Influence of electron beam oscillation patterns on the microstructure, texture, residual stress and mechanical properties of Ti-5Al-2.5Sn alloy weldments

2020 ◽  
pp. 095440542093753
Author(s):  
Asim Iltaf ◽  
Massab Junaid ◽  
Fahd Nawaz Khan ◽  
Nabi Bakhsh ◽  
Muftooh Ur Rehman
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Residual Stresses ◽  
Fusion Zone ◽  
Electron Beam Welding ◽  
Physical Phenomenon ◽  
Weld Zone ◽  
Rectangular Pattern ◽  
Rectangular Waveform ◽  
Beam Oscillation

Vacuum electron beam welding is widely employed for the welding of titanium alloys using different beam oscillation patterns. Since these patterns influence the physical phenomenon in the weld pool, its effect on the microstructure, texture, mechanical properties and residual stresses is of prime interest. In order to understand this influence, electron beam welding was used to prepare Ti-5Al-2.5Sn weldments using beam oscillations of triangular and rectangular waveform. It was observed that a change of welding pattern had a strong influence on the residual stresses, impact properties and texture of weld zone while tensile properties were not significantly affected. A partial martensitic transformation was observed in both the triangular and rectangular waveform of oscillations. An increase in alpha lathe width was observed in the fusion zone and similar strength of the rectangular pattern as compared to triangular pattern. Despite of this, the observed higher Vickers hardness of the fusion zone of rectangular pattern as compared to triangular and no-oscillation was attributed to texture strengthening using rectangular waveform.

Microstructure, mechanical properties, residual stresses and texture analysis of Ti-5Al-2.5Sn alloy weldments obtained using electron beam of different oscillation patterns

2020 ◽  
Vol 234 (17) ◽  
pp. 3484-3496
Author(s):  
Asim Iltaf ◽  
Massab Junaid ◽  
Fahd N khan ◽  
Azhar Hussain
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Residual Stresses ◽  
Fusion Zone ◽  
Electron Beam Welding ◽  
Stress Measurement ◽  
Concentric Circle ◽  
Impact Testing ◽  
Circle Patterns ◽  
Concentric Circles

Electron beam welding was used for welding of Ti-5Al-2.5Sn alloy using three types of beam oscillation patterns, i.e. elliptical, concentric circles and arrow shape waveform. The influence of these patterns on microstructure, mechanical properties and residual stresses was investigated using optical microscopy, electron back scattered diffraction, scanning electron microscopy, microhardness measurement, residual stress measurement, impact testing, smooth and notch tensile testing. A partial martensitic transformation was observed in the fusion zone of all the three welding patterns. The fusion zone of arrow pattern weldment exhibited approximately 16% and 1.2% higher hardness than elliptical and concentric circles patterns, respectively. Owing to an improved texture of the basal and prismatic planes in the cross-weld direction, the arrow pattern showed improved strength, reduced tensile residual stresses than elliptical and concentric circles pattern. Elliptical pattern showed superior elongation characteristics as well as increased impact strength as compared to the arrow and concentric circle patterns.

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.

Mechanical Properties of Forged Ti-6Al-4V Structure by Electron Beam Welding

2012 ◽  
Vol 455-456 ◽  
pp. 308-313
Author(s):  
Hong Yu Qi ◽  
Jian Xie ◽  
Shao Lin Li ◽  
Xiao Guang Yang
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Fusion Zone ◽  
Electron Beam Welding ◽  
Welded Joint ◽  
Base Material ◽  
Structure Design ◽  
Large Gradient ◽  
Welded Structure ◽  
Aero Engine

The blisk (bladed disk) is a new structural component of the modern aero-engine and plays an important role in improving its performance. Ti-6Al-4V alloy joints welded by electron beam have been widely used for compressor blisk in advanced aero engine. It is necessary to analyze microstructure and mechanical properties of Ti-6Al-4V welded structure by electron beam welding (EBW) for failure analysis and structure design of blisk. Microstructure of Ti-6Al-4V welded structure by EBW was investigated by microscopic observation and micro indentation testing. Experiment results show grain coarsening in fusion zone (FZ) and heat affected zone (HAZ) appears large gradient organization structure, which presents significant local heterogeneity. On the centerline perpendicular to the welding direction, Vickers microhardness was measured in increments of 1mm, 0.5mm, 0.25mm and 0.1mm. Due to the presence of martensite, microhardness of the fusion zone is about 20% higher than that of the base material. The size of joints in different regions was acquired, 2.5 to 3.0-mm-wide in FZ and about 0.7-mm-wide in HAZ respectively. Three different types of EBW samples were designed for tensile test, including welded structure, welded joint and base material. Three different stress-strain curves of specimens were acquired, including welded joint. The experiment data indicates that the tensile strength of welded joints is 8% more than that of the base metal.

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.

scholarly journals Effect of post weld heat treatment on metallurgical and mechanical properties of electron beam welded AISI 409 ferritic steel

10.30544/545 ◽  
2020 ◽  
Vol 26 (3) ◽  
pp. 279-292
Author(s):  
Akash Doomra ◽  
Sandeep Singh Sandhu ◽  
Beant Singh
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Electron Beam ◽  
Ferritic Stainless Steel ◽  
Electron Beam Welding ◽  
Weld Zone ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The applicability of ferritic stainless steel is restricted due to its low weldability, and this can be attributed to the severe grain growth in the weld zone during the solidification of the weld pool and formation of fully ferritic structure. This study aims to investigate the weldability of 18 mm thick AISI 409 ferritic stainless steel plates using an electron beam welding process without the use of filler metal. The joints were investigated for metallography characterization (microstructure, macrostructure, and microhardness) and mechanical behavior (tensile strength and impact toughness) in as-welded condition and after post-weld heat treatment at 550 ºC for 75 minutes. The weld zone exhibited large columnar grains in the direction perpendicular to the weld centerline and got refined after post-weld heat treatment. The ultimate tensile strength, yield strength, and microhardness of the weld zone were found higher than the base metal. The impact toughness of weld zone was found to be reduced by 45%, but the post-weld heat treatment improved the toughness by 40%. Results revealed that the electron beam welding process could be successfully employed for welding of AISI 409 ferritic stainless steel, which will increase its application range that requires thicker section of welded plates. Post-weld heat treatment was found to be advantageous for improving the microstructure and mechanical properties.

