A study on the microstructures and mechanical properties of forged trace-boron-modified Ti-B20 alloy

Microstructure and tensile properties of a high strength metastable beta titanium alloy, Ti-B20-0.1B (wt.%), were studied. The alloy was double melted by vacuum arc melting and subsequently subjected to forging and heat treatment in the α + β phase region. The microstructural characteristics and microstructure-property relationships were investigated by solution treatment at 780 °C/740 °C and subsequent aging from 450 °C to 600 °C. The result showed that the strength of forged alloy was improved by trace boron. The strength of the alloy, which was processed by solution treatment at 780 °C and subsequent aging, was higher than that at 740 °C. Whereas, the ductility, after alloy being solution treated at high temperature, was lower than that at low temperature. Secondary α phase was precipitated incompletely. And precipitate free zone was found in the microstructure after alloy being solution treated at 740 °C followed by short-time or low-temperature aging. Secondary α phase grew with the increase of the aging temperature and aging time.