Environmental embrittlement of Al-Mg-Si base alloys deformed at low strain rates in laboratory air.

Abstract

Two medium-strength Al Mg Si alloys exhibited environmental embrittlement when deformed in laboratory air at low strain rates. Tensile specimens prepared from hot rolled plates of Al 0.75Mg 0.75Si and Al 0.75Mg 0.75Si 0.35Cu alloys were solution treated for 1 h at 540°C, quenched in water and aged for 30 min at 175°C. They were deformed in tension at initial strain rates ranging from 1.7×10-7 to 8.3×10-4 s-1 in a laboratory air with a relative humidity of 40 80. Both alloys showed ductile transgranular fracture when tested at a strain rate of 8.3×10-4 s-1 , however, they exhibited intergranular embrittlement with lower tensile elongation and reduction in area when tested at a strain rate of 1.7×10-7 s-1. This tendency of intergranular embrittlement is prominent in the Al 0.75Mg 0.75Si 0.35Cu alloy and the eŠect of hydrogen absorbed from the test environment on such embrittlement was studied using deuterium as a tracer of hydrogen.

Hydrogen Evolution Behavior in an Al-Mg-Si Alloy Affected by Hydrogen Embrittlement

“…However, little is know about the effect of atmospheric hydrogen on the mechanical properties of the Al-Mg-Si alloy. Recently, age-hardened Al-Mg-Si alloys are reported to show environmental embrittlement when the alloys are tested at a slow strain rate (10 -7 s -1 ) in laboratory air [1,2]. It is believed that the phenomenon is closely related to hydrogen embrittlement.…”

Contribution of Hydrogen Embrittlement to SCC Process in Excess Si Type Al-Mg-Si Alloys

“…[3][4][5] A probable embrittlement in hydrogen environments has been also reported. 6) Then it becomes an important issue to evaluate the properties with respect to SCC and hydrogen embrittlement (HE) for the sake of securing the reliability.…”