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Stainless steel chemical composition depends on the grade and applicable product specification. Iron forms the base, chromium is the defining alloying element, and nickel, molybdenum, carbon and other elements vary between grades. There is no single recipe for every stainless steel.
For a 304 or 316 foil order, distinguish a published grade reference from the chemistry of the material actually offered. The table below compares one producer’s published strip-product limits. A purchasing decision should also identify the agreed specification, its edition and the applicable material report.
Stainless steel is an iron-based metallic alloy, rather than a pure element. The worldstainless introduction describes stainless steels with at least 10.5% chromium and no more than 1.2% carbon by mass. These are family-definition boundaries, not the complete requirements for a particular grade.
Different stainless families use different alloying systems. Austenitic 304 and 316 are important examples, but stainless steel also includes ferritic, martensitic and duplex families. Nickel and molybdenum are not mandatory additions in every stainless grade. The stainless steel grades guide provides the wider classification context.
Each element has a role, but its effect depends on the rest of the alloy and the processing conditions. SSINA’s alloying-elements guide explains the main contributions; the table summarizes those roles rather than promising a particular performance level.
| Element | Main significance when reading a composition sheet |
|---|---|
| Iron, Fe | Base metal; commonly listed as the balance |
| Chromium, Cr | Supports formation of the passive surface associated with corrosion resistance |
| Nickel, Ni | Helps stabilize austenite and contributes to toughness and ductility in relevant grades |
| Molybdenum, Mo | Supports resistance to localized corrosion in relevant alloy systems and environments |
| Carbon, C | Controlled by grade; low-carbon variants help address sensitization associated with welding heat |
| Nitrogen, N | Can contribute to strength and corrosion resistance in specified austenitic and duplex grades |
| Manganese and silicon, Mn/Si | Have grade-dependent metallurgical roles, including deoxidation or oxidation resistance |
| Phosphorus and sulfur, P/S | Read their specified limits; an intentional addition in one grade is not a universal target for another |
Sulfur illustrates why grade-specific interpretation matters. Use the specified grade’s requirements when considering a substitution.
These are published producer limits, rather than Myriad heat-analysis results. Use the agreed product specification and applicable material report for order acceptance.
| Element | 304 / UNS S30400 | 316 / UNS S31600 |
|---|---|---|
| Chromium, Cr | 17.5–19.5 | 16.0–18.0 |
| Nickel, Ni | 8.0–10.5 | 10.0–14.0 |
| Molybdenum, Mo | Not listed in the cited table | 2.00–3.00 |
| Carbon, C | 0.07 max | 0.08 max |
| Manganese, Mn | 2.00 max | 2.00 max |
| Silicon, Si | 0.75 max | 0.75 max |
| Nitrogen, N | 0.10 max | 0.10 max |
| Phosphorus, P | 0.045 max | 0.045 max |
| Sulfur, S | 0.030 max | 0.030 max |
| Iron, Fe | Balance | Balance |
“Max” means an upper limit, not a typical amount. A range identifies the listed lower and upper limits. “Balance” does not justify subtracting every other element’s maximum from 100% to produce one fixed iron content. The absence of a 304 molybdenum row in this source does not mean a zero-molybdenum requirement.
In the Myriad strip reference above, 304 contains 17.5–19.5% chromium and 8.0–10.5% nickel, with the other listed limits and iron as the balance. The familiar “18/8” description is shorthand, not a promise of exactly 18% chromium and 8% nickel in every heat. For product and testing context, see the 304 stainless steel coil guide.
The carbon limit must match the actual grade being ordered. The cited 304 reference lists 0.07% maximum carbon, while Myriad’s 304L strip data list 0.030% maximum. A low carbon result alone does not establish compliance with all requirements of a 304L product specification.
In the same producer’s strip reference, 316 lists 16.0–18.0% chromium, 10.0–14.0% nickel and 2.00–3.00% molybdenum, with carbon and other controlled elements as shown above. Molybdenum is an important distinction when comparing these references. It supports localized-corrosion resistance in relevant conditions, but does not make 316 suitable for every chloride or seawater exposure. The 304 vs. 316 comparison provides related selection context.
316L adds a low-carbon distinction that should remain visible on the order and report. Myriad 316L strip data list 0.030% maximum carbon. Lower carbon helps address sensitization risk associated with welding, while the actual fabrication and service requirements still need review. See the 316 vs. 316L guide for the grade comparison.
Online tables may use different product rules or reference conventions. For example, SSINA’s general composition table shows 304 chromium at 18–20% and carbon at 0.08% maximum, while the ATI strip table used here lists 17.5–19.5% and 0.07% maximum. SSINA also advises checking the specific product requirements. These values should not be combined into a new range and labeled as one verified standard.
