Semi-solid thermal transformations in Al-Si alloys: II. The optimized tensile and fatigue properties of semi-solid 357 and modified 319 aluminum alloys

The mechanical properties of 357 and modified 319 semi-solid formed (SSM) aluminum alloys are reported. The alloys were formed from ingot that was not stirred during solidification but had undergone a semi-solid thermal transformation (SSTT) during heating to produce a spherical microstructure suitable for semi-solid forming. The T5 and T6 tensile properties were optimized for both 357 and modified 319 using various solutionizing and aging studies of formed parts. The T6 fatigue properties of both alloys were also investigated. The tensile and fatigue properties were superior to conventionally cast alloys and the properties of SSTT appear at least comparable to SSM prepared by conventional electromagnetic stirring (EM). This work is an extension of earlier work reported in this journal. (C) 2001 Elsevier Science B.V. All rights reserved.