Microstructure, mechanical properties and residual stress distribution in pulsed tungsten inert gas welding of Ti–5Al–2.5Sn alloy

2018 ◽  
Vol 233 (10) ◽  
pp. 2030-2044
Author(s):  
Massab Junaid ◽  
Fahd Nawaz Khan ◽  
Muhammad Rashid Mirza ◽  
Mirza Nadeem Baig
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fusion Zone ◽  
Weld Line ◽  
Alloy Sheet ◽  
Inert Gas ◽  
Hardness Profile ◽  
Micro Hardness ◽  
Tungsten Inert Gas Welding ◽  
Zone Width

Pulsed tungsten inert gas welding with full penetration was performed on 1.6 mm thick Ti–5Al–2.5Sn alloy sheet. Hole-drill strain measurement method was employed to measure the distribution of residual stresses across the weld line. Tensile tests were performed on the specimens sectioned in transverse direction of the welded sample. The evolved microstructure in the welded zone was investigated by metallography and X-ray diffraction. Transverse residual stresses of tensile nature were present at different depths below the surface and decreased the yield strength and ultimate tensile strength. However, this decrease was not dependent on the maximum value of transverse residual stress. Fracture location was found to be dependent on the micro-hardness profile and fracture took place in base metal where micro-hardness was the lowest. Furthermore, the presence of tensile residual stresses in the welded sample had no influence on the fractured surface morphology. Peak current and background current had a significant influence on the fusion zone width, heat-affected zone width, and fusion zone grain size.

Comparison of microstructure, mechanical properties, and residual stresses in tungsten inert gas, laser, and electron beam welding of Ti–5Al–2.5Sn titanium alloy

2017 ◽  
Vol 233 (7) ◽  
pp. 1336-1351
Author(s):  
Massab Junaid ◽  
Khalid Rahman ◽  
Fahd Nawaz Khan ◽  
Nabi Bakhsh ◽  
Mirza Nadeem Baig
Keyword(s):  
Electron Beam ◽  
Residual Stresses ◽  
Power Density ◽  
Fusion Zone ◽  
High Power ◽  
Electron Beam Welding ◽  
Inert Gas ◽  
High Power Density ◽  
Cooling Rates ◽  
Zone Width

Electron beam welding (EBW), pulsed Nd:YAG laser beam welding (P-LBW), and pulsed tungsten inert gas (P-TIG) welding of Ti–5Al–2.5Sn alloy were performed in order to prepare full penetration weldments. Owing to relatively high power density of EBW and LBW, the fusion zone width of EBW weldment was approximately equal to P-LBW weldment. The absence of shielding gas due to vacuum environment in EBW was beneficial to the joint quality (low oxide contents). However, less cooling rates were achieved compared to P-LBW as an increase in heat-affected zone width and partial α′ martensitic transformation in fusion zone were observed in EBW weldments. The microstructure in fusion zone in both the EBW and P-TIG weldments comprised of both acicular α and α′ martensite within the prior β grains. Hardness of the fusion zone in EBW was higher than the fusion zone of P-TIG but less than the fusion zone of P-LBW weldments due to the observed microstructural differences. Notch tensile specimen of P-LBW showed higher load capacity, ductility and absorbed energy as compared to P-TIG and EBW specimens due to the presence of high strength α′ martensite phase. Maximum sheet distortions and tensile residual stresses were observed in P-TIG weldments due to high overall heat input. The lowest residual stresses were found in P-LBW weldments, which were tensile in nature. This was owing to high power density and higher cooling rates in P-LBW operation. EBW weldment exhibited the highest compressive residual stresses due to which the service life of EBW weldment is expected to improve.

scholarly journals On mechanical and morphological investigations of tungsten inert gas welded SS 304 thin pipe joints

2020 ◽  
Vol 53 (1-2) ◽  
pp. 61-72 ◽  
Author(s):  
Hitesh Arora ◽  
Rupinder Singh ◽  
Gurinder Singh Brar
Keyword(s):  
Residual Stresses ◽  
Heat Affected Zone ◽  
Welding Speed ◽  
Welding Current ◽  
Weld Bead ◽  
Inert Gas ◽  
Micro Hardness ◽  
Tungsten Inert Gas Welding ◽  
Pipe Joints ◽  
Ss 304

