scholarly journals FAST-forge of Diffusion Bonded Dissimilar Titanium Alloys: A Novel Hybrid Processing Approach for Next Generation Near-Net Shape Components

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 654 ◽  
Author(s):  
Jacob Pope ◽  
Martin Jackson
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Axial Compression ◽  
Microstructural Analysis ◽  
Bond Line ◽  
Small Scale ◽  
Compression Tests ◽  
Die Forging ◽  
Closed Die Forging ◽  
Near Net Shape

Material reductions, weight savings, design optimisation, and a reduction in the environmental impact can be achieved by improving the performance of near-net shape (NNS) titanium alloy components. The method demonstrated in this paper is to use a solid-state approach, which includes diffusion bonding discrete layers of dissimilar titanium alloy powders (CP-Ti, Ti-6Al-4V and Ti-5Al-5Mo-5V-3Cr) using field-assisted sintering technology (FAST), followed by subsequent forging steps. This article demonstrates the hybrid process route, firstly through small-scale uni-axial compression tests and secondly through closed-die forging of dissimilar titanium alloy FAST preforms into an NNS (near-net shape) component. In order to characterise and simulate the underlying forging behaviour of dissimilar alloy combinations, uni-axial compression tests of FAST cylindrical samples provided flow stress behaviour and the effect of differing alloy volume fractions on the resistance to deformation and hot working behaviour. Despite the mismatch in the magnitude of flow stress between alloys, excellent structural bond integrity is maintained throughout. This is also reflected in the comparatively uncontrolled closed-die forging of the NNS demonstrator components. Microstructural analysis across the dissimilar diffusion bond line was undertaken in the components and finite element modelling software reliably predicts the strain distribution and bond line flow behaviour during the multi-step forging process.

scholarly journals Application of the Strain Compensation Model and Processing Maps for Description of Hot Deformation Behavior of Metastable β Titanium Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2021
Author(s):  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Aneta Łukaszek-Sołek ◽  
Krystian Zyguła ◽  
Marek Wojtaszek
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Flow Behavior ◽  
Microstructural Analysis ◽  
Calculated Data ◽  
Processing Temperature ◽  
Processing Maps ◽  
Compression Tests ◽  
Strain And Strain Rate ◽  
Average Absolute Relative Error

The flow behavior of metastable β titanium alloy was investigated basing on isothermal hot compression tests performed on Gleeble 3800 thermomechanical simulator at near and above β transus temperatures. The flow stress curves were obtained for deformation temperature range of 800–1100 °C and strain rate range of 0.01–100 s−1. The strain compensated constitutive model was developed using the Arrhenius-type equation. The high correlation coefficient (R) as well as low average absolute relative error (AARE) between the experimental and the calculated data confirmed a high accuracy of the developed model. The dynamic material modeling in combination with the Prasad stability criterion made it possible to generate processing maps for the investigated processing temperature, strain and strain rate ranges. The high material flow stability under investigated deformation conditions was revealed. The microstructural analysis provided additional information regarding the flow behavior and predominant deformation mechanism. It was found that dynamic recovery (DRV) was the main mechanism operating during the deformation of the investigated β titanium alloy.

Hot working of SP-700 titanium alloy with lamellar α + β starting structure using a processing map

2020 ◽  
Vol 111 (4) ◽  
pp. 297-306
Author(s):  
Amir Hosein Sheikhali ◽  
Maryam Morakkabati
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Hot Deformation ◽  
Processing Map ◽  
Microstructural Analysis ◽  
Shear Bands ◽  
Alpha Phase ◽  
Strain Rates ◽  
Compression Tests ◽  
Temperature Range

Abstract In this study, hot deformation behavior of SP-700 titanium alloy was investigated by hot compression tests in the temperature range of 700-9508C and at strain rates of 0.001, 0.1, and 1 s-1. Final mechanical properties of the alloy (hot compressed at different strain rates and temperatures) were investigated using a shear punch testing method at room temperature. The flow curves of the alloy indicated that the yield point phenomenon occurs in the temperature range of 800- 9508C and strain rates of 0.1 and 1 s-1. The microstructural analysis showed that dynamic globularization of the lamellar α phase starts at 7008C and completes at 8008C. The alpha phase was completely eliminated from b matrix due to deformation- induced transformation at 8508C. The microstructure of specimens compressed at 8508C and strain rates of 0.001 and 0.1 s-1showed the serration of beta grain boundaries, whereas partial dynamic recrystallization caused a necklace structure by increasing strain rate up to 1 s-1. The specimen deformed at 7008C and strain rate of 1 s-1was located in the instability region and localized shear bands formed due to the low thermal conductivity of the alloy. The processing map of the alloy exhibited a peak efficiency domain of 54% in the temperature range of 780-8108C and strain rates of 0.001- 0.008 s-1. The hot deformation activation energy of the alloy in the α/β region (305.5 kJ mol-1) was higher than that in the single-phase β region (165.2 kJ mol-1) due to the dynamic globularization of the lamellar a phase.

