Effect of Process Parameters on Lifetime of Copper Electrodes Used In Spot Welding of IF Steel Sheets

Journal article (2016)

Authors

Hector Meneses da Costa Federal Center of Technological Education Celso Suckow da Fonseca-CEFET/RJ
J. S. Dias Federal Center of Technological Education Celso Suckow da Fonseca-CEFET/RJ
A Aguiar-Ricardo Federal Center of Technological Education Celso Suckow da Fonseca-CEFET/RJ
Rosemere de Araujo Alves Lima Federal Center of Technological Education Celso Suckow da Fonseca-CEFET/RJ
D. M. Lopes Federal Center of Technological Education Celso Suckow da Fonseca-CEFET/RJ
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Welding parameters Lifetime electrode Microhardeness Nugget Scanning electron Microscopy (SEM)
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Published Date

2016

Language

English

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Abstract

This work has a purpose to evaluate the electrode wear behaviour and the distribution of hardness in a joint welded by resistance spot welding process. The lifetime of electrodes was evaluated by examination of the electrode caps after more than 2000 points with acceptable welds. A microstructural evaluation by optical (OM) and scanning electron microscopy (SEM) was carried out. The microstructure of welded joint is primarily composed of ferrite grains. The microhardness test results indicated a significant increase in hardness in the weld nugget, probably due to the formation of martensite in the fusion zone. The hardness results for the four welding parameters selected at the end of the useful lifetime of the electrode were lower in all regions. The methodology used for parameter selection has highlighted an optimal combination of 200kgf electrodes force and 9 cy welding time (cycles), where more weld points were obtained, thereby increasing the lifetime of the electrode. The cover electrode tends to form brass (Zn + Cu) on the indentation obtained after spot welding, subsequently reducing electrode life. The results indicate the importance of combining welding parameters to reduce the electrode wear.