A. Celik et S. Karadeniz, IMPROVEMENT OF THE FATIGUE-STRENGTH OF AISI-4140 STEEL BY AN ION NITRIDING PROCESS, Surface & coatings technology, 72(3), 1995, pp. 169-173
The influence of plasma nitriding on the fatigue behaviour of AISI 414
0 low-alloy steel was investigated under varying process conditions of
temperature (500-600-degrees-C), time (1-12 h), heat treatment before
ion nitriding (quenched and tempered, normalized) and gas mixture (50
% H2-50% N2). A rotating bending fatigue machine was used to determine
the fatigue strength. It was found that the plasma nitriding improves
the fatigue strength and increases the fatigue limit depending on the
surface hardness of the case depth. The microstructure of surface and
diffusion layers was examined by optical microscopy. The fracture sur
face of specimens and the origin of fatigue cracks were observed by sc
anning electron microscopy.