Tungsten inert gas welding is one of the established joining processes for stainless steel. But hitherto very little has been reported on induced residual stresses in circular thin pipe joints during tungsten inert gas welding of SS 304. This paper reports the effect of welding parameters such as welding speed, welding current and shielding gas flow rate of tungsten inert gas welding on micro-hardness, width of the heat-affected zone, residual stresses and microstructural properties of SS 304 thin pipe joints. The results indicate that the welding current and the welding speed have a significant effect on micro-hardness of weld bead and width of the heat-affected zone. Further changes in the microstructure of the joints were studied in terms of dendrite formation. It has been observed that there is proportional increase in depth/width of the heat-affected zone with the heat input during the joining process, resulting in a decrease of micro-hardness. The results are also supported by radiographic analysis and X-ray diffraction data to understand the nature of residual stresses which was observed as compressive at the weld bead and tensile along the axis of thin welded pipe joints. Finally, the process capability analysis based on Cp and Cpk values of ≥1 suggests that the process can be gainfully used for mass production.

Experimental Study on Residual Stresses of Al2O3 Coating by Laser Re-Melting

2010 ◽  
Vol 431-432 ◽  
pp. 446-449
Author(s):  
De Jun Kong ◽  
Kai Yu Luo ◽  
Hong Miao
Keyword(s):  
Residual Stress ◽  
Experimental Study ◽  
Tensile Stress ◽  
Residual Stresses ◽  
High Power ◽  
Bonding Strength ◽  
Strengthening Mechanism ◽  
Al2o3 Coating ◽  
Micro Hardness ◽  
Continuous Co2 Laser

The surface of Al2O3 coating sprayed on 40Cr substrate was re-melted with high power continuous CO2 laser, and its micro-hardness and residual stresses were measured, respectively. The strengthening mechanism of Al2O3 coating by laser re-melting was analyzed and discussed. The experimental results shown that the surface of Al2O3 coating by laser re-melting is neat and smooth, and its compositions are even, its structures are compact, and Al2O3 coating is evenly distributed in its surface with grain forms, and its micro-hardness increases about 200%; Residual stress of Al2O3 coating by laser re-melting is changed into compressive stress from tensile stress, which is benefit to improving bonding strength of coating-substrate interface.

Review of Wire Arc Additive Manufacturing for 3D Metal Printing

2019 ◽  
Vol 13 (3) ◽  
pp. 346-353 ◽  
Author(s):  
Johnnieew Zhong Li ◽  
Mohd Rizal Alkahari ◽  
Nor Ana Binti Rosli ◽  
Rafidah Hasan ◽  
Mohd Nizam Sudin ◽  
...  
Keyword(s):  
Residual Stress ◽  
Arc Welding ◽  
Inert Gas ◽  
Plasma Arc Welding ◽  
Heat Sources ◽  
Plasma Arc ◽  
Tungsten Inert Gas Welding ◽  
Metal Printing ◽  
3D Metal Printing ◽  
Wire Arc Additive Manufacturing

Wire arc additive manufacturing (WAAM) is a crucial technique in the fabrication of 3D metallic structures. It is increasingly being used worldwide to reduce costs and time. Generally, AM technology is used to overcome the limitations of traditional subtractive manufacturing (SM) for fabricating large-scale components with lower buy-to-fly ratios. There are three heat sources commonly used in WAAM: metal inert gas welding (MIG), tungsten inert gas welding (TIG), and plasma arc welding (PAW). MIG is easier and more convenient than TIG and PAW because it uses a continuous wire spool with the welding torch. Unlike MIG, tungsten inert gas welding (TIG) and plasma arc welding (PAW) need an external wire feed machine to supply the additive materials. WAAM is gaining popularity in the fabrication of 3D metal components, but the process is hard to control due to its inherent residual stress and distortion, which are generated by the high thermal input from its heat sources. Distortion and residual stress are always a challenge for WAAM because they can affect the component’s geometric accuracy and drastically degrade the mechanical properties of the components. In this paper, wire-based and wire arc technology processes for 3D metal printing, including their advantages and limitations are reviewed. The optimization parametric study and modification of WAAM to reduce both residual stress and distortion are tabulated, summarized, and discussed.

