Characterization of intermetallics in aluminum to zinc coated interstitial free steel joining by pulsed MIG brazing for automotive application

Journal Article · Mon Feb 15 00:00:00 EST 2016 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2015.12.030· OSTI ID:22587105

Basak, Sushovan ^[1]; Das, Hrishikesh ^[1]; Shome, Mahadev ^[2]

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1. Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India)
2. Material Characterization & Joining Group, R & D, Tata Steel, Jamshedpur–831007 (India)

In order to meet the demand for lighter and more fuel efficient vehicles, a significant attempt is currently being focused toward the substitution of aluminum for steel in the car body structure. It generates vital challenge with respect to the methods of joining to be used for fabrication. However, the conventional fusion joining has its own difficulty owing to formation of the brittle intermetallic phases. In this present study AA6061-T6 of 2 mm and HIF-GA steel sheet of 1 mm thick are metal inert gas (MIG) brazed with 0.8 mm Al–5Si filler wire under three different heat inputs. The effect of the heat inputs on bead geometry, microstructure and joint properties of MIG brazed Al-steel joints were exclusively studied and characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), electron probe micro analyzer (EPMA) and high resolution transmission electron microscopy (HRTEM) assisted X-ray spectroscopy (EDS) and selective area diffraction pattern. Finally microstructures were correlated with the performance of the joint. Diffusion induced intermetallic thickness measured by FESEM image and concentration profile agreed well with the numerically calculated one. HRTEM assisted EDS study was used to identify the large size FeAl{sub 3} and small size Fe{sub 2}Al{sub 5} type intermetallic compounds at the interface. The growth of these two phases in A2 (heat input: 182 J mm{sup −1}) is attributed to the slower cooling rate with higher diffusion time (~ 61 s) along the interface in comparison to the same for A1 (heat input: 155 J mm{sup −1}) with faster cooling rate and shorter diffusion time (~ 24 s). The joint efficiency as high as 65% of steel base metal is achieved for A2 which is the optimized parameter in the present study. - Highlights: • AA 6061 and HIF-GA could be successfully joined by MIG brazing. • Intermetallics are exclusively studied and characterized by XRD, FESEM and EPMA. • Intermetallic formation by diffusion is worth considering or not. • HRTEM-EDS, SAD pattern identifies the morphologies and size of intermetallics. • A compromise concerning formation of IMC is necessary.

• OSTI ID: 22587105
• Journal Information: Materials Characterization, Vol. 112; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
77 NANOSCIENCE AND NANOTECHNOLOGY
ABSORPTION SPECTROSCOPY
ABUNDANCE
BRAZING
DIFFUSION
ELECTRON MICROPROBE ANALYSIS
ELECTRON SCANNING
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
SCANNING ELECTRON MICROSCOPY
STEELS
TRANSMISSION ELECTRON MICROSCOPY
X RADIATION
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ZINC