Experimental study of the abrasive wear behaviour of plasma-nitrided gearing steel

Abstract

An increase in the wear resistance of AISI 722M24 steel can be achieved by the use of plasma nitriding, which produces a hard surface layer on the steel. The wear test in this investigation uses 10% carborundum powder in SAE-30 oil and emery paper with different grit sizes as the abrasive media. The plasma-nitrided samples were fully characterized using metallographic, X-ray diffraction and microhardness techniques before wear testing. Testing was carried out on a compact laboratory rig, over ranges of test loads and times. Plasma-nitrided AMS 6472 steel was used as the counterface material, with lubricated abrasive conditions. The tests carried out with the emery papers were performed by rubbing specimens against the different emery papers on a grinding wheel. The worn surfaces were examined using scanning electron microscopy. The test results show that the surface hardness and compound layer thickness are more important than the case depth in preventing weight loss. Also, the operating speed and abrasive grit size have an important effect on the mass loss of the plasma-nitrided steel.