The effect of double pass GMAW process on microstructure and mechanical properties of AA 6061-T6 joining plates

S. R S Bakar, M. Y. Ahmad, M. F A Ibrahim, Azman Jalar @ Jalil, S. J S Djalil, Norinsan Kamil Othman

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

This paper presents an investigation on microstructure and mechanical properties of welded AA 6061-T6 plate using filler metal ER 4043 in the Gas Metal Arc Welding (GMAW) process. Double pass welding technique on both sides of 5 mm thick plate or more is required to provide sufficient weld pool in the joint. The weld metal of the first welding pass exhibits finer microstructure than the second welding pass. The size of Mg 2Si precipitations in the heat-affected zone (HAZ) region is larger than in the base metal due to the welding process that reheats the alloy from the T6 condition above the eutectic temperature. Rapid cooling of the first pass and moderate cooling rate for the second pass during weld metal solidification eventually resulted in significantly change the shape and size in the microstructure that had affected the hardness and mechanical properties. Comparisons made to the base metal on the hardness test results found that the hardness of first pass weld metal dropped by 15%, and by 37.5% for the second weld metal, while the hardness at the boundaries of the first and second weld metals dropped by 32.5%. The ultimate tensile strength and strain of the weld joint with ER 4043 also decreased by 48% and 94% respectively. Based on the findings of the study, it is concluded that even though the double sided welding technique is able to overcome shallow weld penetration to avoid stress concentration that leads to the fatigue failure, the metallurgical changes eventually contributes to degradation of mechanical properties.

Original languageEnglish
Title of host publicationKey Engineering Materials
Pages98-104
Number of pages7
Volume510-511
Edition1
DOIs
Publication statusPublished - 2012
Event12th International Symposium on Advanced Materials, ISAM-2011 - Islamabad
Duration: 26 Sep 201130 Sep 2011

Publication series

NameKey Engineering Materials
Number1
Volume510-511
ISSN (Print)10139826

Other

Other12th International Symposium on Advanced Materials, ISAM-2011
CityIslamabad
Period26/9/1130/9/11

Fingerprint

Gas metal arc welding
Joining
Welds
Metals
Mechanical properties
Microstructure
Welding
Hardness
Cooling
Filler metals
Tensile strain
Heat affected zone
Eutectics
Solidification
Stress concentration
Tensile strength
Fatigue of materials
Degradation

Keywords

  • GMAW
  • Hardness
  • Microstructure
  • Tensile strength

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Bakar, S. R. S., Ahmad, M. Y., Ibrahim, M. F. A., Jalar @ Jalil, A., Djalil, S. J. S., & Othman, N. K. (2012). The effect of double pass GMAW process on microstructure and mechanical properties of AA 6061-T6 joining plates. In Key Engineering Materials (1 ed., Vol. 510-511, pp. 98-104). (Key Engineering Materials; Vol. 510-511, No. 1). https://doi.org/10.4028/www.scientific.net/KEM.510-511.98

The effect of double pass GMAW process on microstructure and mechanical properties of AA 6061-T6 joining plates. / Bakar, S. R S; Ahmad, M. Y.; Ibrahim, M. F A; Jalar @ Jalil, Azman; Djalil, S. J S; Othman, Norinsan Kamil.

Key Engineering Materials. Vol. 510-511 1. ed. 2012. p. 98-104 (Key Engineering Materials; Vol. 510-511, No. 1).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Bakar, SRS, Ahmad, MY, Ibrahim, MFA, Jalar @ Jalil, A, Djalil, SJS & Othman, NK 2012, The effect of double pass GMAW process on microstructure and mechanical properties of AA 6061-T6 joining plates. in Key Engineering Materials. 1 edn, vol. 510-511, Key Engineering Materials, no. 1, vol. 510-511, pp. 98-104, 12th International Symposium on Advanced Materials, ISAM-2011, Islamabad, 26/9/11. https://doi.org/10.4028/www.scientific.net/KEM.510-511.98
Bakar SRS, Ahmad MY, Ibrahim MFA, Jalar @ Jalil A, Djalil SJS, Othman NK. The effect of double pass GMAW process on microstructure and mechanical properties of AA 6061-T6 joining plates. In Key Engineering Materials. 1 ed. Vol. 510-511. 2012. p. 98-104. (Key Engineering Materials; 1). https://doi.org/10.4028/www.scientific.net/KEM.510-511.98
Bakar, S. R S ; Ahmad, M. Y. ; Ibrahim, M. F A ; Jalar @ Jalil, Azman ; Djalil, S. J S ; Othman, Norinsan Kamil. / The effect of double pass GMAW process on microstructure and mechanical properties of AA 6061-T6 joining plates. Key Engineering Materials. Vol. 510-511 1. ed. 2012. pp. 98-104 (Key Engineering Materials; 1).
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AB - This paper presents an investigation on microstructure and mechanical properties of welded AA 6061-T6 plate using filler metal ER 4043 in the Gas Metal Arc Welding (GMAW) process. Double pass welding technique on both sides of 5 mm thick plate or more is required to provide sufficient weld pool in the joint. The weld metal of the first welding pass exhibits finer microstructure than the second welding pass. The size of Mg 2Si precipitations in the heat-affected zone (HAZ) region is larger than in the base metal due to the welding process that reheats the alloy from the T6 condition above the eutectic temperature. Rapid cooling of the first pass and moderate cooling rate for the second pass during weld metal solidification eventually resulted in significantly change the shape and size in the microstructure that had affected the hardness and mechanical properties. Comparisons made to the base metal on the hardness test results found that the hardness of first pass weld metal dropped by 15%, and by 37.5% for the second weld metal, while the hardness at the boundaries of the first and second weld metals dropped by 32.5%. The ultimate tensile strength and strain of the weld joint with ER 4043 also decreased by 48% and 94% respectively. Based on the findings of the study, it is concluded that even though the double sided welding technique is able to overcome shallow weld penetration to avoid stress concentration that leads to the fatigue failure, the metallurgical changes eventually contributes to degradation of mechanical properties.

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