The document’s purpose determines what its numbers can establish. A grade range, typical producer data, a historical summary and an actual analysis have different roles; one does not automatically replace another.
| Information type | What to check before using it |
|---|---|
| Product-specification limits | Exact specification, edition, grade/UNS, product form and applicable acceptance rules |
| Producer reference or typical data | Whether values are limits, ranges or typical values, and which products they describe |
| Historical measurement summary | Which samples and methods it summarizes; whether it applies to the material now offered |
| Heat analysis or product analysis | Identity and traceability, analysis basis, method where relevant, and comparison with the agreed requirements |
For flat-rolled purchasing, ASTM A240/A240M and the general requirements of ASTM A480/A480M are relevant specification references. Their applicability must match the product and order. A familiar grade designation or an EN/JIS cross-reference is not, by itself, proof that every requirement is interchangeable.
Start with the required grade and product specification, then compare the applicable analysis with those requirements. Identify the offered material and the report’s heat or batch references; clarify whether the result is heat analysis or a product-analysis check. ASTM A751 addresses steel chemical-analysis practices and states the priority of the applicable product specification. Use the applicable specification for product-analysis allowances and sampling rules.
The analytical method must be capable of checking the elements that matter. Thermo Fisher’s stainless-analysis guide explains that conventional handheld XRF does not measure carbon. An XRF alloy-identification result therefore cannot, on its own, establish the carbon requirement distinguishing 304 from 304L or 316 from 316L.
Specify a suitable carbon-capable method when carbon needs verification. ASTM E1019 provides an entry point for combustion and inert-gas-fusion methods for specified elements in relevant metals. The laboratory should confirm the appropriate method, sampling and specimen suitability for the foil and the required elements. An analysis of selected elements should not be described as verification of every chemical requirement.
Chemistry is one part of material qualification. Delivery condition, microstructure, surface, mechanical properties and service conditions require their own evidence. A composition table does not establish a coil’s temper, hardness, tensile strength or corrosion life.
Knowledge-base research illustrates this separation. Zhang Mingxian’s 2017 study, consulted through Myriad’s knowledge base, listed the chemistry of its experimental 316L/316LN materials separately from the sensitization and microstructure conditions it investigated. It is third-party research, not a Myriad test or a general qualification of commercial 316 foil. The study’s experimental chemistry and processing values are not used as this article’s grade-composition limits.
Steel is an alloy made primarily of iron and carbon. Typically, carbon makes up between 0.2% and 2.1% of the material’s weight. Other elements may be added to improve certain properties. For example, manganese helps with hardenability, and silicon can boost strength. Steel composition can vary significantly depending on the intended use and grade of the steel.
Steel is an alloy, or a combination of metals, predominantly made up of iron with small amounts of carbon. It’s known for its strength and durability, which make it a versatile material used in many industries, such as construction, transportation, and manufacturing.
Myriad supplies stainless steel foil and precision strip, with the requested grade, condition and dimensions reviewed for the order. Use the 304/304L foil and thin-sheet page or 316/316L foil and thin-sheet page for the relevant product inquiry. Width and edge requirements can also be reviewed through Myriad coil slitting.
Include the following with an RFQ or purchase order submitted for review:
Chemical-analysis requirements should be confirmed before the order is agreed. A report’s existence does not establish that it includes every requested element or a separate third-party chemical analysis. If material selection is still open, provide the relevant application conditions so the outstanding requirements can be discussed.
Smaller-quantity requests can be reviewed individually. Myriad’s standard minimum is 100 kg per specification item within one order, defined by the same grade, thickness, width and material condition; lower quantities require a separate application.
Submit the actual specification or PO for review so availability and the required documentation can be checked together.
The chemical structure of steel, like other metals and alloys, consists of a crystalline lattice. This lattice is formed by iron atoms, with carbon atoms occupying the interstitial spaces between them. The specific arrangement of these atoms and the presence of other elements can alter the steel’s properties.
The composition comparison uses ATI’s public strip-product Minimum/Maximum columns, checked on November 7, 2026. Only the standards’ publicly available scope statements were consulted; their complete chemistry tables and test procedures were not reviewed. No new chemical analysis was performed, and the displayed values are not a certificate for a Myriad heat or batch.
The knowledge-base reference is Zhang Mingxian, 316L(N)奥氏体不锈钢晶间腐蚀与晶界特征分布优化的研究 (2017), used only for the distinction between experimental chemistry and investigated processing or microstructure conditions. The technical article is a guide to reading and requesting composition information; actual acceptance follows the requirements agreed for the material.
