Fracture mechanism of AZ31 magnesium alloy processed by equal channel angular pressing comparing three point bending test and tensile test

Yu, Xiaoquan; Li, Yulong; Li, Li

doi:10.1016/j.engfailanal.2015.04.020

Cited by 24 publications

(4 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure shows typical SEM micrographs of the fracture surface for YCOB specimens with different orientations after bending tests. In terms of the fracture morphology, there are a lot of cleavage steps and only a few dimples in the fracture, indicating that the YCOB crystals broke as a brittle material . For cracks induced by a single cleavage plane (Figure d,e), the steps generated by crack propagation are obviously shallow and sparse.…”

Section: Results and Discussionmentioning

confidence: 99%

Study of Static Flexural Strength Anisotropy of Yttrium Calcium Oxyborate Crystals

Ren

Chen

et al. 2023

Crystal Growth & Design

View full text Add to dashboard Cite

As a promising optical and piezoelectric crystal, yttrium calcium oxyborate (YCOB) has been criticized for its easy fracture during both the cooling and machining processes. Herein, in order to evaluate the mechanical energy (G) required for crack propagation on one crystal plane, we measured the bending strength of the YCOB samples with different orientations via employing a three-point bending test. The surface topography of the polished sample was measured, and the average surface roughness is limited to 10 nm. Fracture surfaces were also observed and analyzed. The results showed that the bending strengths of Y-cut and Z-cut samples were higher than other cut directions in the XZ principal plane, showing obvious anisotropy. It can be found that the cleavage planes and (101) were always observed in fractured samples in multiple directions in the XZ principal plane. The contribution of the cleavage planes and (101) to the fracture of the specimens was discussed in detail by the theorem of energy minimum. Finally, based on the obtained scanning electron microscopy results, we propose the mechanism for crack advance in YCOB crystals. A perfectly brittle crack in a crystal prefers cleavage planes with low surface energy. It is believed that these findings may provide fresh ideas to overcome the cleavage fracture of larger size YCOB crystals.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Study of Static Flexural Strength Anisotropy of Yttrium Calcium Oxyborate Crystals

Ren

Chen

et al. 2023

Crystal Growth & Design

View full text Add to dashboard Cite

show abstract

“…Digital image correlation was used to monitor the strain field in the critical area during specific intervals of the fatigue loading, and trace its evolution over time to understand the influence of thermomechanical defects on the nucleation and early growth behaviour of fatigue cracks. Although using DIC techniques to measure the strain field surrounding the crack tip in notched specimens has been done by other researchers for magnesium alloys [29,30], in this study, conventional techniques for crack detection such as optical microscopy, x-ray scanning, and die-penetrant were not effective at locating the presence of an incipient crack or initial defect, as they generally are done with the component in a resting state under no load [31,32]. Furthermore, with the exception of x-ray, these conventional techniques are not typically effective for detection of subsurface defects as they require some evidence of the defect to have nucleated at the surface.…”

Section: Resultsmentioning

confidence: 99%

Effect of thermomechanical processing defects on fatigue and fracture behaviour of forged magnesium

Gryguc

Behravesh

Jahed

et al. 2020

Frattura Ed Integrità Strutturale

View full text Add to dashboard Cite

The microstructural origins of premature fatigue failures were investigated on a variety of forged components manufactured from AZ80 and ZK60 magnesium, both at the test specimen level and the full-scale component level. Both stress and strain-controlled approaches were used to characterize the macroscopically defect-free forged material behaviour as well as with varying levels of defect intensities. The effect of thermomechanical processing defects due to forging of a industrially relevant full-scale component were characterized and quantified using a variety of techniques. The fracture initiation and early crack growth behaviour was deterministically traced back to a combination of various effects having both geometric and microstructural origins, including poor fusion during forging, entrainment of contaminants sub-surface, as well as other inhomogeneities in the thermomechanical processing history. At the test specimen level, the fracture behaviour under both stress and strain controlled uniaxial loading was characterized for forged AZ80 Mg and a structure-property relationship was developed. The fracture surface morphology was quantitatively assessed revealing key features which characterize the presence and severity of intrinsic forging defects. A significant degradation in fatigue performance was observed as a result of forging defects accelerating fracture initiation and early crack growth, up to 6 times reduction in life (relative to the defect free material) under constant amplitude fully reversed fatigue loading. At the full-scale component level, the fatigue and fracture behaviour under combined structural loading was also characterized for a number of ZK60 forged components with varying levels of intrinsic thermomechanical processing defects. A novel in-situ non-contact approach (utilizing Digital-Image Correlation) was used as a screening test to establish the presence of these intrinsic defects and reliably predict their effect on the final fracture behaviour in an accelerated manner compared to conventional methods.

show abstract

“…From the core to the subsurface layer, the dimples gradually become smaller and shallower, and river-like patterns appear, which implying the transition from ductile fracture to cleavage fracture. The direction of river patterns merging is the direction of crack source [36]. As can be seen from Figure 7(f), the crack originates from the surface.…”

Section: Resultsmentioning

confidence: 99%

Improving mechanical properties for pure irons by local surface mechanical attrition treatment

Wei

Cui

Wei

et al. 2019

Materials Science and Technology

View full text Add to dashboard Cite

After a short-time surface mechanical attrition treatment process, a planar uneven structure was obtained on the surface of irons. The yield strength of the sample subjected to surface mechanical attrition treatment for 60 s is almost twice than that of the annealed sample, but the ductility is still well retained. The good combination of strength and ductility is mainly due to the extra strain hardening and the coexistence of soft and hard phases. The extra strain hardening delays the annihilation of dislocations and reduces the plastic instability, while the hard phase in the planar uneven structure suppresses the crack initiation, and the soft phase delays the crack propagation.

show abstract

Fracture mechanism of AZ31 magnesium alloy processed by equal channel angular pressing comparing three point bending test and tensile test

Cited by 24 publications

References 45 publications

Study of Static Flexural Strength Anisotropy of Yttrium Calcium Oxyborate Crystals

Study of Static Flexural Strength Anisotropy of Yttrium Calcium Oxyborate Crystals

Effect of thermomechanical processing defects on fatigue and fracture behaviour of forged magnesium

Improving mechanical properties for pure irons by local surface mechanical attrition treatment

Contact Info

Product

Resources

About