families
• Austenitic Grades
• Ferritic Grades
• Martensitic Grades
• Duplex Grades
• PH Grades
• Family Comparison
• Standards by Product Form
• Corrosion Selection
• Temperature and Strength
• Fabrication
• Product Forms
• Quality Control
• Applications
• FAQs
• Request a Quote

Shaanxi Shangyou Stainless Steel Co., Ltd. supplies stainless steel materials for pressure equipment, chemical processing, food and pharmaceutical systems, marine and desalination projects, energy equipment, transport, architecture, machinery, precision components and industrial distribution. Each inquiry can be reviewed against the metallurgical family, grade/UNS designation, product standard, product form, dimensions, tolerance, condition, surface, fabrication drawing, inspection plan and final service environment.

Stainless steels are iron-based alloys whose chromium content enables formation of a protective passive film under suitable conditions. Their properties are not controlled by chromium alone. Nickel, molybdenum, nitrogen, manganese, carbon, titanium, niobium, copper and other elements influence phase balance, corrosion resistance, strength, hardenability, weldability and high-temperature behavior.

The five widely used purchasing families-austenitic, ferritic, martensitic, duplex and precipitation-hardening-describe metallurgical structure or strengthening route. These families help narrow selection, but they do not replace the exact UNS number and form-specific standard. A 316L plate, a TP316L pipe and a 316L casting are ordered under different specifications and may have different permitted chemistry, properties and inspection routes.

Austenitic stainless steels include most 200- and 300-series grades and many high-alloy corrosion- or heat-resistant grades. They are valued for formability, weldability and toughness. Annealed austenitic material is often weakly magnetic or effectively nonmagnetic, but cold work and welding can create magnetic response. Magnetism is therefore not a reliable acceptance test for grade identity.

Ferritic stainless steels are chromium-based and normally magnetic. Many contain little or no deliberate nickel, while stabilized grades use titanium and/or niobium to improve welding and intergranular-corrosion behavior. Ferritic grades can offer lower thermal expansion and good resistance to oxidation or stress-corrosion cracking in selected environments, but toughness and weldability depend on grade and section thickness.

Martensitic stainless steels are selected when hardness, strength or wear resistance is more important than the broad corrosion resistance of 304 or 316L. Final properties come from the complete heat-treatment route: annealing or softening for machining, austenitizing, quenching and tempering. A grade name without final hardness/condition is incomplete.

Duplex grades combine ferrite and austenite. Their high strength can reduce required section thickness under an approved design, while higher chromium, molybdenum and nitrogen grades can improve chloride resistance. They are not universally superior: welding, forming, temperature exposure, toughness, sour-service limits and phase balance must all be controlled.

PH stainless steels develop high strength through solution treatment followed by aging. The family includes martensitic and semi-austenitic types. The age condition-such as H900, H1025 or H1150 for applicable 17-4PH products-changes strength, hardness, toughness and environmental-cracking behavior, so it must appear on the order and MTC.

A family describes a broad metallurgical structure. A grade defines controlled chemistry and, through its product standard, required properties and supply condition. "Austenitic stainless" may refer to 201, 304L, 316L, 310S, 904L or many other grades with very different performance.

Wrought products commonly use UNS S- or N-series designations and ASTM A-product specifications. Cast grades use designations such as CF8M, CA6NM or duplex casting grades under casting specifications. Weld filler metals use AWS classifications. Similar nominal chemistry does not create automatic interchangeability between wrought base metal, casting and weld metal.

"304," UNS S30400 and EN 1.4301 identify closely related material concepts, but the exact product specifications control chemistry, dimensions, condition, testing and certification. Cross-reference tables are for navigation-not for unapproved substitution.

Cold work can transform some austenite to martensite. Welding produces a heat-affected zone and weld-metal structure. Quenching produces martensite in hardenable grades. Improper duplex thermal exposure can precipitate harmful intermetallic phases. Final condition must therefore be verified after significant processing.

The passive film needs suitable chemistry and surface condition. Chlorides, reducing acids, oxidizing contaminants, crevices, deposits, temperature and tensile stress can produce pitting, crevice corrosion, general corrosion or stress-corrosion cracking. Grade selection must use actual operating and cleaning conditions.

