Hydrogen embrittlement and strain rate sensitivity of electrodeposited copper: part I - the effect of hydrogen content

Slow strain rate tensile testing was conducted on electrodeposited copper, which is a candidate coating material for used nuclear fuel containers. Embrittlement was observed in electrodeposited copper containing 26.4 +/- 1.0 ppm hydrogen, with a strain rate sensitivity such that the embrittlement was exacerbated at lower strain rate (5 x 10-7 s-1). Tensile tests conducted at 100 degrees and 200 degrees C also intensified embrittlement when compared with tests conducted at room temperature. In contrast, electrodeposited copper containing only 5.25 +/- 0.97 ppm hydrogen exhibited ductile behavior at all tested strain rates and temperatures. These findings suggest that a previously unexplained slow strain rate hydrogen embrittlement can operate in electrodeposited copper provided that the hydrogen concentration is sufficiently high. Further analyses revealed that the deformation of embrittled copper is achieved by the formation of internal microcracks which coalesce at the point of failure.