Mechanism of saturated flow stress during hot tensile deformation of a TA15 Ti alloy

Liu, Gang; Wang, Kehuan; He, Binbin; Huang, Mingxin; Yuan, Shijian

doi:10.1016/j.matdes.2015.07.100

Cited by 41 publications

(9 citation statements)

References 31 publications

(38 reference statements)

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“…The effects of the microstructure on hot tensile deformation behavior of 7075 alloy was evaluated by Wang and his co-workers [9]. Further, a similar dependence of the fracture behavior on the deformation conditions was reported for the IMI834 titanium alloy [10], TA15 Ti alloy [11], Mg-9.3Li-1.79Al-1.61Zn alloy [12], and other alloys [13,14], all of which indicate that hot tensile tests are a powerful tool to investigate the fracture and high-temperature behavior of alloys. However, there is little information about the fracture behavior for 35CrMo steel, and most studies to date have focused on the surface treatment and related performance [15][16][17][18][19].…”

Section: Methodsmentioning

confidence: 54%

Hot Tensile and Fracture Behavior of 35CrMo Steel at Elevated Temperature and Strain Rate

Xiao

Huang

Liu

et al. 2016

Metals

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Abstract:To better understand the tensile deformation and fracture behavior of 35CrMo steel during hot processing, uniaxial tensile tests at elevated temperatures and strain rates were performed. Effects of deformation condition on the flow behavior, strain rate sensitivity, microstructure transformation, and fracture characteristic were characterized and discussed. The results indicated that the flow stress was sensitive to the deformation condition, and fracture occurs immediately after the peak stress level is reached, especially when the temperature is low or the strain rate is high. The strain rate sensitivity increases with the deformation temperature, which indicates that formability could improve at high temperatures. Photographs showing both the fracture surfaces and the matrix near the fracture section indicated the ductile nature of the material. However, the fracture mechanisms varied according to the deformation condition, which influences the dynamic recrystallization (DRX) condition, and the DRX was accompanied by the formation of voids. For samples deformed at high temperatures or low strain rates, coalescence of numerous voids formed in the recrystallized grains is responsible for fracture, while at high strain rates or low temperatures, the grains rupture mainly by splitting because of cracks formed around the inclusions.

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Section: Methodsmentioning

confidence: 54%

Hot Tensile and Fracture Behavior of 35CrMo Steel at Elevated Temperature and Strain Rate

Xiao

Huang

Liu

et al. 2016

Metals

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“…The contribution of dislocation strengthening can be expressed by the Taylor hardening model. [ 15,29 ]

Δ σ_{normald} = M α G b \sqrt{ρ}

where M is the Taylor factor (taken as 5 for random Mg polycrystals [ 10 ] ), α is 0.20 for basal−basal dislocation interaction, [ 30 ] G is the shear modulus of the Mg matrix (16.7 GPa for Mg), b the magnitude of Burger's vector of the slip dislocations (0.3196 nm for (0001) basal plane of Mg [ 10 ] ), and ρ is the total dislocation density which includes GND and statistically stored dislocations (SSD). [ 24,31 ] Although the SSD density is not obtained from electron backscattered diffraction (EBSD) data, it is reported that the GND density dominated the total dislocation density at small and medium strains of the polycrystalline metals.…”

Section: Discussionmentioning

confidence: 99%

“…[ 24,31 ] Although the SSD density is not obtained from electron backscattered diffraction (EBSD) data, it is reported that the GND density dominated the total dislocation density at small and medium strains of the polycrystalline metals. [ 29,31 ] Generally, compared with plastic deforming process (extrusion, rolling, and forging, etc. ), the strains of the sintered samples are small during SPS sintering process.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Sintering Temperature on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy via Spark Plasma Sintering

