Investigation of galvanic corrosion in laser-welded stainless steel sheets

Chi-Tat Kwok; Siu Lung Fong; Fai Tsun Cheng; Hau-Chung Man

doi:10.1117/12.596319

8 October 2004 Investigation of galvanic corrosion in laser-welded stainless steel sheets

Chi-Tat Kwok, Siu Lung Fong, Fai Tsun Cheng, Hau-Chung Man

Proceedings Volume 5662, Fifth International Symposium on Laser Precision Microfabrication; (2004) https://doi.org/10.1117/12.596319
Event: Fifth International Symposium on Laser Precision Microfabrication, 2004, Nara, Japan

Abstract

In the present study, bead-on-plate specimens of 1-mm sheets of austenitic and duplex stainless steels were fabricated by laser penetration welding with a 2.5-kW CW Nd:YAG laser. The galvanic corrosion behavior of laser-weldment (LW) against as-received (AR) specimens with an area rato of 1:1 in 3.5% NaCL solution was studied by means of a zero-resistance ammeter. The free corrosion potentials of as-received specimens were found to be considerably higher than those of laser weldments, indicating that the weldments are more active and always act as anodes. The ranking of galvanic current densities (I_G) of the couples in ascending order is: AR S31603-LW S31603 < AR S31803-LW S31803 < AR S32760-LW S32760 < AR S30400-LW S30400. For the galvanic couple between AR S30400 and LW S30400, the I_G is the highest (78.6 nA/cm²) because large amount of δ-ferrite in the weld zone acts as active sites. On the other hand, the I_G of the galvanic couple between AR S31603 and LW S31603 is the lowest (-26 nA/cm²) because no δ-ferrite is present after laser welding. The recorded I_G of all couples revealed constantly low values (in the rnage of nA/cm²) and sometimes stayed negative, which indicated polarity reversal.

Citation Download Citation

Chi-Tat Kwok, Siu Lung Fong, Fai Tsun Cheng, and Hau-Chung Man "Investigation of galvanic corrosion in laser-welded stainless steel sheets", Proc. SPIE 5662, Fifth International Symposium on Laser Precision Microfabrication, (8 October 2004); https://doi.org/10.1117/12.596319

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