201 and 202 use manganese and nitrogen to replace part of the nickel used in conventional 300-series grades. They remain austenitic under the specified condition but can work harden rapidly and become magnetic after forming. They should be chosen on their own chemistry, corrosion data, formability and standard-not as unnamed "low-nickel 304."

304 is the broad general-purpose reference, while 304L controls carbon for welded fabrication and sensitization resistance. Where code strength at temperature matters, 304, 304L, dual-certified material and H grades have distinct rules. A dual certification should be based on actual chemistry, properties and product-standard requirements rather than a sales label.

Molybdenum improves localized-corrosion resistance compared with 304 in many environments. It does not guarantee immunity in warm chlorides, stagnant seawater, tight crevices, aggressive cleaning chemicals or high tensile stress. Hygienic performance also depends on roughness, weld quality, drainage and cleaning validation.

Titanium or niobium stabilization helps control chromium-carbide-related sensitization in specified thermal and welding conditions. Grade choice should consider operating temperature, time, forming, weld procedure, stabilization heat treatment and code allowables. A stabilized grade is not simply a higher-priced version of 304L.

309S, 310S and H-grade variants are chosen for different oxidation, carburization, creep and thermal-cycle conditions. Maximum service temperature cannot be stated without the atmosphere, load, section, time and acceptable scale loss. Sulfidizing, reducing, halogen or molten-salt environments may change the grade ranking.

904L and S31254 extend resistance in selected acid/chloride environments through higher nickel, molybdenum, nitrogen and/or copper. They also increase material cost, welding/filler considerations and product-form constraints. Compare them with duplex or nickel-alloy options from the actual corrosion and design basis.

• Annealed austenitic stainless steel cannot normally be strengthened by conventional quench-and-temper heat treatment; cold work is a major strengthening route.
• Cold work increases strength and magnetic response but reduces ductility and can affect environmental cracking.
• 304L and 316L control carbon, but the "L" does not mean low strength, low alloy or universal post-weld immunity.
• Austenitic grades generally retain good low-temperature toughness, but code exemption and impact testing remain product- and design-specific.
• Weld-metal ferrite can be deliberately controlled to reduce hot cracking; a magnetic weld does not automatically indicate the wrong base grade.

409L is designed around oxidation, exhaust and cost requirements rather than a bright architectural surface. 430 provides improved appearance and general corrosion resistance for mild indoor or atmospheric use. These grades should not be sold using 304/316 corrosion expectations.

439, 441 and 444 use titanium and/or niobium stabilization to improve resistance to intergranular attack and weld-related property loss. Stabilization does not remove every welding constraint. Heat input, grain growth, shielding, joint design and thickness remain important.

444 can be considered for hot-water and selected chloride-bearing equipment because molybdenum improves localized-corrosion resistance. It offers different forming, welding, toughness and availability characteristics from 316L. Service data-not a single pitting index-should determine substitution.

High-chromium grades can provide oxidation and scaling resistance in selected high-temperature atmospheres. They may have limited ductility and notch toughness and can form embrittling phases during inappropriate thermal exposure. Fabrication sequences should be qualified before production.

• Ferritic stainless steels are normally magnetic; magnetism does not identify a specific ferritic grade.
• They are not conventionally hardened by austenitizing and quenching like martensitic grades.
• Lower thermal expansion can benefit exhaust and heat-exchanger design, but modulus, thermal conductivity and fatigue still require calculation.
• Grain coarsening in the weld/HAZ can reduce toughness, particularly in thicker sections or unstabilized grades.
• Ferritic stainless steels can be susceptible to embrittlement after exposure in certain intermediate-temperature ranges; temperature/time limits are grade-specific.
• Surface ridging/roping and anisotropy may control visible formed parts.

410 is the general martensitic reference for moderate corrosion resistance with heat-treatable strength. 403 is used under more specialized turbine/compressor specifications. Neither grade should be ordered solely by a target hardness without the material standard, section size, heat-treatment route and toughness requirement.

420-type products can vary in carbon and therefore in attainable hardness. The order should identify UNS or standard grade, annealed supply condition, final hardening/tempering, hardness range, distortion allowance, grinding stock and surface integrity. "Food grade" or "surgical grade" is not a material specification.

