The influence of Cu and Ni on tensile and fatigue behavior of Fe-0.85Mo prealloy with 0.6% graphite addition was investigated. The transient liquid phase formed by the presence of Cu resulted in more rounded pores in the Fe-Ni-Cu alloy compared to Fe-Ni. While the total porosity was similar in both alloys, a larger fraction of secondary pores was present in the Fe-Ni-Cu. The addition of Cu resulted in an increase in proportional limit stress, ultimate tensile strength, and fatigue strength over the Cu-free alloy. The higher fatigue resistance was attributed to the enhanced solid solution strengthening provided by Cu in Fe, and the higher proportional limit in the Fe-Ni-Cu alloy, caused by the more rounded nature of the pores, and stronger Fe-Ni-Cu matrix surrounding the pores. The proportional limit stress appears to be a good indicator of fatigue strength, since it quantifies the onset of localized plasticity in these materials.
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