| Material designation | AISI/SAE 304L; UNS S30403; commonly specified under ASTM A240/A240M for plate, sheet, and strip. | Provides a recognized material identity for purchasing, fabrication, and traceability. | Request the material test certificate showing grade, heat number, applicable standard, and product form. |
| Nominal chromium content | Typically 18.0–20.0% by mass under ASTM A240 chemical limits. | Chromium forms a passive oxide film that provides the basic corrosion resistance of the stainless steel. | Verify the heat-analysis result against the agreed standard and purchase specification. |
| Nominal nickel content | Typically 8.0–12.0% by mass under ASTM A240 chemical limits. | Nickel helps stabilize the austenitic structure and supports ductility, formability, and toughness. | Check the certified chemical analysis rather than relying only on the grade label. |
| Maximum carbon content | 0.030% maximum by mass for the “L” low-carbon grade. | The lower carbon level reduces the risk of chromium-carbide precipitation during welding and helps preserve corrosion resistance near welds. | Confirm the carbon result and specify 304L when welding or post-weld corrosion performance is important. |
| Material structure | Austenitic stainless steel; generally non-magnetic in the annealed condition, although cold working can increase magnetic response. | Supports excellent formability and toughness for stamped, rolled, and fabricated coil components. | Request mill documentation for condition and avoid using magnetism alone as a grade-identification test. |
| Density | Approximately 7.9–8.0 g/cm³, depending on reference and composition. | Useful for estimating coil weight, freight requirements, slitting yield, and material consumption. | Compare the calculated mass with the ordered dimensions, theoretical weight, and actual weighbridge record. |
| Typical tensile strength | At least about 515 MPa for annealed sheet and strip under ASTM A240 requirements; actual values vary with product and condition. | Indicates resistance to tensile loading and helps determine forming and processing limits. | Review the certified tensile test results for each heat or lot as required by the purchase order. |
| Typical yield strength | At least about 205 MPa at 0.2% offset for annealed material under ASTM A240 requirements. | Important for calculating forming loads and assessing permanent deformation during service. | Check yield strength, tensile strength, and elongation together; do not evaluate quality from one value alone. |
| Elongation | Commonly specified at approximately 40% minimum in 50 mm for annealed ASTM A240 sheet and strip, subject to the applicable product specification. | High elongation supports deep drawing, bending, spinning, and other cold-forming operations. | Match the test method, gauge length, thickness range, and minimum value to the contract requirements. |
| Surface finish options | Common finishes include 2B, BA, No. 4, and No. 8, depending on the product and processing route. | Surface condition affects appearance, cleanability, friction, reflectivity, and suitability for architectural or food-processing equipment. | Define finish, roughness target where applicable, protective film, inspection lighting, and acceptable surface defects. |
| Common thickness range | Available thickness depends on the mill, standard, rolling route, and order quantity; thin-gauge and heavier coil products are both commercially available. | Thickness tolerance directly affects part dimensions, weight, forming behavior, and downstream slitting performance. | Confirm nominal thickness, permitted tolerance, measurement method, and sampling frequency before order placement. |
| Width and edge condition | Coils may be supplied in mill edge or slit edge configurations, subject to the ordered width and tolerance. | Accurate width and clean edges reduce trimming waste, tooling issues, burrs, and line stoppages. | Specify width tolerance, camber, flatness, edge condition, burr limit, and coil inside/outside diameter. |
| Weldability | Generally suitable for common fusion-welding processes when appropriate procedures and filler metals are used. | Low carbon content helps reduce sensitization risk compared with standard 304 during welding, although heat input and service conditions still matter. | Ask for welding recommendations, heat-treatment condition, and any intergranular-corrosion test requirement relevant to the application. |
| Corrosion-resistance scope | Good general resistance in many atmospheric, food, architectural, and mildly corrosive environments. | Its balance of corrosion resistance, availability, and formability makes it a widely used coil grade. | Require application-specific review for chlorides, seawater, strong acids, high temperatures, or crevice conditions; 304L is not universally suitable. |
| Magnetic behavior after processing | Usually low magnetic permeability when annealed; rolling, bending, and forming can produce some magnetism. | Prevents incorrect rejection of otherwise conforming material when components have undergone significant cold work. | Use chemical analysis and mechanical testing for identification; define magnetic-permeability limits only when functionally necessary. |
| Traceability | Each production heat or lot should be identifiable through records linking the coil to its chemical and mechanical test results. | Supports quality control, recall management, project documentation, and regulatory compliance. | Check heat number marking, coil number, certificate consistency, packing list, and permanent or removable identification. |
| Recommended supplier qualification status | Evidence-based approval | A technically suitable supplier should demonstrate conformity, stable dimensional control, reliable delivery, and responsive corrective action. | Evaluate certificates, sample inspection, surface quality, dimensional capability, packaging, lead time, nonconformance history, and after-sales support. |
