Abstract
In order to reduce the cost of titanium alloys, a novel low-cost Ti-3Al-5Mo-4Cr-2Zr-1Fe (Ti-35421) titanium alloy was developed. The influence of heat treatment on the microstructure characteristics and mechanical properties of the new alloy was investigated. The results showed that the microstructure of Ti-35421 alloy consists of a lamina primary α phase and a β phase after the solution treatment at the α + β region. After aging treatment, the secondary α phase precipitates in the β matrix. The precipitation of the secondary α phase is closely related to heat treatment parameters—the volume fraction and size of the secondary α phase increase when increasing the solution temperature or aging time. At the same solution temperature and aging time, the secondary α phase became coarser, and the fraction decreased with increasing aging temperature. When Ti-35421 alloy was solution-treated at the α + β region for 1 h with aging surpassing 8 h, the tensile strength, yield strength, elongation and reduction of the area were achieved in a range of 1172.7–1459.0 MPa, 1135.1–1355.5 MPa, 5.2–11.8%, and 7.5–32.5%, respectively. The novel low-cost Ti-35421 alloy maintains mechanical properties and reduces the cost of materials compared with Ti-3Al-5Mo-5V-4Cr-2Zr (Ti-B19) alloy.
Highlights
Titanium alloys are widely used in aerospace, biomedical, and marine engineering due to their low density, excellent mechanical properties and good corrosion resistance [1,2,3,4]
The microstructure of near-β titanium alloys can be significantly improved through heat treatment, and the microstructures have a decisive influence on the properties of these titanium alloys [16,17,18,19]
The main results are as follows: The volume fraction of the primary α phase depends on the solution temperature
Summary
Titanium alloys are widely used in aerospace, biomedical, and marine engineering due to their low density, excellent mechanical properties and good corrosion resistance [1,2,3,4]. The ultimate strength, elongation and toughness of Ti-B19 alloy are 1250 MPa, 7.7% and 70 MPa·m1/2 , respectively. To reduce the cost and maintain the mechanical properties of Ti-B19 alloy, an inexpensive Fe was added to replace the expensive V. The nominal composition of the new designed alloy is Ti-3Al-5Mo-4Cr-2Zr-1Fe. The microstructure of near-β titanium alloys can be significantly improved through heat treatment, and the microstructures have a decisive influence on the properties of these titanium alloys [16,17,18,19]. It has been reported that Ti-7333 alloy [21] and Ti-5321 alloy [14] undergo reasonable heat treatment; both alloys can obtain excellent microstructure and mechanical properties. Different heat treatments were chosen to examine the evolution of the microstructure and tensile properties of Ti-35421 alloy
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