Development of High Fatigue Strength Maraging Steel for CVT Belt

High fatigue strength is required for maraging steel for CVT belts. Two types of next generation maraging steels for CVT belts were studied using the following conditions, (a) increasing tensile strength, (b) increasing compressive residual stress on the nitrided surface, and (c) no addition of Ti. AlloyB (Fe-19%Ni-5%Co-5%Mo-1%Cr-0.8∼1.5%Al, %=mass%) with low Co and AlloyC (Fe-19%Ni-12.5%Co-5%Mo-0.5∼1%Cr,%=mass%) with high Co, were developed by additions of optimized amounts of Al and Cr, which are based on different strengthening ideas of Ti addition. These maraging steels showed tensile strengths and fatigue strengths equal to or better than those of conventional Ti-containing maraging steels.