A quotation says “hardness 250”, an inspection record reports HRC, and a drawing calls for HV. Before accepting or rejecting the steel, establish which result, location and material condition are being compared. BVM editorial, 18 October 2026.
Read the scale with the number
For metals, hardness generally concerns resistance to indentation. TWI Part 1 explains ball indentation for Brinell and a pyramidal diamond for Vickers.
| Marking | What to retain in the record |
|---|---|
| HB / HBW | Brinell result, original notation and test conditions |
| HRC | Rockwell C result, including the scale letter |
| HV | Vickers result, with the stated test load |
See the scales in Buehler's comparison chart. A larger number on a different scale does not by itself mean a harder material.
A converted value is not a new measurement
Buehler labels its conversion values as approximate. BVM recommends retaining the original reading, original method and conversion basis, rather than presenting a converted number as a direct test. TWI Part 2 also describes portable instruments displaying converted results. If results differ, agree on a reference test and inspection provider before making an acceptance decision.
BVM purchasing checklist
Specify the condition to be checked: delivered stock or material after the customer's processing. Agree on the test location, scale, method, acceptance range, sampling and response to unusual results under the applicable purchase documents. Link each specimen and report to the relevant heat or batch.
A useful question is: “Does the hardness requirement apply at stock delivery or after heat treatment? Please provide the original reading and test location.”
BVM's recommendation: assess hardness alongside the complete order requirements. Do not use one reading to certify the grade or replace agreed documentation and other tests. Resolve a missing scale on the drawing before pricing and delivery. There is no universal hardness requirement for every steel grade.
Sources: TWI Part 1, Part 2 and Buehler hardness comparison chart, checked 18 October 2026. No clear publication date is displayed on these technical resources. This is an educational article, not a report of a new standard. Cover: AI-created BVM illustration with the authentic BVM logo; not an inspection photograph or evidence of batch compliance.
