Effect of deformation band on the strength of a rolled plate of intermetallic titanium alloy based on Ti-22Al-25Nb system

The influence of deformation band (DB) in a rolled plate of VTI-4 alloy of the Ti-22Al-25Nb system on the ultimate tensile strength (UTS) of this material in tensile tests has been studied. Samples subjected to heat treatment under the same conditions differ significantly in strength: 1075 MPa for the central part of the plate and 1150 MPa for the rest of the plate volume. It is shown that the spread in strength is determined by the presence of DB and the fraction of its area in the sample cross section. The presence of DB in a sample leads to reduction in its UTS by 3-6%, when the fraction of DB in a cross section of the test samples is 30-40% by area. It is found that the central part of the plate is a monograin, which has a thickness of similar to 1 mm and orientation < 100 >(beta) along the plate principal axes. The low strength of DB material is due both to the absence of grain-boundary hardening and unfavorable crystallographic orientation of monograin relative to the tensile load. The presence of the grain and texture inhomogeneity in a rolled plate leads to incorrect results of mechanical tests and could be a potential source of a fatigue failure.

Automated summary

The study found that the presence of deformation bands in a rolled plate of VTI-4 alloy significantly affects the ultimate tensile strength of the material, with a reduction of 3-6% when the fraction of DB in the sample cross section is 30-40%. The distribution of strength in the plate is determined by the presence of DB and the fraction of its area in the sample cross section.