| Material Grade | Exact grade designation, product form, delivery condition, and applicable standard. | The purchase order should identify a recognized specification, such as ASTM A36, ASTM A572 Grade 50, EN 10025 S275JR, or EN 10025 S355JR, according to the application. | Compare the quotation, order confirmation, mill test certificate, and product markings. | Descriptions such as “mild steel,” “structural steel,” or “equivalent grade” without a stated standard. |
| Chemical Composition | Heat analysis showing carbon, manganese, phosphorus, sulfur, silicon, and any required alloying elements. | Values must comply with the selected product standard and grade. For many structural grades, phosphorus and sulfur are controlled to approximately 0.035% or lower, but the exact limit depends on the standard and thickness. | Review the heat number, laboratory results, test method, and applicable standard limits on the certificate. | Only nominal chemistry is provided, or the certificate does not identify the heat from which the sheet was produced. |
| Yield Strength | Minimum yield strength for the ordered thickness range. | Typical examples include ASTM A36: minimum 250 MPa; ASTM A572 Grade 50: minimum 345 MPa; EN 10025 S355 for thickness up to 16 mm: minimum 355 MPa. Requirements vary with grade and thickness. | Check the mechanical test results against the specified standard and thickness category. | A single yield-strength value is quoted without identifying the test direction, thickness range, or standard. |
| Tensile Strength | Minimum and maximum tensile-strength range, where required by the standard. | Typical examples include ASTM A36: 400–550 MPa; ASTM A572 Grade 50: minimum 450 MPa; EN 10025 S355: commonly 470–630 MPa for thinner products. Confirm the exact grade and thickness. | Review the tensile test report, specimen direction, gauge dimensions, and test standard. | The supplier provides only “high tensile strength” wording without numerical test results. |
| Elongation | Minimum elongation requirement and the gauge length used for measurement. | The required percentage depends on the grade, thickness, and test method. A valid report should state whether elongation was measured over a 50 mm or 80 mm gauge length, or another specified length. | Confirm the gauge length, specimen orientation, test method, and result on the MTC. | Elongation is listed without gauge length or without identifying the applicable standard. |
| Impact Toughness | Charpy V-notch impact requirements where the application involves low temperatures, dynamic loading, or a notch-toughness specification. | For EN grades, suffixes such as JR, J0, and J2 indicate impact testing at +20°C, 0°C, and −20°C respectively. The required absorbed energy must be confirmed from the relevant standard. | Review impact test temperature, individual results, average result, specimen size, and test direction. | A supplier claims “impact resistant” without reporting test temperature or absorbed energy. |
| Thickness and Width | Nominal thickness, actual measured thickness, width, length, and permitted tolerances. | Tolerances should comply with the specified standard, such as ASTM A568/A6 requirements or EN 10029, rather than an informal supplier tolerance. | Use calibrated micrometers and steel tapes at multiple locations; compare measurements with the order and standard. | Measurements are taken at only one point, or the supplier refuses to state the applicable dimensional-tolerance standard. |
| Flatness and Shape | Flatness, edge camber, squareness, and surface-profile requirements. | Define the required class or tolerance before production. EN 10029, ASTM A6, or the agreed project specification may be used where applicable. | Inspect the sheet on a level surface using a straightedge, feeler gauges, and diagonal measurements. | Flatness is described as “standard” without a numerical tolerance or inspection procedure. |
| Surface Condition | Surface-finish description, permissible defects, scale condition, oiling requirement, and repair policy. | The specification should define acceptable scale, scratches, pits, laminations, rust, edge cracks, and repair marks. Surface quality must match the intended fabrication or coating process. | Conduct visual inspection under adequate lighting and use a surface comparator or depth gauge where necessary. | Heavy scale, deep pitting, visible laminations, unapproved weld repairs, or inconsistent surface condition across the bundle. |
| Ultrasonic Testing | Ultrasonic testing requirement, coverage, test class, acceptance level, and report linked to the heat or plate number. | UT is commonly required for critical or thicker plates to detect internal laminations and discontinuities. The applicable standard and acceptance class must be stated in advance. | Review the UT map, equipment calibration record, operator qualification, test standard, and acceptance result. | The supplier says the material is “fully tested” but provides no test scope, map, or acceptance criteria. |
| Mechanical Test Method | Test standards, specimen orientation, sampling frequency, and laboratory identification. | Tests should follow the ordered specification and an accepted method, such as ASTM A370 or EN ISO 6892-1 for tensile testing, where applicable. | Check the test method, machine identification, calibration status, specimen direction, and laboratory authorization. | Results contain no test method, no specimen information, or unexplained identical values across multiple heats. |
