engleski

The influence of thermal treatment on the low-cycle fatigue behaviour of Cu-Ni-Mo sintered steel

In this study, an investigation of the low-cycle fatigue properties of diffusion alloyed Cu-Ni-Mo sintered steel (as-sintered specimens) with consideration of additional heat treatment effects (as-hardened specimens) is presented. The microstructure of this powder metallurgy steel was found not uniform for both as-sintered and as-hardened specimens. The experimental testing was performed in a low-cycle fatigue regime on the servo-hydraulic testing machine under load control with stress ratio R = 0.1. The experimental results have shown that additional hardening increases the fatigue strength of the material significantly. Furthermore, the fatigue cracks propagated mainly through the regions with the highest porosity. The as-sintered specimens exhibited a combination of brittle and ductile fracture, while the as-hardened specimens exhibited predominantly ductile fracture. By determining low-cycle fatigue parameters, it is possible to further enhance the estimation of the number of loading cycles required for the fatigue crack initiation of different sintered machine parts and structural elements, while considering the effect of additional hardening due to the heat treatment processes.

Sintered steel ; Powder metallurgy ; Low cycle fatigue ; Experimental testing

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