431 and S41500 use nickel and controlled chemistry to balance strength, toughness and corrosion for shafts, valves, hydro equipment and other components. Their welding and heat treatment differ from plain 410. For pressure or rotating parts, specify impact/toughness, NDE and test-coupon orientation.

440A, 440B and 440C are not interchangeable. Higher carbon supports higher hardness and wear resistance but also increases carbide content and can reduce toughness and corrosion performance. Carbide distribution, retained austenite, quench route, cryogenic processing if used, temper and final grinding can affect performance.

• Final properties depend on austenitizing, quenching and tempering; the supplied annealed condition is not the final service condition.
• Hardness alone does not define toughness, fatigue strength, carbide distribution or corrosion resistance.
• Welding can create a hard brittle HAZ. Preheat, controlled hydrogen, filler selection and post-weld heat treatment may be required.
• Tempering temperature changes strength, toughness and corrosion behavior; use the approved heat-treatment procedure.
• Martensitic grades are generally magnetic in service condition, but magnetic testing cannot distinguish grade or temper.
• Grinding burn, decarburization and retained tensile stress can reduce fatigue or corrosion performance.

Lean duplex grades reduce nickel and/or molybdenum relative to 2205 while using chromium, manganese and nitrogen to retain useful strength and corrosion resistance. They can compete with 304L/316L in selected service, but they should not inherit 2205 or 2507 corrosion claims.

2205 is the most widely specified duplex family. UNS S31803 is an older broad chemistry range; S32205 narrows key elements to support performance. Material may meet both, but "dual-certified" should appear only when chemistry, heat treatment and properties satisfy both ordered specifications.

S32750 and S32760 contain higher chromium, molybdenum and nitrogen than 2205 and are considered for severe chloride systems. They are separate grades, not two names for one chemistry. Welding consumables, interpass temperature, heat input, ferrite/austenite balance, crevice geometry and service temperature require engineering control.

The target structure contains both ferrite and austenite, but no universal 50/50 acceptance applies to every grade, form, weld or code. Excessive ferrite can reduce toughness/corrosion, while excessive austenite can reduce strength. Sigma, chi, nitrides and other detrimental phases can form through improper heat treatment or thermal exposure.

• Duplex strength is higher than common austenitic grades, but thickness reduction requires design-code calculation and fabrication review.
• Improved chloride SCC resistance is not immunity to SCC, hydrogen cracking or sulfide stress cracking.
• Prolonged elevated-temperature exposure can embrittle duplex grades; do not use a room-temperature corrosion ranking as a high-temperature design basis.
• Solution annealing and rapid cooling establish the required structure for wrought products; local heating and slow cooling can damage it.
• Welding must control heat input, interpass temperature, filler composition, shielding/purge and joint geometry.
• ASTM A923/A1084 or project corrosion/metallographic tests require a stated method, acceptance criterion and sampling plan; passing a test does not prove unlimited service life.

17-4PH is widely supplied as plate/sheet, bar, forging and casting under different standards. Solution-treated Condition A provides a starting structure for machining or later aging, but it is not interchangeable with H900, H1025, H1150 or another aged condition. Lower-temperature aging commonly gives higher strength, while higher-temperature aging generally trades strength for toughness and dimensional/environmental behavior. Use the exact product-standard property table.

15-5PH is a separate UNS grade with its own chemistry and product availability. It is often selected for forged or machined components where directional toughness and high strength are important. It should not be described as "improved 17-4PH" without the actual design requirement and material specification.

17-7PH is commonly used in sheet, strip and wire for springs, diaphragms, clips and formed parts. It can be supplied and processed through Condition A and transformation/aging routes such as TH, RH or CH conditions when covered by the specification. Forming before transformation, dimensional change and final heat treatment must be planned together.

S13800 is used for demanding high-strength components where cleanliness, toughness and stress-corrosion performance under a defined condition are important. The required melting practice, specification, condition and test program should be included in the RFQ; a generic commercial grade name is insufficient.

• The age condition is part of the material specification and must appear on the purchase order, certificate and part drawing.
• A hardness reading cannot prove the complete heat-treatment sequence, toughness, grain structure or corrosion behavior.
• Machining in Condition A followed by aging can support dimensional control, but distortion and growth must be allowed for.
• Welding should be qualified around the base condition, filler, heat input and final aging route. Weld metal may not precipitation harden like the base metal.
• High-strength conditions require special review for hydrogen embrittlement, stress-corrosion cracking, plating/pickling and sour service.

