Investigation of cracks during electron beam welding of γ-TiAl based alloy

Zhang, Ge; Yin, Qianxing; Zhang, Binggang

doi:10.1016/j.jmatprotec.2020.116727

Cited by 22 publications

(7 citation statements)

References 19 publications

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“…The waveform of the sinusoidal current can be described by a quarter-cycle sinusoidal function. Substituting the initial conditions of t = t 1 , i = 0.95i 1 and t = t 2 = t 1 + T/4, i = i 1 into Equation (10), the sinusoidal current time response can be expressed as…”

Section: An Optimization Methods To Shorten the Current Response Time...mentioning

confidence: 99%

“…A quick response of the solenoid valve is required to accomplish a precise fuel injection volume. 5,6 Electron guns are used in applications of electron-beam evaporation, 7 electron-beam welding, [8][9][10] and electron-beam thermal assessment. [11][12][13] Among them, electron-beam thermal assessment is a novel aerodynamic heating simulation method for testing the thermal protective materials of hypersonic vehicles that has the advantages of high resolution, high energy density, and high energy utilization efficiency in comparison with the hypersonic wind tunnel and quartz lamp heaters.…”

Section: Introductionmentioning

confidence: 99%

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A voltage waveform design method for shortening current response time of a coil

Dou

Long

Yao

et al. 2023

Circuit Theory & Apps

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SummaryCoils are widely used in magnetorheological dampers, solenoid valves, and electron guns, where a quick response of the magnetic induction to the excitation voltage is needed. To achieve a quick response, the response time of the magnetic induction relative to the current and that of the current relative to the voltage should be shortened as much as possible. The latter is dominant in the total response time and can be shortened by using voltage control with an increased resistance or current control. The current time responses of the Helmholtz coils based on voltage control with an increased resistance and current control are measured. The results indicate that the current response times of the coils based on voltage control with resistances of 23.7 and 162 Ω and current control with a resistance of 23.7 Ω are 235.3, 42.3, and 62.1 μs, respectively. The current time responses of the voltage control are smooth, while those of the current control have large oscillations. Based on Kirchhoff's equilibrium equation, an overshoot voltage waveform design method is proposed to shorten the current response time and eliminate the current oscillations. The experimental results show that the current time response is smooth, and the current response time can be shortened by 91.8%, 54.4%, and 68.9% in comparison with those of the former three control cases. The demonstration experiments of the effect of the different control methods on the electron‐beam scanning path and hot spot distribution show that the scanning path and dwell duration are closer to the expected ones with the proposed method. The proposed method is of great value for improving the damping performance of a magnetorheological damper, the accuracy of the fluid injection of a solenoid valve, and the accuracy of the electron‐beam thermal assessment.

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Section: An Optimization Methods To Shorten the Current Response Time...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A voltage waveform design method for shortening current response time of a coil

Dou

Long

Yao

et al. 2023

Circuit Theory & Apps

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show abstract

“…Arc welding is simple and easy to operate, it can be applicable to any joint configuration in ticknesses up to 6-8 mm, but some porosity can be observed since the insufficient of the molten pool [12,13]. High power beam welding mainly include laser welding and electron beam welding, it's high efficiency welding has been widely studied and applied in automation industry, however the high energy input result in keyhole and keyhole induced pores [14,15].…”

Section: Research Statusmentioning

confidence: 99%

Research Progress of Fusion Welding Techniques for Steel to Other Metals

Zeng¹,

Zhang²,

Zhou³

et al. 2022

AJMME

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Welding of dissimilar steel and TiNi shape memory alloys, aluminum alloy, magnesium alloy and other metals is an important issue because of its increasing applications in industries. This review aimed to provide a comprehensive overview of the recent progress in welding and joining of steel and heterogeneous metals and to introduce current research and application. However, the base materials on both sides of the traditional fusion welding must melt and the large melting point difference between the two seriously affects the weld formation. The metal compounds formed by the base materials on both sides also hinder the improvement of the mechanical properties of the joint. The methods available for welding steel and dissimilar metals included fusion welding, brazing, diffusion bonding, friction welding and reactive joining. The current state of the understanding and development of fusion welding method for steel and other metals was addressed. This review focused on the fundamental understanding of the microstructural characteristics, processing and property relationships in the welding and joining of heterogeneous joints.

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“…Laser remelting basically eliminates the coating defects, and greatly improves the elastic modulus and toughness of the coating. The mechanism of selective laser melting, selective electron beam melting and electron beam welding cracks in TiAl alloys has been studied [24,33,34]. However, there are few reports on the crack mechanism of TiAl alloy prepared by LDED, and there is no mature theory and method for crack suppression of TiAl alloy.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the influence of process parameters on crack formation and mechanisms in Ti-48Al-2Cr-2Nb alloy via laser directed energy deposition

Cui,

Liu,

Bian

et al. 2023

Mater. Res. Express

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The Ti-48Al-2Cr-2Nb alloy was fabricated using laser directed energy deposition(LDED), and the impact of various process parameters on the macroscopic crack morphology was analyzed. The mechanism of crack formation was investigated through the analysis of crack microstructure, phase composition, crystal orientation, and elemental composition. The process parameters were optimized by response surface methodology(RSM) and the laser remelting method was used to suppress the crack formation. The results showed that the cracks were mainly caused by lack of fusion, residual stress during LDED and stress between different phases of TiAl alloy. The mismatch of process parameters results in insufficient energy for powder melting, ultimately leading to lack of fusion occurrence. To minimize crack formation, the response surface method was employed to optimize process parameters and reduce crack generation. The higher temperature gradient led to the existence of residual stress in the sample, and the higher stress between α 2 phase and B2 phase formed in the deposition process due to the difference of thermal expansion coefficients. The region where the two phases converge was the region with the highest crack sensitivity, and cracks occured in the region where α 2 phase and B2 phase converge in the form of excellent transgranular fracture. The samples prepared by using the optimized parameters can effectively restrain the cracks caused by lack of fusion, but can not restrain the cracks caused by the stress between phases. Laser remelting after LDED can not only reduce the temperature gradient and residual stress, but also remelt the unmelted powder on the surface of the as-deposited samples, effectively inhibiting the generation of cracks, and preparing crack-free samples.

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Investigation of cracks during electron beam welding of γ-TiAl based alloy

Cited by 22 publications

References 19 publications

A voltage waveform design method for shortening current response time of a coil

A voltage waveform design method for shortening current response time of a coil

Research Progress of Fusion Welding Techniques for Steel to Other Metals

Investigation of the influence of process parameters on crack formation and mechanisms in Ti-48Al-2Cr-2Nb alloy via laser directed energy deposition

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