한국주조공학회

In this study, the extruded Al-6.3Zn-2.4Mg alloys were selected among the 7000 series aluminum alloys sensitive to hydrogen environment in order to examine the effects of both the aging conditions and the length of hydrogen charging period on the the mechanical properties of the alloy. The specimens were aged for 24hours at 100oC (under aging (UA)), 120oC (peak aging (PA)), and 160oC (over aging (OA)), respectively. Charging tests were performed at RT for 12, 24, 36 hours under potentiostatic conditions (−2000 mV vs (Ag/AgCl)) for 12, 24 and 36 hours in 1M H2SO4 and 0.1%NH4SCN solution. The fracture surface was examined by scanning electron microscopy (SEM). X-ray diffraction (XRD) pattern in peak aged sample was obtained before and after hydrogen charging from extruded Al-6.3Zn-2.4Mg alloys. The decreasing rate of tensile strength and elongation is represented in order of over aging < under aging < peak aging, and it is believed that the hydrogen recharge is more sensitive to elongation than tensile strength. The formation of AlH3 in hydrogen charged Al-6.3Zn-2.4Mg alloys has been confirmed by X-ray diffraction studies.

Al-6.3Zn-2.4Mg alloy, Hydrogen embrittlement, Hydrogen attack, Temper embrittlement