Effect of Heat Treatment on Hydrogen Embrittlement of Electrodeposited Copper

ABSTRACT The present work investigates the tensile behavior of a copper coating electrodeposited onto steel that had been prepared in an acid bath after heat treatment. The copper is brittle at slow strain rates (1 × 10 −6 s −1 ) but ductile at fast strain rates (1 × 10 −3 s −1 ). A uniform distribution of tiny cavities is observed throughout the material after electrodeposition. Microstructural and chemical composition characterizations demonstrate that annealing the electrodeposited copper at 600°C increases grain size and transitions the morphology adjacent to the copper‐steel deposition interface from lamellar to equiaxed. Approximately 32% of the initial 17.8 ± 4.0 wppm hydrogen content is released by the 600°C annealing. Nano‐analysis of annealed samples shows the redistribution and the coalescence of cavities at grain boundaries, twins, and dislocations. Slow strain rate (1 × 10 −6 s −1 ) tensile tests of 600°C annealed samples still show a significant strain rate sensitivity, similar to the non‐heat‐treated material, and only a small improvement in ductility. Redistribution of solute hydrogen atoms on dislocations during annealing is hypothesized to be the reason behind this phenomenon.