A356‐T6 wheels: Influence of casting defects on fatigue design

Abstract

Rotating bending fatigue tests were executed on A356‐T6 wheels. The tests were performed both on components containing only the casting defects and on wheels in which artificial holes were machined. Results show the detrimental effect of sub‐superficial porosities on fatigue endurance. A predictive model was proposed. It resulted in a useful tool for the designer because knowing the applied stress, it is possible to estimate the number of cycles for crack nucleation considering the size of the defect, whereas knowing the endurance target requested it is possible to find the maximum defect size acceptable considering the applied stress.

The influence of defect and temperature on the fatigue behaviours of Al‐Si‐Cu‐Mg‐Ni alloy

“…Comparison of S ‐ N curves of both alloys tested at A, 350°C and B, 425°C (data of alloy B were from Tebaldini et al) [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…Initiation patterns of fatigue cracks (data of room temperature were from Tebaldini et al, Mbuya et al, and Joyce et al)…”

“…The different propagation modes reflect the different damage mechanisms at 350°C and 425°C. Secondary FIGURE 4 Initiation patterns of fatigue cracks (data of room temperature were from Tebaldini et al, 10 Mbuya et al, 30 and Joyce et al 35 ) cracks near the fatigue initiation sites are shown in Figure 7. Microcells comprising cracks formed in matrix at 350°C shown in Figure 7A.…”

“…Defects in cast Al‐Si alloys usually refer to as pores and oxide films . Numerous studies show that fatigue cracks predominantly initiate from defects and fatigue life decreases as defect size increases .…”

“…Defects in cast Al-Si alloys usually refer to as pores and oxide films. [6][7][8][9][10] Numerous studies show that fatigue cracks predominantly initiate from defects and fatigue life decreases as defect size increases. [11][12][13][14][15][16] Fatigue cracks nucleated from defects were defined as short or small cracks.…”