Fretting of Hardened Steel in Oil

To determine the effect of hardness on fretting wear, tests of AISI 4340 steel were made in an oil bath using a new machine designed to make fretting corrosion tests with a wide range of parameters. Hardness values from 258 to 743 Vickers were tested, the hardest specimen having a nitrided surface. The fretting action used, 0.005 in. reciprocating motion at pressures from 430 psi to 5840 psi, produced much less fretting than similar tests in air, with little or no oxide products resulting. The galled areas were measured for depth of pit and height of deposit with the results indicating some small effects due to hardness up to 460 Vickers. The nitrided specimens, however, produced smaller fretted areas and the roughening of their surfaces was shallow.