| Mill Test Certificate | Original or verifiable inspection certificate, preferably EN 10204 Type 3.1 for material-specific results. | A Type 3.1 certificate should identify the manufacturer, product, heat number, chemical analysis, mechanical results, dimensions, standard, and authorized inspection signatory. | Verify the certificate against the supplier’s document-control system and the physical markings on the material. | Generic certificates, editable spreadsheets, missing signatures, mismatched dates, or documents unrelated to the supplied heat. |
| Heat and Lot Traceability | Heat number, plate number, bundle number, production date, and traceability from raw material to shipment. | Every sheet or bundle should remain linked to the corresponding heat analysis and mechanical test results throughout cutting, processing, packing, and delivery. | Perform a traceability audit from the product marking to the packing list, MTC, inspection report, and shipping documents. | Markings are painted over, removed during cutting, or different documents show inconsistent heat numbers. |
| Product Marking | Permanent or durable identification on each sheet or bundle. | Marking should normally include grade, standard, heat number, dimensions, manufacturer identification code, and plate or bundle number as agreed in the order. | Photograph markings before dispatch and compare them with the MTC and packing list. | Only a temporary paper label is supplied, or markings are illegible after handling. |
| Independent Inspection | Third-party inspection scope, inspection and test plan, hold points, and final release documentation. | For safety-critical or regulated projects, independent inspection may include document review, dimensional checks, visual inspection, sampling, and witnessing of tests. | Confirm the inspector’s report, accreditation or qualification, inspection date, sampled items, and release status. | Inspection is offered only after shipment, or the supplier will not permit reasonable pre-shipment verification. |
| Coating and Corrosion Protection | Oiling, priming, galvanizing, or other corrosion-protection requirements, including coating thickness where applicable. | The protection system should be compatible with storage, transport, welding, painting, and end use. Coating thickness and test requirements must be defined when a coating is supplied. | Check coating certificates, dry-film thickness readings, visual condition, and packaging protection. | Unstated oil or coating prevents fabrication, or corrosion is visible under damaged packaging. |
| Weldability Information | Carbon equivalent, welding recommendations, delivery condition, and any preheat or heat-input guidance. | For carbon-manganese steels, carbon equivalent can be calculated from the reported chemistry. The actual welding procedure should be qualified for the grade, thickness, joint design, and service conditions. | Calculate the applicable carbon equivalent and review the qualified welding procedure before fabrication. | The supplier guarantees “easy welding” without chemistry data or without considering thickness and joint conditions. |
| Packaging and Logistics | Bundle weight, lifting points, protection against moisture, loading plan, and document package. | Packaging should prevent shifting, edge damage, and water accumulation during transport. Bundle labels and shipping documents must preserve full traceability. | Inspect packaging photographs, bundle condition, weight records, packing list, and transport documentation. | Wet packaging, unsupported overhangs, damaged edges, missing bundle labels, or incomplete shipping documents. |
| Nonconformance Control | Written process for handling rejected material, concessions, replacement, corrective action, and customer claims. | A reliable supplier should provide documented root-cause analysis and corrective action, with replacement or disposition subject to customer approval. | Review sample nonconformance reports, corrective-action records, response times, and closure evidence. | The supplier requests acceptance of deviations verbally or replaces documents instead of investigating the cause. |
| Supplier Qualification | Quality-management certification, process capability, production capacity, and relevant project experience. | A quality system certified to ISO 9001 can support process control, but certification does not replace product testing, inspection, or material traceability. | Verify certificate validity, scope, issuing body, production resources, and recent objective quality records. | An expired certificate, scope unrelated to steel products, or reliance on certification alone as proof of product conformity. |
| Commercial Reliability | Clear quotation, standard references, lead time, validity period, payment terms, and documented change-control process. | The quotation should state grade, dimensions, quantity, tolerances, testing, certificates, packaging, delivery basis, and all exclusions. | Compare the quotation with the technical specification and ensure all changes are approved in writing. | Unusually low pricing caused by omitted testing, unclear grade substitutions, or undocumented changes after order placement. |
