Elena V. Bobruk

Structure and mechanical properties of aluminum alloy 6061 subjected to equal-channel angular pressing in parallel channels

It is shown that a uniform ultrafine-grained structure in alloy 6061 can be formed already after four cycles of treatment by equal-channel angular pressing in parallel channels (ECAP-PC). Along with grain refinement, in the process of an ECAP-PC treatment there occurs in the alloy a dynamic strain aging, which results in the formation of nanodimensional particles of a strengthening phase Mg2Si. It has been established that the alloy in the UFG state demonstrates a considerably higher level of strength and better plasticity in comparison with the material after a standard strengthening treatment.

Effect of Grain Refinement on the Mechanical Behaviour of an Al6061 Alloy at Cryogenic Temperatures

A solution treated coarse grained (CG) Al6061 was subjected to high pressure torsion (HPT) at room temperature resulting in the formation of a homogeneous ultra‐fine grained (UFG) microstructure with an average grain size of 170 nm. Tensile tests were performed at room temperature (RT) and liquid nitrogen temperature (LNT). The as‐HPT UFG Al6061 alloy shows an increased strength at both RT and LNT. The decrease of testing temperature results in increased flow stress and in enhanced elongation to failure in both CG and UFG samples. The ratio σyLNT/σyRT was found to be larger for the CG Al6061 than for the UFG Al6061. Both surface relief and fracture surface observations were performed. The effect of the grain size and of the testing temperature on the mechanical behaviour of the Al6061 alloy is analyzed in detail. It is suggested that the solute atoms play an important role in the plastic deformation of the UFG Al6061 alloy.A solution treated coarse grained (CG) Al6061 was subjected to high pressure torsion (HPT) at room temperature resulting in the formation of a homogeneous ultra‐fine grained (UFG) microstructure with an average grain size of 170 nm. Tensile tests were performed at room temperature (RT) and liquid nitrogen temperature (LNT). The as‐HPT UFG Al6061 alloy shows an increased strength at both RT and LNT. The decrease of testing temperature results in increased flow stress and in enhanced elongation to failure in both CG and UFG samples. The ratio σyLNT/σyRT was found to be larger for the CG Al6061 than for the UFG Al6061. Both surface relief and fracture surface observations were performed. The effect of the grain size and of the testing temperature on the mechanical behaviour of the Al6061 alloy is analyzed in detail. It is suggested that the solute atoms play an important role in the plastic deformation of the UFG Al6061 alloy.