Family comparison is a screening tool. The correct material is the one that meets corrosion, pressure, temperature, strength, fabrication, hygiene, code, availability and lifecycle requirements together. A high-alloy grade may be unnecessary for a mild environment; a cheaper grade may be costly if it forces redesign, coating, frequent replacement or difficult fabrication.

• L grades: control carbon to reduce sensitization risk in welded or thermally exposed fabrication. They are not necessarily lower strength in every product specification.
• H grades: use carbon and often grain-size requirements to support creep/stress-rupture performance at elevated temperature. They are not intended as a universal corrosion upgrade.
• Ti/Nb stabilized grades: use titanium or niobium to bind carbon under specified conditions. Stabilization treatment and service temperature still matter.
• N grades or nitrogen-alloyed grades: nitrogen can raise strength and pitting resistance and helps control duplex phase balance. The exact specification controls limits.

Common dual certifications-such as 304/304L, 316/316L or S31803/S32205-are acceptable only when the heat chemistry, mechanical properties, heat treatment and form-specific standard satisfy both ordered grades. A certificate should state the actual specifications and results; a product label alone is not enough.

• Use the exact designation and edition required by the contract or construction code. "Latest edition" can conflict with a frozen project basis.
• ASTM A240 controls flat products; it cannot be transferred automatically to pipe, tube, bar, wire, fittings or forgings.
• ASTM and ASME specifications may be technically related, but ASTM compliance alone does not establish ASME Code acceptability or allowable stress.
• Product prefixes such as TP, WP and F belong to specific standards and should not be mixed across forms.
• Some historical stainless standards have been withdrawn. Do not reuse an old designation without confirming project acceptance and a current replacement route.

Chromium, molybdenum and nitrogen generally improve resistance to chloride pitting, but a calculated PREN value is only a chemistry-screening indicator. It does not include surface, heat treatment, inclusions, weld condition, crevice geometry, chlorination, deposits or actual temperature. Do not publish a universal "PREN ranking" as an operating limit.

Chromium carbide or nitride precipitation can reduce local chromium near grain boundaries. Low-carbon grades, stabilization and correct solution annealing help control susceptibility, but the relevant test depends on family and grade. ASTM A262 applies to selected austenitic materials; ASTM A763 applies to selected ferritic materials. Test practice and acceptance must be ordered explicitly.

Common austenitic grades can be susceptible to chloride SCC when temperature, chloride, stress and oxygen/potential combine. Ferritic and duplex structures can improve resistance in selected conditions, but they introduce toughness, welding and hydrogen-related boundaries. High-strength martensitic and PH conditions need special SCC/hydrogen review.

ANSI/NACE MR0175/ISO 15156 applies to defined H2S-containing oil and gas production environments and material conditions. It is not a general certificate of corrosion resistance. Exact grade, product form, condition, hardness, cold work, temperature, H2S partial pressure, chloride and pH limits must be checked. The standard focuses on cracking within its scope, not all general or localized corrosion.

These are qualitative family trends, not design values. Use the exact grade, product standard, section size, condition, temperature and test certificate for calculations.

Austenitic 304 or 316 can become magnetic after cold working, while annealed products may show low response. Weld metal can contain ferrite. Ferritic, martensitic, duplex and common PH grades are generally magnetic. A magnet cannot verify molybdenum content, carbon level, UNS number, heat treatment or code compliance.

Austenitic grades are often preferred for cryogenic service because their FCC structure maintains toughness, but product standard, thickness, weld metal and design-code impact rules still apply. Ferritic, martensitic and duplex materials show temperature-dependent toughness and require a defined minimum design metal temperature and impact-test basis.

Oxidation resistance and load-bearing creep strength are separate. 310S may form a protective scale in a suitable atmosphere but does not automatically carry pressure at the same temperature. H grades, stabilized grades and ferritic heat-resistant grades have distinct property bases. Use time-dependent allowable stresses, atmosphere, thermal cycling and fabrication condition.

