Effect of Secondary Coating on Weldability, Joint Performance, and Electrode Life in Resistance Seam Welding of Galvannealed Interstitial Free Steel

Autor: Nitin Kumar, Amrita Kundu, Tahsin Akhtar, Mahadev Shome, Soumyajit Koley
Rok vydání: 2021
Předmět:
Zdroj: Journal of Materials Engineering and Performance. 31:2432-2444
ISSN: 1544-1024
1059-9495
DOI: 10.1007/s11665-021-06367-y
Popis: Organosilane-based thin coating on top of galvannealed (GA) coating, known as secondary coating, provides extra protection from corrosion and thus is used for manufacturing automotive fuel tanks. In the present investigation, resistance seam weldability of 0.8-mm-thick secondary-coated GA interstitial free steel has been evaluated and compared with conventional GA sheets of identical thickness, chemistry, and mechanical properties. It has been found that the 1-3-µm-thick layer of organosilane-based secondary coating increases the electrical contact resistance by up to 50%. Consequently, the heat input increases by 34% when welding secondary coated steel as compared to conventional GA steel. This higher heat-input ensures suitable nugget formation over a wide range of parameters viz. a wider weldability lobe. This paper also addresses the test results on the service life of the welding electrodes. It has been found that the electrodes can withstand up to 30 m of continuous welding of secondary-coated steel without affecting the weld quality in terms of the joint strength. However, for conventional GA sheets, the same electrodes lay up to 20 m of welding length prior to dressing. Higher electrode face widening takes place during welding of plain GA sheets which lowers the current density and thereby affects formation of high-quality weld nugget.
Databáze: OpenAIRE
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