Mechanical properties and precipitation evolution behavior of V-5Cr-5Ti alloy after cold rolling

- Precipitation evolution behavior of cold-rolled V-5Cr-5Ti alloy was investigated.
- There are two kinds of HCP structure precipitates in cold-rolled V-5Cr-5Ti alloy.
- The precipitates were broken into small spherical particles during cold rolling.
- The stable precipitates with FCC structure were formed after annealing.

The mechanical properties and precipitation behavior of V-5Cr-5Ti alloy were investigated after 80% cold rolling and annealing by optical microscopy, scanning electron microscopy, transmission electron microscopy (TEM), and tensile testing. The TEM analysis revealed that the cold-rolled V-5Cr-5Ti alloy had two kinds of precipitates with an hexagonal close-packed(HCP) structure. The rectangular precipitate had the following lattice parameters: a = 0.3041-0.3048 nm, c = 0.5153-0.5158 nm, and c/a = 1.69. The elliptically shaped precipitate had the following lattice parameters: a = 0.3080-0.3082 nm, c = 0.5003-0.5009 nm, and c/a = 1.62. The other precipitates had a face-centered cubic(FCC) structure. The precipitates were broken into small spherical particles, which were arranged in the vicinity of the band structure. After annealing (1273 K × 1 h), the stable precipitates were formed by increasing the components of Cr and N. The yield strength of cold-rolled V-5Cr-5Ti alloy after annealing was 21.5% higher than that before cold rolling, and the yield ratio increased from 0.69 to 0.79.