Shear creep of titanium aluminide phase mixtures

Shear creep, the creep under orthogonal principal stresses of opposite sign as opposed to tensile creep, of the near-gamma Ti-44.7 at.% Al-2.0 at% Nb-2.0 at% Cr alloy was investigated by a two-step electric discharge machining (EDM) technique. With an applied shear stress across the cross-section of the test piece, large plastic shear strains were observed and measured at 700 and 800 degree C, even for fully lamellar microstructures. Axial tension or compression of a helix of small helix angle created torsion plus a small amount of bending. The maximum shear stress occurred on the inner side of the coil.