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Designation: A 255 – 02

Standard Test Methods for

Determining Hardenability of Steel1
This standard is issued under the fixed designation A 255; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates aneditorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.

1. Scope* 1.1 These test methods cover the identification and description of test methods for determining the hardenability of steels. The two test methods include the quantitative end-quench or Jominy Test and a method for calculating the hardenability ofsteel from the chemical composition based on the original work by M. A. Grossman. 1.2 The selection of the test method to be used for determining the hardenability of a given steel shall be agreed upon between the supplier and user. The Certified Material Test Report shall state the method of hardenability determination. 1.3 The calculation method described in these test methods is applicable only tothe range of chemical compositions that follow:
Element Carbon Manganese Silicon Chromium Nickel Molybdenum Range, % 0.10–0.70 0.50–1.65 0.15–0.60 1.35 max 1.50 max 0.55 max

2. Referenced Documents 2.1 ASTM Standards: E 18 Test Methods for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials2 E 112 Test Methods for Determining the Average Grain Size2 END-QUENCH OR JOMINYTEST 3. Description 3.1 This test method covers the procedure for determining the hardenability of steel by the end-quench or Jominy test. The test consists of water quenching one end of a cylindrical test specimen 1.0 in. in diameter and measuring the hardening response as a function of the distance from the quenched end. 4. Apparatus 4.1 Support for Test Specimen—A fixture for supporting the testspecimen vertically so that the lower end of the specimen is a distance of 0.5 in. (12.7 mm) above the orifice of the water-quenching device. A satisfactory type of support for the standard 1.0-in. (25.4-mm) specimen is shown in Fig. 1.
NOTE 1—A suitable support for other sizes and shapes of specimens is shown in Fig. X1.1.

1.4 Hardenability is a measure of the depth to which steel will hardenwhen quenched from its austenitizing temperature (Table 1). It is measured quantitatively, usually by noting the extent or depth of hardening of a standard size and shape of test specimen in a standardized quench. In the end-quench test the depth of hardening is the distance along the specimen from the quenched end which correlates to a given hardness level. 1.5 The values stated in inch-pound unitsare to be regarded as the standard. The values given in parentheses are for information only. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

4.2Water-Quenching Device—A water-quenching device of suitable capacity to provide a vertical stream of water that can be controlled to a height of 2.5 in. (63.5 mm) when passing through an orifice 0.5 in. (12.7 mm) in diameter. A tank of sufficient capacity to maintain the water temperature requirements of 6.3 with a small pump and control valves will be found satisfactory. The water-supply line shall also beprovided with a quick opening valve. 5. Test Specimens 5.1 Wrought Specimens—End-quench specimens shall be prepared from rolled or forged stock and shall represent the full cross section of the product. If negotiated between the supplier and the user, the end-quench specimen may be prepared from a given location in a forged or rolled product or from a

1 These test methods are under the...