"Effect of Plasma Nitriding On Fatigue and Wear Behavior of AISI 4330 Low Alloy Steel"
Crank shafts made of AISI 4330 low alloy steel used in oil field industries is subjected to rotating bending fatigue and wear. Forged crankshaft in hardened and tempered condition after finish machining is therefore subjected to plasma nitriding.
In this study the fatigue and wear behavior of plasma nitrided AISI 4330 steel were investigated under different process parameters. It was found that the plasma nitriding improves the surface hardness from 30 to 50 HRC. The case depth was found to increase with increase in nitriding time and temperature. With increase in case depth the fatigue strength of AISI 4330 improves up to 90%. The fatigue fractured surface examined under SEM revealed fish eye fracture. With increase in case depth wear resistance was also found to increase. The reason for increase in fatigue life and wear resistance as well as the mode of fracture are discussed.