Flat product weight (kg) = Thickness (mm) x Width (m) x Length (m) x Density (g/cm3)

Round bar weight (kg) = 0.0007854 x Diameter² (mm) x Length (m) x Density (g/cm3)

Pipe/tube weight (kg/m) = 0.0031416 x Wall (mm) x [OD (mm) - Wall (mm)] x Density (g/cm3)

Use the exact alloy density and ordered dimensional tolerances. A universal 7.93 or 8.00 factor can create errors for ferritic, martensitic, duplex and PH materials.

Solution annealing dissolves chromium carbides and other phases under the alloy/product specification, followed by cooling fast enough to retain the required structure. Local stress relief at a lower temperature does not necessarily restore corrosion resistance. Post-fabrication solution treatment can distort equipment and create scale, so the design and welding route should account for the final condition.

Ferritic annealing temperatures and cooling practices are grade-specific. Stabilized chemistry reduces some risks but does not prevent grain growth or every embrittlement mechanism. Heavy forming or welding may require additional qualification rather than a generic "anneal after fabrication" note.

Section size, furnace uniformity, austenitizing temperature, hold time, quench severity, retained austenite and temper determine final properties. Multiple tempering, cryogenic treatment or subzero cooling may be used in specialized applications only when specified. Hardness should be measured in the final service condition and at agreed locations.

Duplex grades need sufficient solution treatment and rapid cooling to avoid sigma/chi/nitrides and restore phase balance. Welded fabrications are often used as welded under qualified procedures rather than fully solution annealed, but heavy forming or repair may require project-specific treatment. Never apply a carbon-steel PWHT cycle by analogy.

PH properties come from the exact solution/aging sequence. A lower aging temperature is not simply "better" because it raises strength; toughness, corrosion/SCC resistance and dimensional stability can change. The component specification must state who performs final aging and which party certifies final properties.

Saw, shear, laser, plasma, waterjet and abrasive processes may be selected according to form, grade, thickness, edge requirement and downstream treatment. Thermal cutting creates a heat-affected edge that may need removal for fatigue, corrosion, forming or precision machining. Use clean abrasives and prevent embedded carbon steel.

Austenitic grades work harden; rubbing tools and interrupted light feeds can harden the surface ahead of the cut. Forming can induce martensite and magnetic response. Welding requires clean joints, suitable filler, controlled heat input and backside shielding where root oxidation affects corrosion/hygiene.

Ferritic sheet can form well, but bend direction, surface ridging and lower ductility than common austenitic grades must be considered. Welding thick or unstabilized material can cause grain coarsening and toughness loss. Filler and heat treatment should follow the grade/product application.

Machine and form martensitic grades in an annealed or approved soft condition when possible. Welding requires an engineered sequence including preheat, interpass, hydrogen control and post-weld treatment where needed. Final grinding should avoid burn and tensile residual stress.

Higher strength means higher forming loads and springback. Welding should use approved filler, joint geometry, heat input/interpass limits and shielding/purge to achieve phase balance and corrosion performance. Autogenous welds and repeated repair cycles need special review.

Processing usually coordinates solution condition, machining/forming and final aging. Some operations can alter the transformation needed for semi-austenitic PH grades. Welding and post-weld aging should be qualified; the weld may not reach base-metal strength.

ASTM A380/A380M provides practices for cleaning, descaling, pickling and passivation of stainless systems, while ASTM A967/A967M covers chemical passivation treatments for parts. These processes are not interchangeable. Specify surface condition, contamination removal, chemical method, rinse-water quality, acceptance test and protection after treatment.

Surface finish can improve cleanability or remove fabrication contamination, but polishing alone does not upgrade the base alloy. Roughness, lay direction, weld blending, crevices, heat tint and cleaning chemistry all influence service performance.

Do not publish one thickness, diameter or width range for all stainless families. Availability depends on grade, melting route, form, standard, condition, mill route, tolerance, test scope and quantity. A broad "0.1-500 mm" statement can be technically misleading when a specific grade/condition is available only in limited forms.

1. Review the purchase order, drawing, family/grade, product specification, design code and service notes.
2. Confirm heat/lot identity, manufacturing route, supplied condition and required final heat treatment.
3. Review original mill documentation for chemistry, mechanical properties and specification-required tests.
4. Inspect dimensions, geometry, surface, edges/ends and marking against the order.
5. Perform ordered PMI, NDE, pressure, corrosion or metallurgical testing under defined methods and acceptance criteria.
6. Transfer traceability through cutting, slitting, machining, heat treatment and repacking.
7. Review all reports, markings, packing list and release status before shipment.

