Hardness Conversion Chart

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 (Hardness Conversion Chart) 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 10,000 pieces. Stock items run 3–7 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 HRC 32 minimum but the mill certificate reports HV. Can I use this chart to accept the part?

Use the chart to understand, not to accept. Conversion tables are approximations — the same HRC value corresponds to a band of HV depending on where in the range you sit — and acceptance decisions should be made in the scale the specification names. The correct path when scales mismatch is to have the laboratory report in the governing scale (Vickers is the ISO 898-1 preferred method precisely because it reads the whole fastener range on one scale), or to fall back on the standard's own conversion procedure where it permits one. What this chart is genuinely for is orientation: checking that a certificate's numbers sit in the right neighbourhood before a detailed review, or translating a supplier's HRC claim into the HV scale your incoming test uses. And a caution the chart itself demonstrates: its HRC 32 row prints HV 1309 — a transcription-grade error on the collected page — which is exactly why converted values never substitute for a tested one.

Why does the chart switch from HRC to HRB partway down, and where do the property classes sit?

Because the Rockwell scales cover different hardness territory: HRC uses a diamond cone and heavy load for hardened steels, HRB a steel ball and lighter load for soft steels and copper — an HRC reading on soft material simply does not resolve, and vice versa. The chart's overlap band (roughly HB 241 down to HB 81, HRB 100 to 36) is where both ball-scale reading and conversion are meaningful. The fastener property classes sit in the HRC territory: ISO 898-1 sets hardness requirements for class 8.8 around HRC 22-32 depending on size, 10.9 around HRC 32-39, 12.9 around HRC 39-44 — all inside this chart's HRC ladder, which is why the chart is useful for fastener work specifically. Below the overlap (the bare HB/HV rows at the bottom), you are in soft steels and case-hardened cores — HRB territory where the chart's HRB column is the reading to match certificates against.