Grade Markings for Metric Fasteners

Documents

Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.

Quotation

• The fastener family (Grade Markings for Metric Fasteners) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
• Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
• Quantity per size and your target delivery date.
• Destination country, and any required documents (for example a mill test certificate) so the quote includes them.

Sample & supply

Minimum order quantity is 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 days. Quantities or variants outside the standard range are confirmed at quotation.

Storage & shipping

Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.

A drawing calls class 10.9 but the delivered bolts show an underlined 10.9. Is that a reject?

No — it is a declared variant, and the underline is how you tell which one you have. The source's footnote carries the ISO rule: when low carbon martensitic steel is used for class 10.9, the symbol is underlined. Both steels meet the 10.9 mechanical minimums on the certificate, but they differ in ways that matter to some joints: quenched-and-tempered medium carbon vs low carbon martensite behaves differently at elevated temperature, under hydrogen charging, and in fire scenarios, and several industry specifications restrict the low-carbon-martensitic variant for those service conditions. So the response is documentation, not rejection: read the certificate, confirm the service allows the martensitic variant, and where the joint specification is silent but service is critical, resolve with the drawing owner before installation. What does justify rejection is missing or ambiguous marking altogether — the source's mandatory-marking note makes manufacturer's mark plus class identification a requirement, not a nicety, for hexagon and socket head cap screws above 5 mm diameter.

How do I decode the clock symbols on metric nuts?

ISO 898-2 allows the nut class to be marked either as the numeral (4, 5, 6, 8, 10, 12, and the thin-nut classes 04/05) or as a clock symbol — a dash/radial mark whose clock-face position on the nut face encodes the class. The mapping is fixed by the standard (e.g. the 12 o'clock single dash for class 4, moving clockwise by class; 04 and 05 use their own positions on the left side of the face), which is why this chart carries the code row honestly blank: the collected table's symbols are images, and a reconstructed description of a clock face is a poor substitute for the standard's own figure. The practical decoding habit that matters more than memorizing positions: mark presence is mandatory at d ≥ 5 mm, the manufacturer's mark must accompany the class mark, and an embossed marking is only acceptable if it does not protrude beyond the bearing surface — a raised emboss on the face you torque against is itself a defect. For a mixed receipt of nuts, sort by marking first and verify against the certificate; an unmarked high-strength nut is scrap for structural use regardless of how it hardness-tests.