Abstract
In recent years, saving energy of transport equipment is demanded from the viewpoint of solving environmental problems such as global warming and depletion of fossil fuel resources. To fulfil this demand, applying a promising lightweight structural material for next generation to transport equipment such as railway vehicles is expected. Thus, flame-resistant magnesium alloys are paid attention to. However, in the previous study, hydrogen embrittlement was found to occur in flame-resistant newly developed AZX 811 and commercially available AZX 611 magnesium alloys by means of slow strain rate technique tensile test in humid air environment. In the slow strain rate technique tensile test, after a crack becomes of a certain size, stress will concentrate at the crack tip and then the local strain rate will sharply increase. This will cause insufficient supply of hydrogen to the crack tip. Therefore, extent of hydrogen embrittlement may not be assessed accurately by means of the slow strain rate technique tensile test. In the present study, we have adopted humid gas stress corrosion cracking test, and assessed the extent of hydrogen embrittlement of the two flameresistant magnesium alloys by means of humid gas stress corrosion cracking test, where a certain stress intensity factor is loaded for long term in humid air environment. The load has also been applied in dry air environment to examine fundamentally the resistance to humid gas stress corrosion cracking in these alloys.
