Effect of microporosity on the tensile properties of AZ91 magnesium alloy

The stress field of magnesium alloy AZ80 billets at different start-up levels in direct-chill (DC) casting is calculated, including equivalent stresses, equivalent strains, sump depth, and temperature fields. The equivalent stresses and strains are highest in the center of the billet for all start-up levels considered. A new criterion called cracking damage index (CDI) is used to predict the cracking susceptibility of the billets. At dangerous position of the billets, increasing start-up levels is benefit for the decrease of CDI, equivalent stresses, and equivalent strains. Consequently, reasonably increasing start-up levels can reduce the risk of cracks in the billets.

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“…The strain-rate-sensitivity coefficient m is shown in Figure 2d, drawn from the results of some researches on AZ91 alloy. [9][10][11][12][13] …”

Section: Thermophysical and Mechanical Propertiesmentioning

confidence: 99%

Effect of Start‐Up Levels on the Stress–Strain Field and Cracking Tendency during Direct‐Chill Casting of Magnesium Alloy AZ80

Bai

Wei

et al. 2016

Adv Eng Mater

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“…The strain-rate-sensitivity coefficient, m, variation with temperature was estimated by fitting a straight line to values obtained from the literature, [12,13,16,18,19] as shown in Figure 7. The same variation was used for both binary alloys of the present study, even though the data points are all for AZ91.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…Some of the data were determined from stress-strain curves at various temperatures and strain rates, [12,13,16] while others are directly reported values. [18,19] Room-temperature values for the strain hardening coefficient, n, were determined by fitting the as-cast binary Mg-Al alloy stress-strain curves of Cao and Wessen [17] to Eq. [8] (with m = 0).…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…Some studies have been identified that report suitable measurements of mechanical properties of as-cast magnesium alloys at room and elevated temperatures. [12][13][14][15][16][17][18][19][20] However, the data in References 12 through 20 are also not sufficient for stress modeling of casting. In this study, force measurements from specially designed casting experiments are used to calibrate a viscoplastic constitutive model for Mg-Al alloys.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Stresses during Casting of Binary Magnesium-Aluminum Alloys

Pokorný

Monroe

Beckermann

et al. 2010

Metall Mater Trans A

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A viscoplastic stress model is used to predict contraction forces measured during casting of two binary Mg-Al alloys. Force measurements from castings that did not hot tear, together with estimates from data found in the literature, are used to obtain the high-temperature mechanical properties needed in the stress model. In the absence of hot tearing, the simulation results show reasonably good agreement with the measurements. It is found that coherency of the semisolid mush starts at a solid fraction of about 0.5 and that the maximum tensile strength for the Mg-1 and 9 wt pct Al alloys at their final solidification temperatures is 1.5 and 4 MPa, respectively. In the presence of hot tearing, the measured stresses are generally overpredicted, which is attributed to the lack of a fracture model for the mush. Based on the comparison of measured and predicted stresses, it is also shown that coupling of the stress model to feeding flow and macrosegregation calculations is needed in order to accurately predict stresses in the presence of hot tearing.

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“…Hence, the degradation in mechanical properties including tensile strength [4,5], elongation (e F ) [6][7][8][9], fracture toughness as well as fatigue life (N f ) [10] is directly related to the structural quality of castings.…”

Section: Introductionmentioning

confidence: 99%

On the Relationship between Structural Quality Index and Fatigue Life Distributions in Aluminum Aerospace Castings

Özdeş¹,

Tiryakioğlu²

2016

Metals

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Abstract:Tensile and fatigue testing results of D357 and B201 aluminum alloy aerospace castings reported in the literature have been reanalyzed. Yield strength-elongation bivariate data have been used as a measure of the structural quality of castings, and converted into quality index. These results as well as fatigue data have been analyzed by using Weibull statistics. A distinct relationship has been observed between expected fatigue life and quality index. Moreover, probability of survival in fatigue life was found to be directly linked to the proportions of the quality index distributions in two different regions, providing further evidence about the strong relationship between elongation, i.e., structural quality and fatigue performance.

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Effect of microporosity on the tensile properties of AZ91 magnesium alloy

Cited by 45 publications

References 17 publications

Effect of Start‐Up Levels on the Stress–Strain Field and Cracking Tendency during Direct‐Chill Casting of Magnesium Alloy AZ80

Effect of Start‐Up Levels on the Stress–Strain Field and Cracking Tendency during Direct‐Chill Casting of Magnesium Alloy AZ80

Simulation of Stresses during Casting of Binary Magnesium-Aluminum Alloys

On the Relationship between Structural Quality Index and Fatigue Life Distributions in Aluminum Aerospace Castings

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