scholarly journals Hot deformation behavior of TC18 titanium alloy

2013 ◽  
Vol 17 (5) ◽  
pp. 1523-1528
Author(s):  
Bao-Hua Jia ◽  
Wei-Dong Song ◽  
Hui-Ping Tang ◽  
Jian-Guo Ning
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Testing Machine ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Hot Deformation Behavior

Isothermal compression tests of TC18 titanium alloy at the deformation temperatures ranging from 25?C to 800?C and strain rate ranging from 10-4 to 10-2 s-1 were conducted by using a WDW-300 electronic universal testing machine. The hot deformation behavior of TC18 was characterized based on an analysis of the true stress-true strain curves of TC18 titanium alloy. The curves show that the flow stress increases with increasing the strain rate and decreases with increasing the temperature, and the strain rate play an important role in the flow stress when increasing the temperatures. By taking the effect of strain into account, an improved constitutive relationship was proposed based on the Arrhenius equation. By comparison with the experimental results, the model prediction agreed well with the experimental data, which demonstrated the established constitutive relationship was reliable and can be used to predict the hot deformation behavior of TC18 titanium alloy.

Experimental studies of upsetting of VT6 titanium blanks by die-forging hammer filler ram

2020 ◽  
pp. 408-411
Author(s):  
V.Yu. Lavrinenko ◽  
A.I. Alimov ◽  
T.Kh. Ayupov ◽  
A.I. Izikaeva
Keyword(s):  
Titanium Alloy ◽  
Microstructural Analysis ◽  
Experimental Studies ◽  
Deformation Degree ◽  
Die Forging

The results of experimental studies of upsetting of the blanks from VT6 titanium alloy by using fi ller ram of die-forging hammer M2140 in Moscow plant "Avangard" are presented. The increasing of the deformation degree of blanks by 1.12 times in comparison with standard hammer ram is obtained. The microstructural analysis of the obtained blanks allows to established the absence of changes in the microstructure of the blank after upsetting by hammer fi ller ram in comparison with standard upsetting.

Modeling of Flow Stress for one New Kind of Metastable β Titanium Alloy at High Temperature

2011 ◽  
Vol 311-313 ◽  
pp. 716-721
Author(s):  
Zhe Jun Wang ◽  
Hong Fu Qiang ◽  
Xue Ren Wang
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Flow Stress ◽  
Constitutive Model ◽  
Flow Behavior ◽  
Accurate Estimate ◽  
Compression Tests ◽  
Stress Strain ◽  
Nonlinear Constitutive Equation ◽  
Peak Value

Based on the characteristics of the flow stress curves for one new kind of metastable Ti2448 titanium alloy from isothermal hot compression tests, the constitutive model was developed to describe the relation between flow stress and strain, strain rate, deformation temperature completely. During this process, the flow behavior of alloy at high temperature undergo flow softening caused by dynamic recovery (DRV) was modeled by the adopted hyperbolic sine function based on the unified viscoplasticity theory, the further drop in flow stress after the peak value in stress-strain curves was assumed to be caused by temperature rise and the constitutive model was modified accordingly. Additionally, the material constants were determined by optimization strategies, which is a new method to solve the nonlinear constitutive equation. The stress-strain curves predicted by the developed constitutive model well agree with experimental results, which confirms that the developed constitutive model gives an accurate estimate of the flow stress of Ti2448 titanium alloy and can provide an effect method to model the flow behavior of metastable titanium alloy at high temperature.

HOT COMPRESSION BEHAVIOR OF ONE KIND OF META-STABLE β TITANIUM ALLOY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 777-782 ◽  
Author(s):  
LIYING ZENG ◽  
PENG GE ◽  
XIAONAN MAO ◽  
YONGQING ZHAO ◽  
LIAN ZHOU
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Deformation Temperature ◽  
Strain Rates ◽  
Compression Tests ◽  
Compression Behavior ◽  
Grain Sizes ◽  
Test Conditions ◽  
Plastic Deformation Process ◽  
Metal Research

One kind of meta-stable β titanium alloy with grain sizes less than 1µm was developed using conventional plastic deformation process in Northwest Institute for Nonferrous Metal Research (NIN). The so called Ti - B 19 alloy ( Ti - Al - Mo - V - Cr - Zr ) possesses excellent strength and toughness. In order to excavate the potential workability of the alloy, isothermal compression tests were carried out on the Gleeble-1500 thermal simulator at the temperature from 750°C to 1000°C and strain rate from 0.001 s-1 to 10s-1. The results indicate that the flow stresses of the alloy will be heavily influenced by the strain rates and deformation temperature. The flow stress decrease with the increase of deformation temperature, and increase with the increment of strain rates. A constitutive equation for the flow stress has been defined and the test conditions for a homogeneous deformation evaluated, and the material constants including activation energy Q , stress exponent n and constant ln ( A ) were also obtained.

