On the Interpretation of Melt Quality Assessment of A356 Aluminum Alloy by the Reduced Pressure Test: The Bifilm Index and Its Physical Meaning

Uludağ, Muhammet; Çetin, Remzi; Dışpınar, Derya; Tiryakioğlu, Murat

doi:10.1007/s40962-018-0217-4

Cited by 24 publications

(13 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These oxide films might be bifilms that were generated as the Al-Mg alloys melted, and that may have provided a place for pores to straighten. This observation corroborates previous studies [13][14][15]26,27], which suggested that, at reduced pressure, pores form between the bifilms, and that BI can be used to assess melt quality.…”

Section: Bifilm Indexsupporting

confidence: 92%

See 1 more Smart Citation

Effects of Mg Content on Hydrogen Content and Melt Quality of Al-Mg Alloys

Jang

Kang

Yoon

et al. 2019

Metals

View full text Add to dashboard Cite

In Al-Mg alloys with Mg content 0 ≤ XMg ≤ 6 wt. %, the effects of XMg on dissolved hydrogen content ([H]) and melt quality were investigated. [H] was measured using the Closed-Loop Recirculation method, and the melt quality was quantified using the density index (DI), bifilm index (BI), and porosity measurement. [H] in the molten alloys increased with increasing XMg and melt temperature TMelt; these trends agree with theoretical calculations for hydrogen solubility. The tendency of melt quality vs XMg was similar in DI, BI, and porosity measurements, and the poorest melt quality was observed in the Al-4Mg alloy that had XMg = 4 wt. %, whereas the highest [H] was obtained in the Al-6Mg alloy melt that had XMg = 6 wt. % Mg. During thermogravimetric/differential thermal analysis, rapid oxidation occurred in the Al-4Mg alloy melt during the holding time between 45 and 60 min at 800 °C., i.e., just before the molten metal was cast. The inferior melt quality of Al-4Mg alloy may have been caused by high-temperature oxidation.

show abstract

Section: Bifilm Indexsupporting

confidence: 92%

“…A bifilm is a doubled-over oxide film that is caused by movement of the melt. The bifilm can trap gas; the combination of bifilm and gas may constitute the main defects in the melt [13][14][15][16][17]. The maximum length of pores has been proposed as an indication of bifilm length, and is represented as the bifilm index (BI).…”

Section: Introductionmentioning

confidence: 99%

Effects of Mg Content on Hydrogen Content and Melt Quality of Al-Mg Alloys

Jang

Kang

Yoon

et al. 2019

Metals

View full text Add to dashboard Cite

show abstract

“…48 However, RPT can be used for the characterization of the quantity of entrained bifilms present in the liquid metal. 49,50 During solidification under reduced pressure, the gas phase trapped between the oxide layers of double oxide films is expanded. Furthermore, the solubility of hydrogen in the alloy is lowered due to the reduced hydrogen partial pressure.…”

Section: Melt Quality Assessmentmentioning

confidence: 99%

The Effects of Rotary Degassing Treatments on the Melt Quality of an Al–Si Casting Alloy

et al. 2020

View full text Add to dashboard Cite

In order to produce cast components, which meet the quality requirements of the automotive and aerospace industries, the control of liquid metal quality prior to the casting process is essential. Rotary degassing is the most commonly used melt treatment method in the foundry industry, which can effectively reduce the inclusion and solute hydrogen content of the metal. This procedure is often combined with fluxing, which allows more efficient inclusion removal during melt processing. In this study, the effects of rotary degassing treatments executed with and without flux addition on the melt cleanliness were compared. The quality of the molten metal was characterized by the microscopic inspection of K-mold specimens, X-ray computed tomography of reduced pressure test samples, and by Density-Index evaluation. The inclusions found on the fracture surfaces of K-mold samples were analyzed with energy-dispersive X-ray spectroscopy. Based on the results, rotary degassing coupled with flux addition can be an effective inclusion and solute hydrogen removal technique that can significantly improve melt quality. On the other hand, rotary degassing executed without flux addition can increase the inclusion content of the melts. This can be attributed to the chemical reaction between the liquid alloy and the N 2 purging gas during the degassing process. It was also found that inclusion content highly influences the tendency to porosity formation.

show abstract

“…Bifilm index of Source A and C are close to each other which is around 50 mm. Uludag [29] had interpreted the meaning of bifilm index. According to the approach, it was indicated that any melt with bifilm index higher than 50 mm would classify as "bad quality".…”

Section: Resultsmentioning

confidence: 99%

“…Thereby the porosity was decreased since bifilms were unable to unravel. Uludag et al [26][27][28][29] studied the influence of Sr on bifilm index. It was found that addition of Sr had decreased the size and length of pores which was attributed to the healing of bifilms as was reported by Ramin [25,30,31].…”

Section: Introductionmentioning

confidence: 99%

Determination of Acceptable Quality Limit for Casting of A356 Aluminium Alloy: Supplier’s Quality Index (SQI)

Erzi

Gürsoy

Yüksel

et al. 2019

Metals

View full text Add to dashboard Cite

Aluminium and its alloys have been widely used in the automotive industry for some time and A356 is one of the most popular aluminium alloys today in the sector. It contains approximately 7 wt.% Si and 0.3 wt.% Mg. Due to the defects that may be present in the cast parts, expected mechanical properties may not be reached and this alloy may perform in service under its potential. In a low pressure die casting, several precautions have to be taken in order to produce high quality and defect-free castings. Temperature of casting and the schemical composition of the melt is recorded continuously. Die temperature, pressure levels and their durations are optimized; degassing and fluxing operations are performed. Yet, regardless of the precautions, there could still be rejected parts. It is becoming clear that a good quality raw material is one of the most underrated points of the industry and that the starting material has a great effect on the final product and it should be taken in to account more seriously. Therefore, regarding the first rule of Campbell's 10 Rules of Casting, in this study, the quality of the starting material of supply chains for a wheel manufacturer was investigated. Chemical compositions were compared, fluidity tests, mechanical tests and bifilm indexes of these various sources and ingots were measured and a final quality index was proposed to create a reference for the quantification of quality of supplier's ingots. This new index was compared with the rejection rates.

show abstract

On the Interpretation of Melt Quality Assessment of A356 Aluminum Alloy by the Reduced Pressure Test: The Bifilm Index and Its Physical Meaning

Cited by 24 publications

References 22 publications

Effects of Mg Content on Hydrogen Content and Melt Quality of Al-Mg Alloys

Effects of Mg Content on Hydrogen Content and Melt Quality of Al-Mg Alloys

The Effects of Rotary Degassing Treatments on the Melt Quality of an Al–Si Casting Alloy

Determination of Acceptable Quality Limit for Casting of A356 Aluminium Alloy: Supplier’s Quality Index (SQI)

Contact Info

Product

Resources

About