
106 Engineering Materials Technology
There is an approximate relationship between hardness values and tensile
strengths. Thus for annealed steels the tensile strength in MN/mm
2
(MPa) is
about 3.54 times the Brinell hardness value, and for quenched and tempered
steels 3.24 times the Brinell hardness value. For brass the factor is about 5.6
and for aluminium alloys about 4.2.
5.3 Impact tests
Impact tests are designed to give a measure of the response of a material to a
sudden high rate of loading. There are two main forms of such test, the Izod
and the Charpy tests. In both tests a heavy pendulum swings through an arc
and strikes a notched tes ...