ASTM E140
Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness
Standard hardness conversion tables relating Brinell, Vickers, Rockwell, Rockwell superficial, Knoop, Scleroscope and Leeb hardness for non-austenitic steel, austenitic stainless steel, nickel and high-nickel alloys, cartridge brass, copper, alloyed white iron and wrought aluminum products.
What ASTM E140 specifies
ASTM E140 collects the empirically derived conversion tables that let one hardness scale be expressed approximately in another. Table 1 (non-austenitic steels, Rockwell C range) is the one heat treaters use daily: 60 HRC is about 697 HV and 654 HBW; 50 HRC about 513 HV and 481 HBW; 40 HRC about 392 HV and 371 HBW; 30 HRC about 302 HV and 286 HBW, with an approximate tensile-strength column alongside. Separate tables cover the Rockwell B range for steel, nickel and high-nickel alloys, cartridge brass, austenitic stainless sheet and plate, copper, alloyed white cast iron and wrought aluminum (Rockwell B/E/H versus Brinell), plus Leeb rebound conversions. The standard states that conversions are approximate, valid only for the material class of the table, and may be used for acceptance only when the applicable specification or the purchaser agrees; ASTM E18 and E10 refer to it for exactly that purpose.
Tests and the drawing call-out
Tests the document imposes
- Not a test method: conversions apply only to hardness values obtained per ASTM E18, E10, E384, E448 (Scleroscope) or A956 (Leeb) on the material class of the table
How to cite it
Drawing call-out
HARDNESS 40–45 HRC PER ASTM E18 (HBW EQUIVALENT PER ASTM E140 ACCEPTABLE ON SECTIONS OVER 25 MM)Angle brackets mark the choices the drawing must make; every finish page shows a completed example.
Heat treatments specified to ASTM E140
| Treatment | Role | Cost |
|---|---|---|
Gas nitriding diffuses nitrogen into finished ferrous parts below the transformation temperature, producing a hard compound layer and diffusion zone without quenching. | Related | $$$$ |
High-temperature tempering reheats quenched steel around 500–650 °C to produce tempered martensite with high toughness and moderate hardness. | Related | $ |
Induction hardening uses an alternating magnetic field to austenitize selected steel surfaces, followed immediately by quenching. | Related | $$ |
Low-temperature tempering reheats freshly quenched steel at about 150–250 °C to relieve stress while retaining high martensitic hardness. | Related | $ |
Medium-temperature tempering reheats quenched steel around 300–450 °C to trade some hardness for strength, elasticity, and improved toughness. | Related | $ |
Plasma nitriding uses a glow discharge to clean, heat, and diffuse nitrogen into ferrous surfaces. | Related | $$$$ |
ASTM E140 — frequently asked
Can the heat treater accept my 40–45 HRC part with a Brinell test?
Only if the drawing or the governing specification permits conversion — as this callout does, or as ASTM A564 does by listing both HB and HRC. Then 40–45 HRC reads as 371–421 HBW per Table 1; without that permission the scale on the drawing is the acceptance scale.
How accurate are the conversions?
Within a few points for the material the table was built on — non-austenitic steel between 20 and 68 HRC — and unreliable outside it: austenitic stainless, cold-worked nickel alloys, aluminum, cases and coatings all deviate, which is why E140 publishes separate tables and warns against using Table 1 for everything.
What tensile strength does a hardness imply?
Table 1 carries an approximate tensile column for steel: roughly 965 MPa (140 ksi) at 30 HRC and 1250 MPa (181 ksi) at 40 HRC. That relationship is why AMS 2759/1 tensile classes have hardness equivalents (180–200 ksi is about 39–43 HRC) — but it is approximate, and tensile tests remain the acceptance test where the drawing requires them.
Why is austenitic stainless treated separately?
Work hardening under the indenter and the absence of martensite change the relationships between Rockwell, Brinell and Vickers compared with carbon steel, so E140 provides separate tables for austenitic stainless sheet and plate; applying the steel table to 304 can misstate hardness by several HRB points.
ASTM E140 is copyrighted by ASTM International. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