Gigacycle Fatigue Properties of Double-Melted SCM440 Steel and Size Effects

Abstract

Gigacycle fatigue tests were conducted on double-melted SCM440 low-alloy steel using larger and conventional specimens and comparing the results with those of single-melted steel. Although all specimens experienced internal fractures, size effects were minor in the double-melted steel, unlike in the singlemelted steel: specifically, for the double-melted steel, differences in fatigue strength and inclusion size were minimal between the larger and conventional specimens. These results mean that the double-melted steel showed superior gigacycle fatigue properties to the single-melted steel when the larger specimens were used in the fatigue tests, whereas this superiority was doubtful when conventional specimens were used. When the inclusion sizes were estimated using the results for the larger specimens, the inclusion size for 150 kg of the double-melted steel was a maximum of 47 μm, one-third of that for the singlemelted steel. The use of larger specimens is thus highly advisable for evaluating the gigacycle fatigue properties and the inclusion size of high-strength steels.

VHCF ultrasonic tests on EN AW‐6082 aluminum alloy samples over a wide dimensional range

“…To this aim, a nodal harmonic acceleration at the upper free end of the specimen was imposed. As a consequence, the stress concentration factor, , evaluated according to Tridello et al, 37 and the risk volume, , 22,38,39 were obtained by the harmonic response analysis.…”

Experimental Evidence of Specimen-Size Effects on EN-AW6082 Aluminum Alloy in VHCF Regime

“…Subsequently, an harmonic analysis was performed to determine the stress concentration factor, k t , which is evaluated according to [14]. In addition, the risk-volume has been evaluated, V 90 , which is usually defined as the region where the stress amplitude is higher than the 90% of the peak value [9,11,28]. The above-mentioned dynamic mechanical properties of three different specimens, as well as the risk-volume, are summarised in Table 3, whereas Figure 2 shows a photograph of the specimens.…”

Experimental Evidence of Specimen-Size Effects on EN-AW6082 Aluminum Alloy in VHCF Regime

“…Subsequently, an harmonic analysis was performed to determine the stress concentration factor, k t , which is evaluated according to [25]. In addition, it has been evaluated the risk-volume, V 90 , which is usually defined as the region where the stress amplitude is higher than the 90% of the peak value [6,8,26]. The above-mentioned dynamic mechanical properties of three different specimens, as well as the risk-volume, are summarised in Table 3, while Figure 2 shows a photograph of the specimens.…”