Effects of Fe and Si impurities on tensile elongation of Al-Mg alloy sheets.

Effects of Fe and Si as impurities on tensile elongation were investigated in Al–5.5%Mg alloys used for automobile body-panel sheets. Constituent particles content of AlnFe and Mg2Si is increased by the increase of Fe and Si content respectively. Effect of Fe content on elongation strongly depends on the direction of tensile testing. Elongation decreases in longitudinal and 45° directions, but increases in transverse direction with Fe content. This is due to texture change to more random orientation. Average elongation over three directions, (ElL+2ElD + ElC)/4, is decreased slightly with Fe content, which is regarded as due to the grain refinement by AlnFe pinning. On the other hand, elongation is decreased in all directions with increase in Si content, and the decrease in average elongation is much larger than the case of Fe addition. Acceleration in void formation around Mg2Si particles during the last stage of tensile testing is responsible for the higher deteriorating effect of Si.