Before investigating general abrasion of various metals, the writer made a study on the relative abrasion of various carbon steels at the state of sliding frictional condition per unit work, the coefficient of friction being kept constant. The test was carried out by means of an abrasion testing machine newly designed by the writer. The specimens were taken from Swedish steels in the form of hollow concentric cylinder specially designed, the content of carbon ranging 0・1〜0・9 percent. The cross sectional surfaces of the two specimens, A and B, were placed opposite each other. The contact surface had the form of concentric ring. The abrasion of both specimens was measured by means of sensitive balance ;and by measuring the frictional force at the contact surface, the frictional energy and coefficient of friction could be calculated. Some of the results obtained from the hypoeutectoid steel tested are as follows. If the passive specimens (rubbed specimens) are the same, the abrasion of the active specimens (rubbing specimens) against them becomes less as the content of carbon, that is hardness, increased. And the greater the difference in hardness between the active and passive specimens, the larger the difference of the relative abrasions of them. Again, if the following not*tions be used : W_<Nn>=Standard obrasion of a specimen, n, against the standard specimen, N, in mgr. W_<Nm>=Standard abrasion of a specimen, m, against the standard specimen, N, in mgr. W_<mn>=Re1ative abrasion of n against m, in mgr. W_<nm>=Relative abrasion of m against n, in mgr. then a simple relation [numerical formula] is found among the three abrasions W_<Nn>, W_<Nm> and W_<mn> or W_<nm> ; where K is a constant having the value of 7・8 when the coefficient of friction is 0・65,and N, n and m can take any content of carbon so far as present tests on the hypoeutectoid steels are concerned.

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We carried out the experiments on the wear of the materials for rolled steel type by Amsler universal wear testing machine. In these experiments, by rolling friction with slightly sliding friction we have experienced the resistance of a carbon steel containing about 0・55% of carbon with various structues to wear. The results are as follows : - (1) Rolled steel without any heat treatments has more resistance to wear than that of sorbitic structure (quenched at 820℃ and tempered at 600℃.). (2) The resistance to wear does not depend solely upon hardness, but also upon the structure of the steel. (3) The resistance to wear is greatly varied by the interchanging the position of the test piece. (4) Wear is chiefly affected by the steel powder which fallen off by abrasion, so that wear scarcely occured when the fallen powder were rubbed off during abrasion test. (5) Therefore, we come to conclusion that the were has little effect on the fatigue of materials.

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