OpenSpecEngineering

The complete hardness conversion tables of ASTM E140-02 [1], for quality, heat-treat and materials engineers who measured on one scale and need the equivalent on another. Rockwell, superficial Rockwell, Brinell, Vickers, Knoop and Scleroscope numbers are given as the standard prints them, table by table for each material group.

What the page covers

• Hardness Conversion Picker: choose the material group, the scale measured and the reading, and the card shows that printed row on every other scale.
• Rockwell Scales in These Tables: the force and indenter of each Rockwell scale, and which tables use it.
• Tables 1 to 9: steels (HRC and HRB ranges), nickel alloys, cartridge brass, austenitic stainless plate and sheet, copper, alloyed white irons and wrought aluminum. Each has a filter box for finding a number.

Reading the tables

Each column heading gives the scale symbol and its test force, so HBW is a 10 mm carbide ball at 3000 kgf. A dash means the table has no entry. Parentheses mean different things in different tables, and the note under each table says what. In Table 1 they mark Brinell values outside the range E10 recommends. The Rockwell B range of Table 6 adds a Std. dev. row: the scatter of the test data about each conversion line.

Limits and common mistakes

• Use only the table for your material group. Alloy, heat treatment and cold work all shift a conversion, so a steel row says nothing about brass.
• The picker shows printed rows only and does not interpolate. For a reading between rows, use the Hardness Conversion calculator. It interpolates Table 1 of the later E140-12b(2019)e1 edition.
• A conversion is approximate. Convert only when the specified test can’t be made, and report the measured value with the converted one.
• These tables give no tensile strengths.

Worked example

A drawing calls for 300 HBW minimum on a quenched and tempered 4140 steel shaft. Inspection has only a Rockwell C tester. Find the lowest HRC reading that passes.

1. In the picker, choose Material group (E140 table) Steels, HRC range (Table 1) and Scale measured HRC — Rockwell C.
2. Choose Reading 32. The card shows: 32 HRC — Table 1
   Vickers (HV) 318
   Brinell, 10-mm carbide ball, 3000 kgf (HBW) 301
   Rockwell superficial 30-N (HR 30-N) 52.1
3. Choose Reading 31. The card shows HBW 294, below the minimum.

So 32 HRC is the lowest passing reading, and the report reads 32 HRC (301 HBW). Check: for steels in this range, HV runs about 5 % above HB. Here 318 / 301 = 1.06. Table 1 covers 4140 because it is a homogeneous, quenched and tempered alloy steel that is not austenitic.