Role of Double Oxide Film Defects in the Formation of Gas Porosity in Commercial Purity and Sr-containing Al Alloys

Farhoodi, Batool; Raiszadeh, Ramin; Ghanaatian, Mohammad-Hasan

doi:10.1016/j.jmst.2013.09.001

Cited by 33 publications

(20 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nateghian [24] suggested that, with the addition of 0.05 wt pct Sr to commercial purity aluminum, the Al 2 O 3 layer started to transform into SrO. Farhoodi et al [25] suggested that such a transformation might make a bifilm defect stronger which would produce less rupture points and thus the entrapped atmosphere was less likely to be consumed. In this case, a bifilm defect should last longer in an aluminum melt containing Sr (and contribute to increased porosity in the aluminum castings).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Sr Modifier Additions on Double Oxide Film Defects in 2L99 Alloy Castings

Chen

Griffiths

2017

Metall Mater Trans A

View full text Add to dashboard Cite

In this paper, Sr modifier (300 ppm) was added to 2L99 alloy sand castings to investigate its effect on bifilm defects in the castings. Two different sand molds were used in this study, with good and bad running system designs, to introduce different amounts of bifilm defects into the castings. The mechanical properties of the modified 2L99 castings were compared to the properties of unmodified castings and showed that with high bifilm defect contents (H) the Sr addition reduced the Weibull modulus of the UTS by 67 pct and the Position Parameter by 5 pct, and introduced a bimodal distribution into the Weibull plot of the pct Elongation. However, for castings with low bifilm defect content (L), the Weibull moduli of both the UTS and pct Elongation were significantly improved (by 78 and 73 pct, respectively) with the addition of Sr. The Position Parameter of the pct Elongation was improved by 135 pct. The results suggested that a desirable modification effect can only be achieved while the bifilm defect content in a casting was low.

show abstract

Section: Introductionmentioning

confidence: 99%

The Effect of Sr Modifier Additions on Double Oxide Film Defects in 2L99 Alloy Castings

Chen

Griffiths

2017

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…The increase in the Al 4 Sr volume fraction increases the overall porosity area of the gas pores from 6.2% to 9.6%, compared with the sample without Sr. This porosity decreases both the yield and ultimate tensile strength values of the produced samples, as Tekman et al have reported [28,29]. Porosity parameters, namely, the total porosity area is analyzed using Pixcavator IA 4.3 software (Marshall University, Huntington, WV, USA).…”

Section: Resultsmentioning

confidence: 99%

Effect of a Minor Sr Modifier on the Microstructures and Mechanical Properties of 7075 T6 Al Alloys

Sun

Wang

et al. 2017

Metals

View full text Add to dashboard Cite

Abstract:The influence of a minor strontium (Sr) modifier on the microstructures and mechanical properties of 7075 Al alloys was investigated in this paper. The grain size of cast 7075 Al alloys was refined from 157 µm to 115 µm, 108 µm, and 105 µm after adding 0.05 wt. %, 0.1 wt. %, and 0.2 wt. % Sr, respectively. The extruded 7075 Al alloys was refined with different degrees of Sr modifier. The mechanical properties were optimum when adding 0.1 wt. % Sr. The ultimate tensile strength (σ b ) increased from 573 to 598 MPa and the elongation-to-failure (δ f ) was raised from 19.5% to 24.9%. The microhardness increased from 182 to 195 Hv. The tensile fracture surface via scanning electron microscopy (SEM) revealed a transition from brittle fracture to ductile fracture as Sr increased from 0 wt. % to 0.2 wt. %. The result in this paper proved that the modifier can improve the properties of 7075 Al alloy.

show abstract

“…Another possible explanation for the formation of the hollow area is the flotation of real double oxide film defects that were present in the lower bar, which expanded due to the diffusion of hydrogen into their atmospheres, [16][17][18] to be accumulated underneath the oxide layer at the top of the lower bar (named 'oxide layer 1' in Fig. 1).…”

Section: Discussionmentioning

confidence: 99%

“…1). The rate of flotation of oxide layers is known [16][17][18] to depend on the hydrogen content of the melt, which in turn depends on the rate of reaction of the melt with ambient moisture. As the Mg content of the melt increased, this reaction rate increased; 19 therefore, the hydrogen content of the melt and the rate of the flotation of the oxide films, and hence the possibility of the formation of the hollow area underneath the oxide layer, increased.…”

Section: Discussionmentioning

confidence: 99%

Study of double oxide film defect behaviour in liquid Al–Mg alloys

Amirinejhad

Raiszadeh

Doostmohammadi

2013

International Journal of Cast Metals Research

View full text Add to dashboard Cite

The change in the composition of oxide layers and the possibility of the formation of bonding between the layers of a double oxide film defect when held in Al melts containing 0?7, 1 and 2 wt-%Mg were investigated. The defect was modelled by maintaining two aluminium oxide layers in contact with one another in the melt at 1023 K for times between 5 s and 50 h. Any changes in the composition and morphology of these layers were studied by SEM and energy dispersive X-ray. The results showed that in all the alloys, the initial Al 2 O 3 layer first transformed to MgAl 2 O 4 and then to MgO. These transformations caused the two layers to bond together gradually. The results confirmed that, in all the Al alloys containing 0?3-4?5 wt-%Mg, oxide films have the chance to heal if held in the liquid metal for a long enough period of time.

show abstract

Role of Double Oxide Film Defects in the Formation of Gas Porosity in Commercial Purity and Sr-containing Al Alloys

Cited by 33 publications

References 17 publications

The Effect of Sr Modifier Additions on Double Oxide Film Defects in 2L99 Alloy Castings

The Effect of Sr Modifier Additions on Double Oxide Film Defects in 2L99 Alloy Castings

Effect of a Minor Sr Modifier on the Microstructures and Mechanical Properties of 7075 T6 Al Alloys

Study of double oxide film defect behaviour in liquid Al–Mg alloys

Contact Info

Product

Resources

About