A Study of Residual Stresses and Microstructure in 2024-T3 Aluminum Friction Stir Butt Welds

2002 ◽  
Vol 124 (2) ◽  
pp. 215-221 ◽  
Author(s):  
M. A. Sutton ◽  
A. P. Reynolds ◽  
D.-Q. Wang ◽  
C. R. Hubbard
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Weld Line ◽  
Free Edge ◽  
Two Dimensions ◽  
Grain Structure ◽  
Friction Stir ◽  
Shoulder Diameter ◽  
Shoulder Region

Three-dimensional residual stress mapping of an aluminum 2024-T3 arcan specimen, butt-welded by the friction stir technique, was performed by neutron diffraction. Results indicate that the residual stress distribution profiles across the weld region are asymmetric with respect to the weld centerline, with the largest gradients in the measured residual stress components occurring on the advancing side of the weld, with the longitudinal stress, σL, oriented along the weld line, as the largest stress. Within the region inside the shoulder diameter, the through-thickness stress, σZ, is entirely compressive, with large gradients occurring along the transverse direction just beyond the shoulder region. In addition, results indicate a significant reduction in the observed residual stresses for a transverse section that was somewhat closer to the free edge of an Arcan specimen. Microstructural studies indicate that the grain size in the weld nugget, is approximately 6.4 microns, with the maximum extent of the recrystallized zone extending to 6 mm on each side of the weld centerline. Outside of this region, the plate material has an unrecrystallized grain structure that consists of pancake shaped grains ranging up to several mm in size in two dimensions and 10 microns in through-thickness dimension.

Tungsten Inert Gas (TIG) Cladding of TiC-Fe Metal Matrix Composite Coating on AISI 1020 Steel Substrate

2020 ◽  
Vol 1159 ◽  
pp. 19-26
Author(s):  
Anil Kumar Das ◽  
Sujeet Kumar ◽  
Mayank Kumar Chaubey ◽  
Waquar Alam
Keyword(s):  
Composite Coating ◽  
Gas Flow ◽  
Steel Substrate ◽  
Variable Parameter ◽  
Scanning Speed ◽  
Inert Gas ◽  
Hardness Profile ◽  
Micro Hardness ◽  
Gas Flow Rate ◽  
Hardness Tester

TiC – Fe composite coating was produced on AISI 1020 steel by the tungsten inert gas (TIG) cladding process to increase the hardness and wear resistance properties of the substrate. In this paper authors have investigated the effect of process parameters on the microstructure and hardness value of the coated layer. In this TIG cladding process the variable parameter is only current, whereas the other parameters such as scanning speed, standoff distance, and voltage and gas flow rate are fixed. Fe and TiC powders were mixed in the proper ratio of 80wt% - 20wt% and 90wt% - 10wt% respectively. The microstructure and micro-hardness value of the samples were investigated by the scanning electron microscope (SEM) and Vickers micro hardness tester. The result of SEM shows the distribution of the coating powder in the cladded zone. Micro hardness profile shows the variation of the hardness value in the cladded zone as well as in the substrate. The hardness value decreases with increase in distance from top surface of the cladded layer, which is due to difference in cooling rate. Also, the hardness value of cladded layer decreases with increase in current from 140A to 150A. The maximum hardness value of cladded layer was achieved as 262 HV0.05 with 140A current and composition of 90 wt.% - 10wt% (Fe - TiC), which was nearly two times higher than that of the as received AISI 1020 steel substrate. Keywords TIG, Microstructure, Micro hardness, Titanium Carbide (TiC), Iron (Fe) powder.

Effect of the interpass temperature on the predicted residual stress distributions in a multipass welded piping branch junction

2008 ◽  
Vol 43 (2) ◽  
pp. 109-119 ◽  
Author(s):  
W Jiang ◽  
K Yahiaoui
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cross Sections ◽  
Branch Pipe ◽  
Three Dimensional ◽  
Weld Line ◽  
Element Model ◽  
Stress Distributions ◽  
Inner Surface ◽  
Interpass Temperature

A sequentially coupled three‐dimensional thermomechanical finite element model has been developed to predict residual stress distributions in a multipass welded piping branch junction. The residual stresses at the branch and run pipe cross‐sections, as well as along the circumferential weldlines on the outer surfaces of both the run and the branch pipes and on the inner surface of the branch pipe, are predicted. Three levels of interpass temperature have been selected to investigate their effect on the peak residual stresses. It is revealed that the interpass temperature has a significant effect on the residual stresses. As the interpass temperature is increased, both the peak hoop and the axial residual stresses at the run and branch cross‐sections decrease. The peak normal stresses along the circumferential weldline on the outer surface of the run pipes are also reduced. However, increasing the interpass temperature had a negligible effect on the peak tangential residual stresses along the circumferential weld line on the inner surface of the branch pipe. The results presented and the modelling technique described in the current study can be used towards formulating a recommendation to optimize residual stress profiles in multipass welded complex geometries through better interpass temperature control.

