Paper Title:

Galvanic Weld Metal-Base Metal Corrosion in AZ31 Magnesium Weldments

Periodical Advanced Materials Research (Volume 95)
Main Theme Corrosion, Processes and Advanced Materials in Industry
Edited by Amir Eliezer
Pages 39-42
DOI 10.4028/
Citation Carl Edward Cross et al., 2010, Advanced Materials Research, 95, 39
Online since January 2010
Authors Carl Edward Cross, P. Xu, D. Eliezer, Guy Ben-Hamu
Keywords Alloy AZ31, Galvanic Corrosion, Magnesium, Weld Zone
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Arc welds were made on wrought AZ31 magnesium plate using a variable polarity gas-tungsten arc process with AZ61 filler wire. The aluminum content of the weld metal was systematically varied using inserts pre-placed in the weld joint, machined from magnesium die-cast alloys AM20, AM50, AM60, and AZ91. When immersed in 3.5% NaCl + Mg(OH)2 solution at room temperature, pitting corrosion was found to initiate in the weld heat affected zone, spread briefly to the weld metal, and then concentrate in the base metal. Galvanic couples were examined between wrought AZ31 and die-cast alloys to further examine galvanic behavior between wrought and cast materials. Results showed that the cast material was anodic relative to the wrought material over long periods of time, unlike what was observed for weldments. Details of this study will be presented and results will be related to alloy aluminum content and the ability to passivate.