VHCF Response of Two AISI H13 Steels: Effect of Manufacturing Process and Size-Effect

In the last decades, the fatigue lifetime of structural components has increased significantly and in many industrial applications (aerospace, automotive, and energy production industry) is even larger than 10(10) cycles. Therefore, the interest in the Very High Cycle Fatigue (VHCF) behavior of materials has grown rapidly, becoming a subject of primary interest among university and industries. In high-strength steels, VHCF failures generally originate from defects/inclusions; consequently, the steel cleanliness significantly affects the VHCF response. Furthermore, since the probability of finding critical defects in a loaded volume increases with the loaded volume, the loaded volume also significantly affects the VHCF response. This is generally referred to as the "size-effect" in VHCF. The present paper investigates the effects of the manufacturing process and the size-effect on the VHCF response of an AISI H13 steel. Experimental tests were performed on hourglass and Gaussian specimens made of two different types of AISI H13 steels: Unrefined H13 and refined Electroslag Remelting (ESR) H13. The analysis of variance (ANOVA), which was carried out on the test results, and the P-S-N curves showed that the two factors (i.e., the manufacturing process and the size-effect) significantly affect the VHCF response.