Phase transformation effect in distortion and residual stress of thin-sheet laser welded Ti-alloy

Kumar, Bikash; Bag, Swarup

doi:10.1016/j.optlaseng.2019.06.008

Cited by 52 publications

(7 citation statements)

References 53 publications

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“…This shrinkage under external constraint cause distortion and residual stresses. As previously reported by the researchers, this distortion is induced due to temperature change [11]. In order to counter this distortion, a change of temperature field can be a good option to follow.…”

Section: Introductionmentioning

confidence: 83%

Influence of liquid nitrogen on residual circumferential distortion, weld penetration and delta-ferrite distribution in clamped tungsten inert gas welded butt joint of 316 stainless steel

et al. 2020

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AISI 316 stainless steel (SS316) is an attractive material for industrial applications. Welding of this alloy can lead to severe distortion that often results in dimensional inaccuracies. With the help of specially designed fixture and clamping mandrels, tungsten inert gas (TIG) welding on SS316 pipes is employed to investigate the effect of liquid nitrogen on the circumferential distortion, weld penetration and delta-ferrite distribution in different welding zones. The experimental results reveal that the presence of trailing heat sink in TIG welded butt joint has almost zero distortion at a distance of 30 mm from the weld centerline and 64% decrement in residual circumferential distortion at the center of the weld bead. A metallurgical microscope is used to find the weld penetration, (fusion zone) FZ and (heat affected zone) HAZ. The results illustrate that increase in current and the presence of intensive cooling media yield deeper penetration in TIG welding. Liquid nitrogen (LN 2 ) also constricts the FZ and HAZ. Instead of evaluating delta-ferrite contents using the ferrite number technique, a MATLAB ® code for image processing is developed to evaluate the delta-ferrite distribution in the different regions of a single-pass weldment. Delta-ferrite contents are maximum in the presence of intensive cooling media near HAZ and increase with an increase in the current value. Hence, TIG welding with LN 2 as trailing heat sink is the most suitable scheme to weld industrial pipes owing to its higher weld penetration, higher delta-ferrite contents and minimum circumferential distortion.

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Section: Introductionmentioning

confidence: 83%

Influence of liquid nitrogen on residual circumferential distortion, weld penetration and delta-ferrite distribution in clamped tungsten inert gas welded butt joint of 316 stainless steel

et al. 2020

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“…When the cooling rate is greater than 410 • C/s, martensitic transformation occurs dominantly, and the formation of martensite is a non-diffusion or displacement solid-state phase transition that rapidly changes the crystal structure without rearranging the atoms. Similarly, it was assumed that the fraction of α 、 phase increased by the equivalent amount of dissolution of the β phase, and it was assumed that the martensitic transformation follows the Koistenen-Marburger formulation [28,29], which is expressed as Equation (7).…”

Section: Solid-state Metallurgical Phase Transformationsmentioning

confidence: 99%

Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

Liu

Zheng

et al. 2023

Metals

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To overcome the detrimental effect of residual stress in welded joints, which affects the overall performance of the welded structure, this paper studies the magnitude and distribution of residual stress after welding and local post-weld heat treatment (PWHT). The coupled thermo-metallurgical-mechanical model for welding 6 mm thick Ti-6Al-4V (TC4) titanium alloy plates was established, the evolution of the SSPT and its effect on the residual stress were quantitatively analyzed, and a parametric analysis of local PWHT was performed. The results demonstrated that there was good agreement between the numerical results and the experimental data. Due to the cooling rate reaching 327 °C/s, the volume fraction of α、 in the fusion zone (FZ) reached 0.218 after welding and decreased by 90.83% after PWHT when the heating temperature was 700 °C. The peak value of the longitudinal residual stress can reach 686.4 MPa after welding with SSPT, which was 11.38% lower than that without SSPT, and it decreased by 65.6% after PWHT when the heating temperature was 900 °C. The research results demonstrate that SSPT has a significant effect on residual stress, and PWHT can obviously reduce the residual stress, which provides a certain reference for welding TC4 titanium alloy plates.

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“…WRS relaxation may occur when dislocation movements engender induced by additional applied loads or thermal energy, which change the local plastic constraints and results in residual stress redistribution [15] [24]. In general, in the heat affected zone, measurable relaxation under tension evidently occurred after the first cycle, and continued this behavior at a relatively low rate under the increased cycle numbers of loading.…”

Section: Wrs Relaxationmentioning

confidence: 99%

Experimental Investigation on Residual Stress Distribution and Relaxation Effect at Double-Side Welded Rib-to-Deck Joints of Orthotropic Steel Decks

2022

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The welding residual stresses (WRS) will shorten the fatigue resistance of rib-to-deck (RTD) joints of orthotropic steel decks (OSDs) in bridge engineering. It is essential to obtain WRS and its distribution to accurately assess the fatigue damage of RTD joints in OSDs subjected to vehicle loads. Initial WRS will release under cyclic loading, resulting in the redistribution of WRS in steel bridges. To estimate the relaxation of initial transverse WRS, experimental investigations on WRS distribution in initial state and its relaxation law under cyclic loading were conducted of the double-side welded RTD joints using ultrasonic Non-destructive Testing. The results indicate that the initial transverse WRS at the heat affected zone of both inside and outside of decks vary from 0.50fy to 0.83fy, and transform within the range of 0.27fy~0.43fy at both inside and outside surfaces of U-ribs. WRS relaxation is prone to be activated under cyclic loading, especially at the first cycles. Afterwards, the WRS proceed with relaxation at a lower rate, remaining almost stable with more repetitions of loading.

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Phase transformation effect in distortion and residual stress of thin-sheet laser welded Ti-alloy

Cited by 52 publications

References 53 publications

Influence of liquid nitrogen on residual circumferential distortion, weld penetration and delta-ferrite distribution in clamped tungsten inert gas welded butt joint of 316 stainless steel

Influence of liquid nitrogen on residual circumferential distortion, weld penetration and delta-ferrite distribution in clamped tungsten inert gas welded butt joint of 316 stainless steel

Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

Experimental Investigation on Residual Stress Distribution and Relaxation Effect at Double-Side Welded Rib-to-Deck Joints of Orthotropic Steel Decks

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