The Effect of Grain Refinement and Cooling Rate on the Hot Tearing of Wrought Aluminium Alloys

Easton, Mark; Grandfield, John; StJohn, David H.; Rinderer, Barbara

doi:10.4028/www.scientific.net/msf.519-521.1675

Cited by 69 publications

(57 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, once a given alloy is 'sufficiently' inoculated (as discussed in section 4.2), further additions are not important with respect to the decrease in grain size and the alloy becomes less sensitive to cooling rate. Increasing the refiner amount may, however, influence the grain morphology [65,66] as discussed below.…”

Section: Grain Sizementioning

confidence: 99%

See 1 more Smart Citation

Macrosegregation in direct-chill casting of aluminium alloys

Nadella

Eskin

et al. 2008

Progress in Materials Science

248

148

View full text Add to dashboard Cite

Semi-continuous direct-chill (DC) casting holds a prominent position in commercial aluminium alloy processing, especially in production of large sized ingots.Macrosegregation, which is the non-uniform chemical composition over the length scale of a casting, is one of the major defects that occur during this process. The fact that macrosegregation is essentially unaffected by subsequent heat treatment (hence constitutes an irreversible defect) leaves us with little choice but to control it during the casting stage. Despite over a century of research in the phenomenon of macrosegregation in castings and good understanding of underlying mechanisms, the contributions of these mechanisms in the overall macrosegregation picture; and interplay between these mechanisms and the structure formation during solidification are still unclear. This review attempts to fill this gap based on the published data and own results. The following features make this review unique: results of computer simulations are used in order to separate the effects of different macrosegregation mechanisms. The issue of grain refining is specifically discussed in relation to macrosegregation. This report is structured as follows. Macrosegregation as a phenomenon is defined in the Introduction. In Part 2, direct-chill casting, the role of process parameters and the evolution of structural features in the as-cast billets are described. In Part 3, macrosegregation mechanisms are elucidated in a historical perspective and the correlation with DC casting process parameters and structural features are made. The issue of how to control macrosegregation in direct-chill casting is also dealt with in Part 3. In Part 4, the effect of grain refining on macrosegregation is introduced, the current understanding is described and the contentious issues are outlined. The review is finished with conclusion remarks and outline for the future research.

show abstract

Section: Grain Sizementioning

confidence: 99%

“…On the other hand, there are reports that the formation of very fine globular grains can increase the hot tearing susceptibility due to the limited permeability of the mushy zone [65,66].…”

Section: Grain Sizementioning

confidence: 99%

Macrosegregation in direct-chill casting of aluminium alloys

Nadella

Eskin

et al. 2008

Progress in Materials Science

248

148

View full text Add to dashboard Cite

show abstract

“…Experimentally, it has been found that although grain refinement generally increases hot tearing resistance, grain refinement below 100 lm actually increases hot tearing tendency in wrought aluminum alloys during casting. [31] Although the hot tearing strain predictions are not all that different among the three cases A, D, and E, the challenge in this area of research has been to quantitatively predict hot tearing formation in an industrially cast component. As shown in Figures 6 and 7, the inclusion of key details such as semisolid constitutive behavior that is a function of grain size is needed to capture both the macroscale and microscale aspects of this defect.…”

Section: B Effect Of Microstructure Variationsmentioning

confidence: 99%

Stress–Strain Predictions of Semisolid Al-Mg-Mn Alloys During Direct Chill Casting: Effects of Microstructure and Process Variables

Jamaly

Phillion

Drezet

2013

Metall Mater Trans B

View full text Add to dashboard Cite

The occurrence of hot tearing during the industrial direct chill (DC) casting process results in significant quality issues and a reduction in productivity. In order to investigate their occurrence, a new semisolid constitutive law (Phillion et al.) for AA5182 that takes into account cooling rate, grain size, and porosity has been incorporated within a DC casting finite element process model for round billets. A hot tearing index was calculated from the semisolid strain predictions from the model. This hot tearing index, along with semisolid stress-strain predictions from the model, was used to perform a sensitivity analysis on the relative effects of microstructural features (e.g., grain size, coalescence temperature) as well as process parameters (e.g., casting speed) on hot tearing. It was found that grain refinement plays an important role in the formation of hot cracks. In addition, the combination of slow casting speeds and a low temperature for mechanical coalescence was found to improve hot tearing resistance.

show abstract

“…4(b) due to the presence of Ti segregation when the final grain morphology is globular or spherical. Figure 5(a) compiles data 31) for the grain size and the SDAS with cooling rate for each of the alloys. The grain size data is for the alloys with only an addition of 0.005 mass% Ti as Al-3Ti-1B master alloy, i.e.…”

Section: þmentioning

confidence: 99%

Grain Morphology of As-Cast Wrought Aluminium Alloys

2011

Self Cite

View full text Add to dashboard Cite

Two of the most important microstructural features of alloys are the grain size and the secondary dendrite arm spacing (SDAS) and these two factors are shown to combine together to describe the grain morphology. Both grain refinement and the SDAS depend upon alloy composition through constitutional undercooling, but in different ways. It is shown that there is a 'characteristic' SDAS for each alloy at a particular cooling rate, and reducing the grain size causes the grain morphology to change from dendritic to cellular/rosette-like to globular or spherical. Increasing the cooling rate refines both the SDAS and the grain size, but reduces the SDAS more rapidly leading to finer, more dendritic grain structures. Particular ratios of grain size to SDAS are used to define each morphology and it is shown how these can assist with obtaining a required grain size and morphology through the use of solidification conditions and alloy chemistry.

show abstract

The Effect of Grain Refinement and Cooling Rate on the Hot Tearing of Wrought Aluminium Alloys

Cited by 69 publications

References 9 publications

Macrosegregation in direct-chill casting of aluminium alloys

Macrosegregation in direct-chill casting of aluminium alloys

Stress–Strain Predictions of Semisolid Al-Mg-Mn Alloys During Direct Chill Casting: Effects of Microstructure and Process Variables

Grain Morphology of As-Cast Wrought Aluminium Alloys

Contact Info

Product

Resources

About