Abstract
To investigate the influence of the load ratio ΔK_<III>/ΔK_I, degree of overlap and material on the fatigue crack growth, mixed mode I and III tests were carried out on the normal rail steel and head hardened rail (HH340) steel. It was found that the growth rates became higher when the ratio ΔK_<III>/ΔK_I was decreased. It was also shown that the growth rate of HH340 steel was lower than that of normal rail steel. A non-linear weighting between ΔK_I and ΔK_<III> was used to fit the data empirically to the Paris type growth laws.