scholarly journals Flow Stress Prediction and Hot Deformation Mechanisms in Ti-44Al-5Nb-(Mo, V, B) Alloy

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2044 ◽  
Author(s):  
Tianrui Li ◽  
Guohuai Liu ◽  
Mang Xu ◽  
Bingxing Wang ◽  
Tianlian Fu ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Microstructural Analysis ◽  
Constitutive Relationship ◽  
Deformation Mechanisms ◽  
Compression Tests ◽  
Ann Model ◽  
Stress Prediction

To elucidate the hot deformation characteristics of TiAl alloys, flow stress prediction, microstructural evolution and deformation mechanisms were investigated in Ti-44Al-5Nb-1Mo-2V-0.2B alloy by isothermal compression tests. A constitutive relationship using the Arrhenius model involving strain compensation and back propagation artificial neural network (BP-ANN) model were developed. A comparison of two models suggested that the BP-ANN model had excellent capabilities and was more accurate in predicting flow stress. Based on the microstructural analysis, bending and elongation of colonies, γ and B2 grains were the main microstructural constituents at low temperature and high strain rate. Dynamic recrystallization (DRX) of γ and dynamic recovery (DRY) of β/B2 were the main deformation mechanisms. With the increase of temperature and decrease of strain rate, phase transformation played an important role. The flake-like γ precipitates in B2 grains, and a coarsening of γ lamellae via α lath dissolution during compression were observed. Additionally, the flow softening process commenced with dislocation pile-up and formation of sub-grain boundaries, followed by grain refinement, twins and nano-lamellar nucleation. Continuous DRX and phase transformation promoted the formability of Ti-44Al-5Nb-1Mo-2V-0.2B alloy.

High Temperature Deformation Behavior of Ti-7333 Titanium Alloy and its Flow Stress Model

2012 ◽  
Vol 538-541 ◽  
pp. 945-950 ◽  
Author(s):  
Jiang Kun Fan ◽  
Hong Chao Kou ◽  
Min Jie Lai ◽  
Bin Tang ◽  
Hui Chang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Model ◽  
Compression Tests ◽  
Flow Stress Model

The effects of processing parameters on deformation behavior of a new near β titanium alloy were investigated by using compression tests. The experiments were carried out in the Gleeble-3800 thermal and mechanical simulator in the temperature range of 770-970°C and strain rate range of 10-3-10s-1, and height direction reduction of 70%. The results show that the flow stress of Ti-7333 titanium alloy increases obviously with the strain and reaches a peak, then decreases to a steady value. The steady and peak stress significantly decreases with the increase of deformation temperature and decrease of strain rate. The flow stress model of Ti-7333 titanium alloy during high temperature deformation was established by using the regression method. The average relative difference between the calculated and experimental flow stress is 6.33%. The flow stress model can efficiently predict the deformation behavior of Ti-7333 titanium alloy during high temperature deformation.

scholarly journals Flow Stress of beryllium: Attempt for a Bayesian Crossed-data Analysis from Hopkinson Bars to Rayleigh-Taylor Instabilities

2018 ◽  
Vol 183 ◽  
pp. 01004 ◽  
Author(s):  
Gabriel Seisson ◽  
Vincent Dubois ◽  
Cyril Bolis ◽  
Christophe Denoual
Keyword(s):  
Flow Stress ◽  
Axial Compression ◽  
Strength Model ◽  
Flow Modeling ◽  
Compression Tests ◽  
High Explosives ◽  
Dynamic Experiments ◽  
Split Hopkinson ◽  
Compression Data ◽  
Split Hopkinson Pressure Bars

In this paper, we demonstrate by a Bayesian approach the incapacity of the Preston-Tonks-Wallace (PTW) strength model to represent, with the same set of parameters, the flow stress of beryllium in both moder-ate and highly dynamic experiments, and suggest hypotheses explaining that limitation. Usual plasticity models such as Johnson-Cook (JC) and PTW are mostly adjusted onto quasi-static and dynamic uni-axial compression data acquired thanks to compression machines and split Hopkinson pressure bars. Nonetheless, they may be used beyond the range of mechanical loading in which they have been fitted. This is the case of the simulations of solid Rayleigh-Taylor instabilities (RTI) driven by high explosives. A recent work of Henry de Frahan et al. noticed the inability of various plasticity models to stand for the growth of beryllium RTI. Amongst them, the PTW model has been particularly examined through four different sets of parameters, each of them largely un-derestimates the growth of the experimental instability. Thus, this work is an attempt, regarding the plastic flow modeling of beryllium, to conciliate uni-axial compression tests (CT) and RTI by means of a crossed Bayesian analysis.

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