The Al-Mg-Si and Al-Mg-Si-Mn alloy strips with fine grains and homogeneous microstructure were prepared by the single roll melt rotating process

and the strip was prefabricated and hot extruded into densified bar at 500℃

and then it was treated by solid solution and artificial ageing treatment.The results reveal that the strip produced by the melt-spun method presents uniform structure with fine grain

and the tensile strength and yield strength of Al-Mg-Si-0.2Si alloy reach 227 MPa and 160 MPa

greatly increased compared with those of the AlMg-Si alloy

respectively

while the elongation remains above 20%.The addition of Mn can promote the formation of a new second phase MnAl

6

which is nailed to the grain boundary

hindering the migration of subcrystals during the extrusion process

and thus inhibiting the dynamic recrystallization.In addition

certain amount of Fe in β-AlFeSi phases are replaced by Mn to form β-Al（FeMn）Si

resulting in the long-needle shapeβphase transforming into lumpyα-Al

8

（FeMn）

2

Si phase

relieving the harmful effects of Fe.At T6 state

Mn-containing dispersed phase formed in Al-Mg-Si-Mn alloy can inhibit the transition from small angle grain boundary to large angle grain boundary.In addition

new grain orientation and texture deflection occurr in both alloys

however

<

111

>

texture still is remained in Al-Mg-Si-Mn alloy

which may be attributed to the inhibition of sub-grain boundary migration by Mn-containing dispersed phase in original deformed texture during recrystallization

hindering the growth of recrystallized grains.Compared with Al-Mg-Si alloy

the Al-Mg-Si-Mn alloy is preferred to maintain its original orientation under heat treatment.