PMI chemistry can help separate 304 from 316 or verify Cr/Ni/Mo, but it does not prove austenitic/ferritic phase balance, solution annealing, martensitic temper, PH aging, toughness or corrosion-test performance. XRF cannot verify the low carbon that distinguishes 304L/316L or the nitrogen that is important in duplex grades. Use MTC review plus the correct analytical/metallurgical method.

Heat/lot identity should be transferred to remnants and cut pieces by an approved traveler, stencil, low-stress stamp, tag, map or package-level system. The marking method must not damage the service surface. If mixed heats are allowed, packing and documents should keep them distinguishable.

304/304L and 316/316L are used in tanks, food and beverage equipment, pharmaceutical systems, process piping, heat exchangers, architecture, transport and general fabrication. 321/347 support selected elevated-temperature and welded service. 310S addresses specific furnace atmospheres, while 904L/S31254 serve more aggressive chemical/chloride conditions under qualified design.

409L, 439 and 441 are common in exhaust, heat shields and thermal systems. 430 is used in appliances, interior trim and kitchen equipment. 444 can be selected for hot-water tanks and heat exchangers. Product thickness, surface appearance, welding and actual chloride temperature remain important.

410, 420, 431, 440C and related grades are used for shafts, valve components, turbine/compressor parts, cutlery, molds, fasteners, bearings and wear components. Final heat treatment, hardness/toughness balance, surface grinding and corrosion environment determine life.

Lean duplex, 2205 and super duplex grades are used in tanks, pressure vessels, pulp and paper equipment, chemical systems, oil and gas, offshore equipment, heat exchangers, desalination and seawater systems. Selection requires phase-controlled fabrication, code approval and evaluation of chloride, temperature, crevices and H2S conditions.

17-4PH, 15-5PH, 17-7PH and 13-8 Mo are used for high-strength shafts, fasteners, valve components, springs, diaphragms, molds, aerospace-related and precision parts. The final aged condition and inspection specification are inseparable from the application.

Labels such as "food grade," "marine grade," "surgical grade," "nuclear grade" or "aerospace grade" are not complete material specifications. Each industry can impose additional requirements for cleanliness, melting route, residual elements, surface finish, validation, approved sources, NDE, traceability and design code.

Packing materials should be clean, dry and compatible with stainless steel. Avoid carbon-steel contact that can embed iron and avoid chloride- or sulfur-bearing packing/markers on critical surfaces. State transport mode, storage duration, destination climate, package limits, lifting method and required piece/bundle markings.

The inquiry can be screened first by stainless family and service, then narrowed to a grade/UNS, product standard, condition and form. This avoids selecting 304, 316L, 430, 2205 or 17-4PH only because the name is familiar.

A project may combine plate, pipe, tube, bar, profiles, fittings and forgings. Each form can require a different ASTM/ASME/EN specification while retaining the intended alloy identity and compatible condition. A consolidated bill-of-material review helps expose mismatched prefixes, standards or heat treatments.

Cutting, slitting, leveling, drilling, beveling, machining, polishing and other approved processing can be evaluated against the family, supplied condition, final tolerance and traceability plan. The quotation can distinguish raw-material acceptance from finished-part acceptance.

EN 10204 3.1 MTC, heat/lot traceability, PMI and optional project-specific inspection can be incorporated when stated in the RFQ. Family-specific corrosion, hardness, impact, phase or NDE requirements should be agreed with exact methods and acceptance criteria before production.

Packing can be planned around product form, surface, transport route and unloading method. Polished sheets, strip edges, tube bores, machined faces and long bars require different protection.

Send These Details for an Accurate Quotation

Copy-and-Send RFQ Template

"Duplex stainless steel UNS S32205 seamless pipe to ASTM A790/A790M, project-approved edition; NPS/schedule and cut lengths attached; solution-annealed condition per specification; plain beveled ends to project drawing; chemistry/mechanical review, required hydro/NDE, PMI, ordered ASTM A923 method/acceptance and EN 10204 3.1 MTC; heat traceability; export packing. Service chemistry, design pressure/temperature and code basis attached."

This example demonstrates information structure only and does not establish availability or material suitability.