et al. 2021

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AZ91 alloy is the commonly used magnesium alloy due to its castability and high specific strength. [1,2] However, the cast AZ91 alloy shows low absolute strength and poor ductility due to large grain size, coarse precipitates, and close-packed hexagonal (HCP) structure, which greatly hinder its application. [2][3][4] Grain refinement is one effective way to improve the mechanical properties of Mg alloys. Plastic deformation technology is an important approach for grain refinement of magnesium alloys. It is well accepted that the strong basal texture forms in plastic deformation processing. However, when compressed along the rolling direction or extrusion direction, the {1012} tension twinning is activated, resulting in a relatively low compressive yield strength (CYS). [5] Thus, tension twin suppression is an important issue for improving compressive properties of Mg alloys. Grain refinement and texture weakening are two effective strategies for tension twin suppression. As an innovative processing technology, spark plasma sintering (SPS) combines high uniaxial pressure with pulsing direct electric current to heat the powder, which achieves the densification of sintered samples in a short time and forms a finer microstructure without texture. [6][7][8] Furthermore, SPS technology has been used to fabricate fine-grain Mg alloys with high compressive strength compared with the cast Mg alloys. [9][10][11] Recent researches showed that the mechanical properties of magnesium alloy are determined by the grain size, amount of precipitates, and solute content, which are greatly related to the sintering temperature. [10][11][12] The grain refinement, precipitation, and solid solution strengthening mechanisms have been developed to explain the impact of microstructure on the mechanical properties of the SPS-sintered magnesium alloys. [10] In addition, the dislocation strengthening mechanism plays an important role in metals with high density of dislocations. [13][14][15] It should be noticed that the gas-atomized powder contains a high degree of dislocations. [16] However, there is little report on the evolution of dislocations density at different sintering temperatures for SPS Mg alloys. Consequently, the effect of dislocation strengthening on the mechanical properties of the SPS-sintered magnesium alloys is yet not clear.In this work, gas-atomized powder was used to prepare AZ91 alloys by SPS. This study aims to quantitatively investigate the effect of the SPS sintering temperature on the microstructure (the amount and distribution of precipitates, the dislocation density, and the grain size) and the mechanical properties of the

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“…TA15 titanium alloy, which is provided with excellent thermal stability and welding performance, applies widely in the welding parts of aerospace engines and military industries [6][7]. Therefore, it is the connection of titanium alloy that is necessarily involved in manufacturing.…”

Section: Introductionmentioning

confidence: 99%

Effect of Laser Welding Speed on Grain Morphology and Tensile Property of TA15 Titanium Alloy Bottom-Locking Joint

Wang¹,

Qi²,

Zhao³

et al. 2021

Preprint

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The laser welding of TA15 titanium alloy with the bottom-locking joints is carried out by TruDisk-12003 disc laser. In this paper, the microstructure and tensile properties of welded joints with different welding speeds are studied. The microstructure is observed by optical microscope. The tensile fracture morphology and chemical composition are analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) respectively. The experimental results show that the width of weld zone (WZ) is decreased significantly with the increasing of welding speed. The β columnar crystal shows respective morphology and growth direction in WZ under different welding speeds, meanwhile, the number of acicular martensite which is precipitated in columnar crystal also presents different. Besides, the aggregate growth zone of columnar crystal at the bottom of weld zone gets smaller with the increase of welding speed. The maximum tensile strength for the TA15 titanium alloy bottom-locking joint, which is fractured at weld joint, reaches 89% of the BM. Besides, the EDS results illustrate that the burning loss of stabilization element is inevitable.

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Mechanism of saturated flow stress during hot tensile deformation of a TA15 Ti alloy

Cited by 41 publications

References 31 publications

Hot Tensile and Fracture Behavior of 35CrMo Steel at Elevated Temperature and Strain Rate

Hot Tensile and Fracture Behavior of 35CrMo Steel at Elevated Temperature and Strain Rate

Effect of Sintering Temperature on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy via Spark Plasma Sintering

Effect of Laser Welding Speed on Grain Morphology and Tensile Property of TA15 Titanium Alloy Bottom-Locking Joint

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