Hot tearing criteria evaluation for direct-chill casting of an Al-4.5 pct Cu alloy

Suyitno, Suyitno; Kool, W. H.; Katgerman, L.

doi:10.1007/s11661-005-0245-6

Cited by 117 publications

(76 citation statements)

References 12 publications

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“…Such a criterion is equivalent to the RDG approach, [4] which is known to be very efficient in DC casting situations. [29] The RDG criterion does, indeed, consider a strain rate that is perpendicular to the thermal gradient. This situation is actually encountered in actual DC casting experiments, but not in tensile tests such as the one investigated here.…”

Section: Discussionmentioning

confidence: 99%

Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

Mathier

Vernède²,

Jarry³

et al. 2009

Metall Mater Trans A

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Hot tearing formation in both a classical tensile test and during direct chill (DC) casting of aluminum alloys has been modeled using a semicoupled, two-phase approach. Following a thermal calculation, the deformation of the mushy solid is computed using a compressive rheological model that neglects the pressure of the intergranular liquid. The nonzero expansion/ compression of the solid and the solidification shrinkage are then introduced as source terms for the calculation of the pressure drop and pore formation in the liquid phase. A comparison between the simulation results and experimental data permits a detailed understanding of the specific conditions under which hot tears form under given conditions. It is shown that the failure modes can be quite different for these two experiments and that, as a consequence, the appropriate hot tearing criterion may differ. It is foreseen that a fully predictive theoretical tool could be obtained by coupling such a model with a granular approach. These two techniques do, indeed, permit coverage of the range of the length scales and the physical phenomena involved in hot tearing.

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Section: Discussionmentioning

confidence: 99%

Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

Mathier

Vernède²,

Jarry³

et al. 2009

Metall Mater Trans A

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“…A large-freezing-range alloy promotes hot tearing given that such an alloy is for a longer time in a vulne- 10 . The strains and strain rates in the mushy zone increase if the cooling rate increases at the solid fraction equal to 0.95 in the center of the billet, which is plotted for three casting velocities and for different panel positions.…”

Section: Water Removalmentioning

confidence: 99%

Modeling of water removal in direct-chill casting of aluminum-alloy billets

Meysami¹,

Mahmoudi²,

Hajisafari³

2017

Mater. Tehnol.

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Water removal is one of the methods for preventing hot tears in the production of defect-free aluminum billets. Using this method, the cooling rate near the bottom of the sump is reduced, and as a result, the possibility of creating hot tears at the final stages of solidification can be minimized. The temperature of the solid crust can be increased and the residual stresses in a casting can be minimized. A system of direct-chill casting was simulated and the influence of effective parameters, like the casting speed, was investigated. The casting speed and the position of water removal were the most effective parameters. Their optimum amounts for various diameters of the aluminum alloy were critical for the accumulated residual stresses and casting condition. The optimum conditions such as the minimum sump depth, mushy-zone thickness, minimum radial thermal gradient and strain rate near the bottom of the sump were predicted by this simulation. Keywords: casting, aluminum alloy, hot crack V pri~ujo~em~lanku avtorji obravnavajo vertikalno kontinuirno (konti) litje gredic na osnovi Al zlitin z direktnim vodnim hlajenjem (angl.: Direct-Chill casting; DC). Primerna kontrola ohlajanja oz. omejevanje pretoka vode je ena izmed metod, ki prepre~uje nastanek vro~ih razpok in drugih livarskih napak med konti litjem gredic. Pri tej metodi zmanj{amo hitrost pretoka vode oz. ohlajanja na dnu zbiralnika in posledi~no zmanj{amo na minimum tudi mo`nost tvorbe vro~ih razpok v zadnji fazi strjevanja. Na ta na~in je temperatura strjenega dela ingota (gredice) oz. trdne skorje vi{ja in zaostale napetosti v gredici, nastale med litjem so manj{e. Avtorji prispevka so izvedli simulacijo procesa DC litja in ugotavljali vpliv posameznih procesnih parametrov. Na proces litja sta najbolj vplivala hitrost litja in mesto odstranjevanja vode. Optimalne vrednosti teh dveh parametrov pri litju gredic razli~nih premerov so odolo~ilno vplivale na velikost zaostalih napetosti in ostale pogoje litja Al zlitin. S to simulacijo so avtorji dolo~ili optimalne pogoje litja, kot so minimalna globina vodnega zbiralnika, debelina testaste (ka{aste) cone, najmanj{i radialni termi~ni gradient in hitrost deformacije blizu dna zbiralnika. Klju~ne besede: konti litje gredic, aluminijeve zlitine, vro~e razpoke

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“…These criteria mainly focus on the shrinkage crack susceptibility, i.e., the potential of shrinkage crack formation, which can be classified into three main categories. First, it is non-mechanical criteria, such as Clyne and Davies' and Katgerman's criteria [9] , which are defined by the ratio of vulnerable period where shrinkage crack may develop and time available for the stress relief process where mass feeding and liquid feeding occur. Second, it is mechanical criteria, such as Prokhorov, Novikov, Sczygiol, WYSO (Won-Yeo-Vol.14 No.5 September 2017…”

mentioning

confidence: 99%

“…Seol-Oh) and CBC (Cerri-Bellet-Chastel) criteria [2,[9][10][11][12] , which stress on critical strain or strain rate in relation to the fracture strain or strain rate of the mush zone in the BTR. Finally, it is a combination of both non-mechanical and mechanical criteria, such as RDG (Rappaz-Drezet-Gremaud) and Suyitno criteria [13,14] , which investigate the pressure drop over the mush zone reaching a critical value for cavity nucleation or the microporosity exceeding a critical size.…”

mentioning

confidence: 99%

Numerical simulation of central shrinkage crack formation in a 234-t steel ingot

Yang¹,

Yueqiao²,

Shen³

et al. 2017

China Foundry

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Abstract:Central shrinkage crack is a common defect encountered in steel ingot casting. It is necessary to limit the degree of crack in case of further propagation in forging. A 234-t steel ingot was dissected to check the internal quality, and a central shrinkage crack band of 1,400 mm in height and 120 mm in width, was found at a distance of 450 mm under the riser bottom line. Then, thermo-mechanical simulation using an elasto-viscoplastic finite-element model was conducted to analyze the stress-strain evolution during ingot solidification. A new criterion considering mush mechanical property in the brittle temperature range as well as shrinkage porosity was used to identify the shrinkage crack potential, where the degree of shrinkage porosity is regarded as a probability factor using a modified sigmoid function. Different casting processes, such as pouring speed, mould preheating and riser insulation, were optimized with the simulation model. The results show that fast pouring, proper mould preheating and good riser insulation can alleviate shrinkage crack potential in the ingot center.

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Hot tearing criteria evaluation for direct-chill casting of an Al-4.5 pct Cu alloy

Cited by 117 publications

References 12 publications

Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

Modeling of water removal in direct-chill casting of aluminum-alloy billets

Numerical simulation of central shrinkage crack formation in a 234-t steel ingot

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