METHODS OF DETERMINING HARDENABILITY OF STEELS J406C_197712

This SAE Standard prescribes the procedure for making hardenability tests and recording results on shallow and medium hardening steels, but not deep hardening steels that will normally air harden.

Included are procedures using the 1 in (25 mm) standard hardenability end quench specimen for both medium and shallow hardening steels, Surface-Area-Center (SAC) method for shallow hardening steels, subsize method for bars less than 1 1/4 in (32 mm) in diameter, and methods for determining carburized hardenability.

Any hardenability tests made under other conditions than those given in this SAE Standard will not be deemed standard and will be subject to agreement between supplier and user. Whenever check tests are made, all laboratories concerned must arrange to use the same alternate procedure with reference to test specimen and method of grinding for hardness testing.

For routine testing of the hardenability of successive heats of steel required to have hardenability within certain limits, it is sufficient to designate hardenability simply in terms of distance from the quenched end to the point at which a certain hardness is obtained. This designation is also adequate for comparing steels of different compositions to see whether they have similar hardenability.

Hardenability limits for specifying steel in this manner are obtained by measuring the hardenability of a steel which has proved satisfactory for the use intended. The hardenability test may be used in this way as an empirical test.

Hardenability data may be used to estimate hardnesses obtainable with any steel in new machine parts not yet in production and not similar to any parts on which production experience is available. Various hardenability application methods are described in the selected references in the Bibliography. It appears none of these methods are precise, but these are often useful for estimation purposes. Final correlation on actual parts is necessary.