Material-specific controlled-table lookup
Documented Hardness-Conversion Table Lookup
Use exact pairs copied from the licensed table applicable to the tested material and condition. Linear interpolation is available only when the controlled source or project procedure explicitly authorizes it.
Controlled-table result
Implemented arithmetic
Authorized linear mode: y = y₀ + (x−x₀)(y₁−y₀)/(x₁−x₀)
The second expression is ordinary piecewise-linear interpolation, not a universal hardness-conversion law and not automatically an ISO/ASTM requirement. The page never extrapolates beyond the entered table and does not round to a normative reporting resolution; apply the documented source rule entered above.
Current ISO source and scope
ISO 18265:2013, edition 2, was confirmed in 2024 and remains current. ISO states that its converted values are directly applicable only to the exact material tested; for other materials they are indicators, not replacements for the correct standard method. ISO also identifies tensile-strength estimates as the least reliable converted values.
ASTM material/table boundary
The official ASTM E140 standard page says conversion is approximate, table values are valid only for the specific indicated materials, confidence limits cannot generally be stated, and conversion of test data should be avoided where possible. Different tables cover non-austenitic steels, nickel alloys, cartridge brass, austenitic stainless products, copper, white iron and wrought aluminium; they are not interchangeable.
Why the former built-in converter was removed
The former page used only 10 HRC and 5 HRB points, linearly interpolated them as a universal ASTM E140 table, silently clamped values outside the range to an endpoint and generated tensile strength as 3.45×HB. It did not identify the applicable material table or test load. A 2026 ASTM work item specifically reports that the existing non-austenitic-steel table is not appropriate for martensitic stainless steels and that precipitation-hardened nickel-alloy data showed high dispersion.
Licensed source required: this page intentionally contains no ISO 18265 or ASTM E140 numeric tables. Copy only the rows and permitted interpolation/rounding rule from a legally accessed, controlled source applicable to the exact material and project purpose.
