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Guozhen, China

Wang X.-X.,Baoti Group Co. | Hui S.-X.,General Research Institute for Nonferrous Metals, China
Materials Science Forum

Effect of heat treatment on the damage tolerance properties of a newly developed middle strength high damage tolerance Ti-6Al-2Zr-2V-1.5Mo ELI alloy plate has been investigated in this paper by testing fracture toughness and fatigue crack-extending rate of the plate under three heat treatment conditions and fractograph inspection of the samples. It has been found that with the increasing of the primary annealing temperature from 900°C to 950°C, the fracture toughness increased and the fatigue crack extending rate decreased significantly. Microstructural observation has found that the crack expanded through the α beaming and mainly are perpendicular to the α orientation in the lamellar structure which annealed in α+β phase zone. For the Widmanstaten structure, which can be obtained from annealing in single β phase zone, the continuous grain boundary α phase and α beaming boundary hinder the crack expanding significantly. © (2011) Trans Tech Publications. Source

Zhang W.J.,General Research Institute for Nonferrous Metals, China | Song X.Y.,General Research Institute for Nonferrous Metals, China | Hui S.X.,General Research Institute for Nonferrous Metals, China | Ye W.J.,General Research Institute for Nonferrous Metals, China | And 2 more authors.
Materials Science and Engineering A

The effect of lamellar α phase (αL) thickness on tensile behavior at 700°C of BTi-6431S titanium alloy is investigated. Two types of bi-modal microstructures are introduced through different heat treatments. Both of them have similar volume fraction of equiaxed α phases (αe). One has thick α lamella named BTL, and another has fine α lamella named BFL. The results show that dynamic recrystallization (DRX) happens in the α phase during tensile process at 700°C. After being deformed at 700°C, the shape of αL in BFL and BTL transforms into sphere. BFL possesses higher tensile strength, and the elongation is twice as large as BTL at 700°C. Compared to the thick αL, the fine αL has more excellent accommodative deformation capability. There are cracks found to be of wedge type located at the grain triple junctions in both BFL and BTL. In addition, some small voids stay at the lamellar boundaries in BTL. In order to acquire a good combination of tensile strength and elongation at 700°C for BTi-6431S alloy, the thickness of αL should be reduced. © 2013 Elsevier B.V. Source

Hao W.,Baoti Group Co.
Ti 2011 - Proceedings of the 12th World Conference on Titanium

Titanium's high strength, low density, excellent flexibility and strong spring-back characteristics, high-temperature performance, good corrosion resistance, and biocompatibility are highly beneficial in developing emerging applications. Titanium emerging applications are developing rapidly in recently years besides traditional aeronautical and aerospace, military, chemical processing applications. The world titanium emerging application market, including automobile, ocean engineering, medical implant, architecture, computer, sports articles, consume goods and geothermal industry are overviewed in the paper, focusing on the automotive industry, marine engineering and medical implant application status. Prospects of emerging market in the future are also discussed in the paper. Source

Li C.-L.,General Research Institute for Nonferrous Metals, China | Mi X.-J.,General Research Institute for Nonferrous Metals, China | Ye W.-J.,General Research Institute for Nonferrous Metals, China | Hui S.-X.,General Research Institute for Nonferrous Metals, China | And 2 more authors.
Journal of Alloys and Compounds

A study on the microstructural characteristics and tensile properties of a new high strength Ti-6Cr-5Mo-5V-4Al alloy were investigated. Both the α/β and β solution treatment and subsequent aging at temperatures ranging from 460 °C to 560 °C were introduced to investigate the microstructural characteristics and microstructure-property relationships. The results show that the primary α phase formed during the α/β solution treatment can increase the stability of the β matrix and then restrain the size of secondary α phase during subsequent aging. In the α/β solution plus aging condition, the secondary α phase with the size of about 1 μm results in a high strength above 1500 MPa with -6% of elongation. The β solution treatment leads to the least stable β matrix and the greatest driving force for secondary α phase, so coarser α phases tend to form during aging. The β solution plus aging does not lead to attractive high strength because of the coarser and non-uniform α phase. And it also leads to a poorer combination of strength and ductility than the α/β solution plus aging. Direct aging exhibits the best strengthening. The ultimate strength of the alloy is about 1600 MPa with acceptable elongations of 6.5-7.5% when direct aged at 500 °C for 2-8 h. It benefits from the mixed microstructure with nano-scale and micron-scale α phases. However, more detailed investigations are needed to improve the ductility. As a whole, the alloy can be heat treatable to obtain an excellent balance of strength and ductility, and provide abundant stress levels with optional ductility (900-1600 MPa in ultimate strength and 6-20% in elongation). © 2012 Elsevier B.V. All rights reserved. Source

Jiang H.-T.,University of Science and Technology Beijing | Yan X.-Q.,University of Science and Technology Beijing | Liu J.-X.,Baoti Group Co. | Duan X.-G.,University of Science and Technology Beijing
Transactions of Nonferrous Metals Society of China (English Edition)

The effect of heat treatment on microstructure and mechanical properties of the Ti-steel explosive-rolling clad plate was elaborated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), micro-hardness test and shear test. The composites were subjected to heat treatment at temperature of 650-950 °C for 60 min. The results show that the heat treatment process results in a great enhancement of diffusion and microstructural transformation. The shear strength decreases as the treatment temperature increases. Heated at 850 °C or below, their shear strength decreases slowly as a result of the formation of TiC in the diffusion interaction layer; while at the temperature of 850 °C or above, the shear strength decreases obviously, which is the consequence of a large amount of Ti-Fe intermetallics (Fe2Ti/FeTi) along with some TiC distributing continuously at diffusion reaction layer. © 2014 The Nonferrous Metals Society of China. Source

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