Online (passive) thermographic inspection of overlap joints of aluminium and zinc coated steel sheets made by cold metal transfer weld brazing process was explored. Different experimental trials were conducted for demonstrating the feasibility of thermographic inspection to detect the porosities, improper weld bead and to differentiate the pre weld temperature. The whole process was monitored using infrared cameras in different wavelength region. Image analysis algorithms were developed to reconstruct the thermal images that contain the signatures of the weld defects and to extract the pre weld temperature and its evolution with distance from the centre of the weld torch. Post-weld radiography lends strong support to the observations. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

Krishnan Balasubramaniam

Department of Mechanical Engineering

Prabhu Rajagopal

K. Renil Thomas

Sreedhar Unnikrishnakurup

Laser Beam Welding

Partial discharges

THERMOGRAPHY (IMAGING)

Welds

ZINC COATINGS

COLD METAL TRANSFERS

DISSIMILAR JOINTS

EXPERIMENTAL TRIALS

Image analysis algorithms

Infra-red cameras

Online monitoring

WAVELENGTH REGIONS

ZINC COATED STEEL SHEET

Nondestructive examination

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Online monitoring of cold metal transfer (CMT) process using infrared thermography

Quantitative InfraRed Thermography Journal

The effect of zinc coating on the weld brazability of dissimilar Al–steel joint made by the cold metal transfer (CMT) process using the passive infrared (IR) thermography sensing technique was investigated using a numerical model. The numerical model was developed to understand the heat transfer phenomena during the CMT process. In the developed model, a thin thermally resistive layer (TTRL) was introduced at the interface of the two joining metals in order to manipulate the absence of zinc deposition on the steel sheet. The model could clearly identify the lack of weld deposition. The results were compared with experimental observations. Two cases are considered in this paper. The first study identifies the sensitivity of the IR thermography technique and the second one reveals the resolution in defect detection. The developed 3D model can be used as a tool to identify the defects caused during welding and can provide insights into the online monitoring of cold metal transfer joining process. © 2019, Springer-Verlag London Ltd., part of Springer Nature.

International Journal of Advanced Manufacturing Technology

Numerical model and experimental validation for online monitoring of cold metal transfer joining of aluminium to galvanized steel

Online weld-monitoring systems are being developed to reduce the cost and delays in detecting defects and rectifying welding parameters. It is known that variations (a) in arc positioning, (b) in heat input and (c) due to the presence of contaminants distinctly manifest as differences in the spatial and temporal surface temperature distributions. In this paper, it is demonstrated that (i) offset positioned thermal imaging of online TIG welding is a feasible non-destructive monitoring technique for detecting porosities in the AA2219 welding, (ii) spatio-temporal temperature distributions close to and in the vicinity of the weld pool can provide statistically distinct features in defect-free and defective weld regions, and (iii) thermal image-based assessment compares very favorably with post-weld radiography assessment for significant defect occurrence. Given the high frame rates and temperature resolution of currently available infrared cameras, it is believed that infrared thermography can be a practical weld-monitoring option capable of providing reliable assessment comparable to more elaborate off-line assessment. © 2012 Elsevier B.V. All rights reserved.

Journal of Materials Processing Technology

Automatic defect identification using thermal image analysis for online weld quality monitoring

Journal of Manufacturing Science and Engineering

Cold Metal Transfer Joining of Aluminum AA6061-T6-to-Galvanized Boron Steel

Dissimilar metal joining of aluminum alloy to galvanized steel with Al–Si, Al–Cu, Al–Si–Cu and Zn–Al filler wires

Materials & Design

The CMT short-circuiting metal transfer process and its use in thin aluminium sheets welding

Materials Science and Engineering: A

Suppression of intermetallic reaction layer formation by controlling heat flow in dissimilar joining of steel and aluminum alloy

Journal	Data powered by TypesetQuantitative InfraRed Thermography Journal
Publisher	Data powered by TypesetTaylor and Francis Ltd.
ISSN	17686733
Open Access	No