Mechanical properties and microstructural characteristics of laser and electron-beam welds in V–4Cr–4Ti

Chung, H.M.; Park, J.-H; Strain, R.V.; Leong, Keng H.; Smith, D.L.

doi:10.1016/s0022-3115(98)00327-4

Cited by 11 publications

(4 citation statements)

References 5 publications

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“…Chung et al carried out PWHT at 1273 K and one hour on laser and EB welds of V-4Cr-4Ti, and found significant downward shift of DBTT [5]. They have examined microstructure after PWHT and concluded that dislocation recovery and precipitate aggregation contributed to cleaning the matrix.…”

Section: Comparison With Past Researchmentioning

confidence: 99%

“…Recent efforts have made a significant progress in fabrication, joining and coating technology of the alloys [1,2]. Especially the welding technology has advanced largely including gas-tungsten-arc (GTA) welding [3,4], laser welding [5] and electron beam (EB) welding [6].…”

Section: Introductionmentioning

confidence: 99%

“…Some previous efforts showed heat treatment of weld joints recovered DBTT [3,5], but systematic investigation has not been carried out.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Precipitation and Mechanical Property Change by Heat Treatments for the Laser Weldments of V-4Cr-4Ti Alloy

Muroga

Heo

Nagasaka

et al. 2015

Plasma and Fusion Research

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Bead-on-plate welds were produced on the 4 mm-thick V-4Cr-4Ti alloy (NIFS-HEAT-2), using a 2.0 kW YAG laser. The post-weld heat treatments (PWHT) were carried out in various conditions. Microstructures, Vickers hardness and Charpy impact properties were obtained for the weld metal after the PWHT. After PWHT for one hour, the hardness increased and after the peak declined with temperature. At 873 K, the hardness increased and after the peak declined with the time of PWHT. Microstructural observation showed that high density of fine precipitates formed homogeneously when the hardness increased, but the precipitate distribution changed into heterogeneous forming islands of developed precipitate aggregates, coincident with decrease in hardness and recovery of impact properties. Optical microscope observations suggested that a cellular structure of precipitate aggregate region was formed by PWHT. Microchemical analysis showed that Ti was enriched in the precipitate aggregate region. Therefore the areal oscillation of Ti concentration with cellular structures formed by melting and resolidification during the welding resulted in the heterogeneous precipitation by the following PWHT. The precipitation in the Ti-rich area purified the matrix of the weld metal and induced the recovery of hardening and impact property degradation. Optimum PWHT conditions were discussed according to the present results.

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Section: Comparison With Past Researchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Precipitation and Mechanical Property Change by Heat Treatments for the Laser Weldments of V-4Cr-4Ti Alloy

Muroga

Heo

Nagasaka

et al. 2015

Plasma and Fusion Research

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“…

ABSTRACT V-Cr-Ti alloys are among the leading candidate materials for the frost wall and other structural materials applications in fusion power reactors because of several important advantages including inherently low irradiation-induced activity, good mechanical properties, good compatibility with lithium, high thermal conductivity and good resistance to irradiation-induced swelling and damage [1]. However, weldability of these alloys in general must be demonstrated, and laser welding, specifically, must be developed.

…”

mentioning

confidence: 99%

The effect of laser welding process parameters on the mechanical and microstructural properties of V-4Cr-4Ti structural materials.

Reed¹,

Natesan²,

Xu³

et al. 2000

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V-Cr-Ti alloys are among the leading candidate materials for the frost wall and other structural materials applications in fusion power reactors because of several important advantages including inherently low irradiation-induced activity, good mechanical properties, good compatibility with lithium, high thermal conductivity and good resistance to irradiation-induced swelling and damage [1]. However, weldability of these alloys in general must be demonstrated, and laser welding, specifically, must be developed. Laser welding is considered to be an attractive process for construction of a reactor due to its high penetrating power and potential flexibility. This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. The effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld.

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Recent progress of vanadium-based alloys for fusion application

et al. 2021

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Mechanical properties and microstructural characteristics of laser and electron-beam welds in V–4Cr–4Ti

Cited by 11 publications

References 5 publications

Heterogeneous Precipitation and Mechanical Property Change by Heat Treatments for the Laser Weldments of V-4Cr-4Ti Alloy

Heterogeneous Precipitation and Mechanical Property Change by Heat Treatments for the Laser Weldments of V-4Cr-4Ti Alloy

The effect of laser welding process parameters on the mechanical and microstructural properties of V-4Cr-4Ti structural materials.

Recent progress of vanadium-based alloys for fusion application

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