Strength of Thixoformed A319 Alloy at Elevated Temperature

A. M. Aziz, M. Z. Omar, Z. Sajuri

Research output: Contribution to journalArticle

Abstract

Abstract: When alloys are exposed to elevated temperatures they experience a decrement in their mechanical properties that leads to material failure. However, the use of thixoforming, an alternative metal processing method, could enhance mechanical properties by minimising the defects that exist in as-received alloys. Therefore, this study aimed to determine the tensile strength of thixoformed A319 under elevated temperatures by taking into account its intended use in vehicle cylinder head components. Thixoformed A319 was compared with as-received alloy manufactured by permanent mould casting. The cooling slope method was used to prepare the feedstock for thixoforming. The feedstock was reheated by induction heating until it reached 574 °C and was then formed in a mould. Afterwards, the as-received and thixoformed samples underwent T6 heat treatment. The resulting samples were characterised by using optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray, X-ray diffraction analysis and a tensile test. Elevated temperature tensile tests were performed at 250 °C, in line with the temperature condition experienced by cylinder head components during operation. The ultimate tensile strength of the thixoformed samples was 30% higher than that of the as-received samples under elevated temperatures. Also, the analyses of the fracture surfaces showed that porosity, intermetallic compounds and impurities were amongst the failure factors for both alloys. Graphic Abstract: [Figure not available: see fulltext.].

Original languageEnglish
JournalMetals and Materials International
DOIs
Publication statusAccepted/In press - 1 Jan 2020

Fingerprint

Cylinder heads
tensile tests
tensile strength
Feedstocks
Tensile strength
Temperature
Permanent mold casting
temperature
mechanical properties
induction heating
Mechanical properties
Induction heating
X ray diffraction analysis
Intermetallics
Optical microscopy
intermetallics
vehicles
heat treatment
x rays
Porosity

Keywords

  • Aluminum-alloy
  • Cylinder head
  • Fracture analysis
  • Semi-solid
  • Tensile test

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

Cite this

Strength of Thixoformed A319 Alloy at Elevated Temperature. / Aziz, A. M.; Omar, M. Z.; Sajuri, Z.

In: Metals and Materials International, 01.01.2020.

Research output: Contribution to journalArticle

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N2 - Abstract: When alloys are exposed to elevated temperatures they experience a decrement in their mechanical properties that leads to material failure. However, the use of thixoforming, an alternative metal processing method, could enhance mechanical properties by minimising the defects that exist in as-received alloys. Therefore, this study aimed to determine the tensile strength of thixoformed A319 under elevated temperatures by taking into account its intended use in vehicle cylinder head components. Thixoformed A319 was compared with as-received alloy manufactured by permanent mould casting. The cooling slope method was used to prepare the feedstock for thixoforming. The feedstock was reheated by induction heating until it reached 574 °C and was then formed in a mould. Afterwards, the as-received and thixoformed samples underwent T6 heat treatment. The resulting samples were characterised by using optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray, X-ray diffraction analysis and a tensile test. Elevated temperature tensile tests were performed at 250 °C, in line with the temperature condition experienced by cylinder head components during operation. The ultimate tensile strength of the thixoformed samples was 30% higher than that of the as-received samples under elevated temperatures. Also, the analyses of the fracture surfaces showed that porosity, intermetallic compounds and impurities were amongst the failure factors for both alloys. Graphic Abstract: [Figure not available: see fulltext.].

AB - Abstract: When alloys are exposed to elevated temperatures they experience a decrement in their mechanical properties that leads to material failure. However, the use of thixoforming, an alternative metal processing method, could enhance mechanical properties by minimising the defects that exist in as-received alloys. Therefore, this study aimed to determine the tensile strength of thixoformed A319 under elevated temperatures by taking into account its intended use in vehicle cylinder head components. Thixoformed A319 was compared with as-received alloy manufactured by permanent mould casting. The cooling slope method was used to prepare the feedstock for thixoforming. The feedstock was reheated by induction heating until it reached 574 °C and was then formed in a mould. Afterwards, the as-received and thixoformed samples underwent T6 heat treatment. The resulting samples were characterised by using optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray, X-ray diffraction analysis and a tensile test. Elevated temperature tensile tests were performed at 250 °C, in line with the temperature condition experienced by cylinder head components during operation. The ultimate tensile strength of the thixoformed samples was 30% higher than that of the as-received samples under elevated temperatures. Also, the analyses of the fracture surfaces showed that porosity, intermetallic compounds and impurities were amongst the failure factors for both alloys. Graphic Abstract: [Figure not available: see fulltext.].

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