The Improvement of High Cycle Fatigue Properties of AC4CH Alloy with Shot Peening Treatment

2005 ◽  
Vol 297-300 ◽  
pp. 1919-1924
Author(s):  
Kiyotaka Masaki ◽  
Yasuo Ochi ◽  
Takashi Matsumura
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Crack Propagation Rate ◽  
Fatigue Properties ◽  
Fatigue Crack Propagation Rate ◽  
Cycle Fatigue

In order to investigate the effect of SP treatment on the high cycle fatigue properties such as fatigue strength, crack initiation and propagation behaviors, rotating bending fatigue tests on shot-peening (SP) treated AC4CH aluminum alloy were carried out. The fatigue properties of the SP-treated material were compared with fatigue properties of the non-peened material, the hot isostatic pressure (HIP) treated material and the semi-liquid (SL) die casting material. the main conclusions obtained were, (1) The fatigue properties of SP-treated material is most excellent in all materials. (2) The fatigue life property of AC4CH alloys is significantly affected by fatigue crack initiation behavior. The reason why the SP-treated material has longer fatigue life than those of other material is that it has no cast defects near the surface by the effect of SP treatment. (3) The reason of fatigue life improvement by SP treatment is decrease of fatigue crack propagation rate.

scholarly journals Interactions between geometrical defects and microstructure during high cycle fatigue of polycrystalline aluminium with different grain sizes

2018 ◽  
Vol 165 ◽  
pp. 14004
Author(s):  
Benoît Bracquart ◽  
Charles Mareau ◽  
Nicolas Saintier ◽  
Franck Morel
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Cycle Fatigue ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Geometrical Defects

In this work, the influence of the geometrical defect size on the high cycle fatigue behavior of polycrystalline aluminium with different grain sizes is investigated, to better understand the role of internal length scales. Two sizes of grains and defect are used: 100 μm and 1000 μm, the grain size being controlled with thermomechanical treatments. Fully reversed stress-controlled fatigue tests are then carried out. According to fatigue test results, surface crack initiation is delayed when the grain size is reduced, while an approximation of the fatigue limit shows that it is not much influenced by the average grain size. The relative defect diameter (compared to the grain size) seems to be the leading parameter influencing fatigue crack initiation from a defect. Finally, Electron BackScattered Diffraction (EBSD) maps are collected for specimens with large grains and small defects. Fatigue crack initiation from a defect is found to be strongly impacted by the crystallographic orientation of the surrounding grain, crack initiation preferably occurring in crystals being favorably oriented for plastic slip.

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