Hydrogen charging of Al-Mg-Si-based alloys by friction in water and its effect on tensile properties

In order to introduce high amounts of hydrogen into aluminum alloys, hydrogen charging in peak-aged AI-Mg-Si-based alloys (A6061-T6) by means of friction in water (FW) was investigated and the hydrogen embrittlement (HE) sensitivity of the samples was evaluated. Al-Mg-Si alloys containing different amounts of iron (from 0.1 to 0.7 mass %) were prepared in order to clarify the effect of iron on the HE sensitivity. Hydrogen charging was carried out by polishing the alloy surface for 1 h with a silicon carbide emery paper in water at room temperature. For comparison, hydrogen-uncharged alloy specimens were also prepared. The total amount of hydrogen in the Al-Mg-Si alloys clearly increased after the FW process, during which hydrogen was generated by the chemical reaction between water and the non-oxide coated aluminum alloys. After hydrogen charging by the FW process, the Al-Mg-Si alloy with a low iron content (0.1 mass %) showed a decrease in ductility in conventional strain rate tensile testing; conversely, alloys with higher iron contents (0.2 and 0.7 mass %) did not show a decrease in ductility. This suggests that peak-aged Al-Mg-Si alloys with high iron contents are less sensitive to HE.