Effect of Cold Rolling on Hydrogen Desorption Behavior of Al-Cu-Mg and Al-Zn-Mg Alloys after Cold Rolling

The influence of cold rolling on hydrogen desorption behavior in Al-Cu-Mg and Al-Zn-Mg alloy plates was investigated.Solution-treated plates were cold-rolled with total reductions of 0, 50, 80 and 90 %, and kept at room temperature for 168 h.Vickers hardness of the specimens increased with the rolling reduction.Thermal desorption analysis revealed that a desorption peak at about 350 in the specimen without cold rolling (0% reduction), attributable to hydrogen trapped by dislocations, changed markedly with rolling reduction: the desorption peak split into two peaks and the desorption amount of the peak at lower temperature increased notably with increasing cold reduction.To investigate the cause of this phenomenon, hardness measurement and electron backscattering diffraction analysis were carried out for the specimen 90% cold-rolled and then heated to 350 .The hardness was decreased by about 50 % by the heating, and partially recrystallized microstructure containing some recrystallized grains in the recovered matrix was observed in the heated specimen.From these results, recovery and partial recrystallization were attributable to the appearance of the low-temperature peak.The change in hydrogen desorption behavior with holding time for up to 144 h at room-temperature was also examined in the 90% cold-rolled specimens.The desorption amount corresponding to the two peaks described above stemming from hydrogen atoms trapped by dislocations decreased with the holding time at room temperature, indicating that the hydrogen atoms trapped by dislocations can be released during room-temperature holding.The whole results obtained in this study have clarified the role of deformation microstructures on desorption behavior of the hydrogen atoms trapped by dislocations.