Origin of Ductile Fracture in Aluminum Alloys

Ductile fracture via hydrogen pore mechanism in an aluminum alloy; quantitative microstructural analysis and image-based finite element analysis

“…Although many voids were found to nucleate at matrix/particle interface, it was also found that the pre-existing hydrogen pores became much larger by the time the macroscopic fracture event occurs. It is highly possible that these significantly grown hydrogen pores get linked with the neighboring pores and with the voids that are being nucleated during deformation, being a primary mechanism of ductile fracture in the alloy as pointed out by Toda et al [6]. The evolution of the porosity as a function of axial strain is shown in Fig.…”

“…Moreover, Toda et al [6] have recently performed XMT using synchrotron radiation to observe the ductile fracture process of a 2024 aluminum alloy, revealing that the ductile fracture in its material does not occur through a conventional ductile fracture mechanism (i.e. growth and coalescence of voids nucleated at inclusions/particles) [15][16][17][18][19][20][21][22][23] but through the simple catastrophic linkage of hydrogen pores as shown in Fig.…”

“…X-ray microtomography = XMT)) [1][2][3][4][5][6][7][8][9], 4D image quantitative analysis [1,3,10,11] and image-based finite element analysis (IB-FEA) [12,13] is remarkable.…”

Effects of Hydrogen Micro Pores on Mechanical Properties in A2024 Aluminum Alloys

“…4,5) The effects of micro pores on damage evolution are more pronounced when a notch or a crack is introduced to a specimen. 6) More recently, it has been revealed that pre-existing hydrogen micro pores also contribute to cavitation during high temperature deformation. 7) It is therefore reasonable to assume that the mechanical properties of aluminum alloys are more or less improved by eliminating micro pores in aluminum alloys.…”

“…It has been reported by the present authors that triaxial stress state ahead of a notch and a crack exerts a marked effects on the premature growth of micro pores. 6) Notched tensile tests and fracture toughness tests are performed to examine such effects on macroscopic material properties. Synchrotron Xray microtomography is also applied to perform the in-situ observation of damage evolution behaviors in order to obtain the experimental evidence of the effects of micro pores.…”