Hardness Scale Converter (HRC/HB/HV/HRB/Mohs) mechanism

Model scope

The steel HRC/HB/HV vectors are valid lookup-table tests using commonly reproduced ASTM E140 steel values, with the third vector explicitly testing linear interpolation. The Mohs vector is a boundary and rejection test: Mohs 10 is a standard table entry, but ASTM E140 supplies no universal conversion from it. The implementation needs a versioned table source, explicit material classes, valid ranges, interpolation policy, and a separate documented tensile-strength convention before it can be labeled as a complete converter.

• ASTM E140 provides conversion tables for specified hardness scales and material groups, but it does not provide a universal Mohs-to-Rockwell/Brinell/Vickers conversion; Mohs conversion must be rejected or supported by a separately identified material-specific table.
• The specification names steel-specific ASTM E140 data but also accepts arbitrary material classes; tables for non-steel alloys and the allowed material-class values are not defined.
• Interpolation is not specified. Linear interpolation between tabulated points is a reasonable engineering approximation, but it must be explicitly labeled as an interpolation convention rather than an exact ASTM result.
• Approximate tensile strength is not determined by a universal hardness formula. It requires a clearly identified steel-only correlation/table, with applicable composition and hardness-range limits.
• HRB and HRC ranges, test-force conventions, and handling of conversions outside the valid ASTM E140 ranges are unspecified.

Units and conventions

• Hardness values are dimensionless scale readings: HRC, HRB, HB, HV, and Mohs must retain their scale labels; they are not interchangeable physical units.
• Tensile strength, when supplied, is reported in MPa.
• The steel conversion fragments below use the commonly reproduced ASTM E140 steel table convention; exact values can vary by ASTM edition, table, alloy, and rounding convention.
• Linear interpolation is performed on the numerical hardness values and on the tabulated tensile-strength estimates.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "hardness_value": 30,
    "input_scale": "HRC",
    "material_class": "steel"
  },
  "expected_outputs": {
    "HRC": 30,
    "HB": 286,
    "HV": 302,
    "approx_tensile_strength_MPa": 1010
  },
  "reference_data": {
    "table_type": "Rockwell C to Brinell/Vickers/tensile strength, steel",
    "HRC_30": {
      "HB": 286,
      "HV": 302,
      "approx_tensile_strength_MPa": 1010
    },
    "source_convention": "ASTM E140 steel conversion table convention, widely tabulated standard value"
  },
  "working": "Input is exactly the HRC 30 row. Therefore HRC = 30, HB = 286, and HV = 302 with no interpolation. The steel-table tensile estimate is 1010 MPa."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The principal breaks are out-of-domain hardness values that must be rejected rather than interpolated, plus ambiguity when a bare hardness number or tensile-strength unit is supplied. A lookup engine that silently extrapolates HRC 0 or HRC 1,000,000, or assumes an unlabeled scale, can return materially misleading results.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json