ASTM A686:16 pdf download

ASTM A686:16 pdf download.Standard Specification for Tool Steel, Carbon.
7. hardness Properties
7.1 Annealed hardness values shall be obtained in accordance with the latest issue of Test Methods and Definitions A370, and shall not exceed the Brinell hardness values (or equivalent Rockwell hardness values specified in Table 2.
7.2 Specimens for determination of minimum response to hardening shall be /4-in. (6.4-mm) thick disks cut so as to represent either the full cmss.sectional area or that midway between the center and outer surface of the material. If the material form or size docs not lend itself to accurate hardness determination on ¼-in. (6.4-mm) thick cross-sectional disks. then longitudinal specimens may be used for hardness testing. Examples are round bars less than ½ in. (12.7 mm) in diameter or sheet. In this case, the specimen shall be a minimum of 3 in. (76.2 mm) in length and parallel flats shall be ground on the original mill surfaces. The specimens shall be heat treated as prescribed in Table 3.
7.2.1 The hardness of the specimen after the specified heat treatment shall meet the minimum hardness value for the particular type of steel shown in Table 3. Rockwell C tests should he used where possible hut light load tests may he necessary on thin specimens. These tests should be specified by agreement between seller and purchaser. The hardness value shall he obtaird in accordance with the latest issue of Test Methods and Definitions A370. and shall be the average of at least five readings taken in an area midway between the center and surface of the largest dimension of the cross-sectional specimen or along the parallel surfaces of the longitudinal specimen. The surface to be tested shall be ground sufliciently to remove any surface condition, scale. carburization. or decarhurization which might affect readings.
7.2.2 Hardness penetration and fracture grain size for GradeA shall be determined on test pieces of 3/4 in. (19.1 mm)diameter and 3 in. (76.2 mm) length.Two pieces for each testshall be given a preliminary treatment by heating uniformly to1600 ±10°F (871 ± 5°C) and holding at temperature for40 min, then quenching in oil.One piece shall be reheated to1450± 10°F (788 ± 5C) and the other to 1550 ±10°F(843± 5°C).Each piece shall be held in the furnace at therespective temperature for 30 min and then quenched in brine(5 to 10 % sodium chloride solution). The pieces shall benicked with an abrasive wheel in the center of the length andfractured. The fracture face of one portion of each broken testpiece shall be ground smooth and etched in 1 + 1 muriatic acidat 165°F (74°C) for measurement of the depth of penetration tobe expressed in 64ths of an inch.The fracture grain size shallbe determined on the remaining portion of each broken testpiece by comparison of the fracture surface of the hardenedcase with the Shepherd Fracture Grain Size Standards. Thesestandards consist of ten pieces of steel with fracture facesrepresenting graduated grain sizes from the coarsest (No. 1) tothe finest (No. 10). The fracture grain size is estimated to thenearest quarter number. The hardness penetration and fracturegrain size for Grade A shall meet the requirements shown in Table 3.