The Development of Residual Micro-Stresses Surrounding Various Inclusion Types in Wheel Steel

Non-metallic inclusions are known to have deleterious affects on fatigue resistance of steels and other metals and alloys. Non-metallic inclusions reduce fatigue life by changing the micro-stresses in the vicinity of a propagating crack. But, some non-metallic types have a greater affect on fatigue life than other, more benign non-metallic types. Residual micro-stresses surrounding a non-metallic inclusion is proposed as one solution as to why these differences exist. Specifically investigated were the non-metallic types of Alumina, Silica and Manganese Sulfide — all of which are found to some extent in AAR M-107/M-208 Class C wheel steel.