The influence of process parameters on the distribution of residual stresses in magnetically impelled arc welded joints

2018 ◽  
Vol 233 (11) ◽  
pp. 3936-3949
Author(s):  
M Sedighi ◽  
J MosayebNezhad
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Phase Change ◽  
Welded Joints ◽  
Weld Line ◽  
Element Model ◽  
Welding Parameters ◽  
Welding Time ◽  
Contributing Factors ◽  
Influence Of Process Parameters

In this study, the influence of welding parameters on the distribution of residual stress in magnetically impelled arc butt welded joints was investigated. As major contributing factors to the quality of weldments and residual stress, welding time and welding upsetting pressure were focal points of this work. Experimentally verified thermal-metallurgical and mechanical finite element model was used for conducting this purpose. The effects of phase change including volumetric phase change and transformation plasticity were considered in the numerical model. Based on the numerical simulation it was observed that for instance by increasing upset pressure from 0 to 130 MPa, axial residual stresses have reduced from −210 MPa to −119 MPa, while by increasing welding time from 4 to 6 s, these stresses have increased from −119 MPa to −138 MPa on the outer surface of the weld line.

Laser Surface Hardening of Steel: Effect of Process Atmosphere on the Microstructure and Residual Stresses

2013 ◽  
Vol 772 ◽  
pp. 149-153 ◽  
Author(s):  
Vladimir Kostov ◽  
Jens Gibmeier ◽  
Alexander Wanner
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Surface Hardening ◽  
Local Heating ◽  
Laser Surface ◽  
Inert Gas ◽  
X Ray ◽  
Depth Direction ◽  
Laser Surface Hardening ◽  
Gas Atmosphere

The effect of processing atmosphere on the microstructure and residual stresses are studied for laser surface hardening on steel samples of grade AISI 4140. Samples were hardened in air, vacuum and inert gas atmosphere (Helium) by means of a stationary laser beam. A high-power diode laser (HPDL) system was used in combination with a custom-designed process chamber. Residual stress distributions in lateral and in depth direction were analysed after laser processing by means of X-ray diffraction according to the well known sin² - method. X-ray residual stress analyses were supplemented by microscopic investigations of the local microstructure. The results indicate a widening of the compressive stressed region in lateral as well as in depth direction by surface hardening in inert gas atmosphere compared to laser surface hardening in air or vacuum atmosphere. This is due to the local heating flux distribution during the laser assisted heat treatment which is strongly affected by the processing atmosphere an leads to an extension of the hardening zone when using helium as inert gas.

Influence of filler material on the microstructure, mechanical properties, and residual stresses in tungsten inert gas welded Ti-5Al-2.5Sn alloy joints

2021 ◽  
pp. 146442072110124
Author(s):  
Asim Iltaf ◽  
Fahd Nawaz Khan ◽  
Tauheed Shehbaz ◽  
Massab Junaid
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Fusion Zone ◽  
Welded Joint ◽  
Weld Zone ◽  
Martensitic Transformations ◽  
Inert Gas ◽  
Physical Chemical ◽  
Pile Up ◽  
Compressive Residual Stresses

The microstructure and defects in the weld zone affect the weldment characteristics. One way to improve the microstructure and reduce the defects in the weld zone is by using a filler during welding which influences the physical, chemical, and mechanical properties of the manufactured component. In the present study, tungsten inert gas (TIG) was used to weld Ti-5Al-2.5Sn alloy using different titanium alloy fillers; Ti-6Al-4V, Ti-5Al-2.5Sn, and autogenous weldments were also produced. The welded joints were characterized in terms of their microstructure, mechanical properties, and residual stresses in its various regions. The weldment with Ti-6Al-4V as filler exhibited a higher proportion of α′ martensite in fusion zone, as compared to the welded joint with Ti-5Al-2.5Sn alloy as filler, owing to the higher proportions of β stabilizers present in Ti-6Al-4V alloy. The α’ martensite was present in basketweave and acicular morphology in all the weldments, with and without fillers. Ti-6Al-4V filler welded joint showed higher tensile strength (approximately 1144 MPa) and relatively higher hardness than Ti-5Al-2.5Sn filler welded joint (approximately 1027 MPa) and autogenous weldment (approximately 770 MPa), due to increased amount of martensite in its fusion zone. As compared to the weldment produced with Ti-5Al-2.5Sn filler, the welded joint produced without filler and with Ti-6Al-4V as a filler had more compressive residual stresses at surface (approximately 25% higher), leading to less amount of pile up after nanoindentation. This was attributed to the generation of compressive strains due to martensitic transformations in the fusion zone of both these weldments.

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