Microstructure and mechanical properties of 9Cr-3W-3Co steel welded joints by vacuum electron beam welding

2021 ◽  
pp. 2150192
Author(s):  
Youyi Zhang ◽  
Guoqing Gou
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
High Temperature ◽  
Base Metal ◽  
Welded Joints ◽  
Electron Beam Welding ◽  
Lath Martensite ◽  
Weld Zone ◽  
Creep Fracture ◽  
Welding Joints

This paper aims to explore the microstructure and mechanical properties of 9Cr-3W-3Co steel welded joints. In the experiment, 9Cr-3W-3Co steel samples were welded by vacuum electron beam welding technology (VEBW) without any metal stuff, and all the welding joints were treated by high-temperature tempering at [Formula: see text]C for 8 h. The microstructure of welding joints was observed by OM, SEM and TEM; and the mechanical properties of welded joints were analyzed by microhardness test, room-temperature tensile, test impact test and high-temperature creep test. As a result, all the 9Cr-3W-3Co steel samples displayed the microstructure status as martensite under the Scheffler-Schneider prediction model, which conformed to the expectation. After high-temperature tempering, the grains of the welding zone were smaller than the base metal and the composition was tempered lath martensite only. Some of the lath martensite bundles even showed the incomplete polygonal transformation. The M[Formula: see text]C6 carbides and MX phase were distributed continuously along with the lath martensite interfaces, which showed a tendency for further aggregation. The microhardness of the weld zone was slightly higher than the base metal (mean of base metal: 240 HV[Formula: see text], mean of weld zone: 273 HV[Formula: see text] and mean of heat affected area: 274 HV[Formula: see text]. There was no softening phenomenon observed, and the welding joints maintaining the high intensity. Other mechanical properties like the tensile strength (mean: 750 MPa), yield strength (mean: 707 MPa) and impact toughness (mean of WM: 25.1 J and HAZ: 23.3 J) were also excellent. When the temperature parameter is constant, the time for creep fracture reduces significantly with the increase of the stress; whereas the time for creep fracture decreases significantly as the temperature increases, while the stress parameter is constant.

scholarly journals Microstructure and Mechanical Properties of Electron Beam-Welded Joints of Titanium TC4 (Ti-6Al-4V) and Kovar (Fe-29Ni-17Co) Alloys with Cu/Nb Multi-Interlayer

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yong-jian Fang ◽  
Xiao-song Jiang ◽  
De-feng Mo ◽  
Ting-feng Song ◽  
Zhen-yi Shao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Tensile Strength ◽  
Titanium Alloy ◽  
Electron Beam ◽  
Welded Joints ◽  
Electron Beam Welding ◽  
Weld Zone ◽  
X Ray Diffraction ◽  
Strength Tests

Electron beam welding of a titanium alloy (Ti-6Al-4V) and a kovar alloy (Fe-29Ni-17Co) was performed by using a Cu/Nb multi-interlayer between them. Microstructure and composition of welded joints were analyzed by means of optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Mechanical properties of welded joints were evaluated by microhardness and tensile strength tests. Results indicated that in case of 0.22 mm thickness of Nb foil, microstructure of the titanium alloy side was mainly composed of Ti solid solution and some intermetallic compounds such as FeTi and CuTi2, whereas in case of 0.40 mm thickness of Nb foil, the appearance of weld was more uniform and hardness of the weld zone decreased sharply. However, tensile strength of welded joints was increased from 88.1 MPa for the 0.22 mm Nb foil to 150 MPa for the 0.40 mm Nb foil. It was found that thicker Nb foil could inhibit diffusion of Fe atoms towards the titanium alloy side, thus promoting the formation of Ti solid solution and a small amount of CuTi2 and eliminating FeTi. In addition, in both cases, Cu0.5Fe0.5Ti was found in the fusion zone of the titanium alloy side, which had an adverse effect on mechanical properties of welded joints.

scholarly journals Metallurgical and Mechanical Research on Dissimilar Electron Beam Welding of AISI 316L and AISI 4340

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
A. R. Sufizadeh ◽  
S. A. A. Akbari Mousavi
Keyword(s):  
Electron Beam ◽  
Electron Beam Welding ◽  
Weld Zone ◽  
Tensile Tests ◽  
Beam Current ◽  
Aisi 316L ◽  
Cooling Rates ◽  
Minimum Width ◽  
Optimum Sample ◽  
Aisi 4340

Dissimilar electron beam welding of 316L austenitic stainless steel and AISI 4340 low alloy high strength steel has been studied. Studies are focused on effect of beam current on weld geometry, optical and scanning electron microscopy, X-ray diffraction of the weld microstructures, and heat affected zone. The results showed that the increase of beam current led to increasing depths and widths of the welds. The optimum beam current was 2.8 mA which shows full penetration with minimum width. The cooling rates were calculated for optimum sample by measuring secondary dendrite arm space and the results show that high cooling rates lead to austenitic microstructure. Moreover, the metallography result shows the columnar and equiaxed austenitic microstructures in weld zone. A comparison of HAZ widths depicts the wider HAZ in the 316L side. The tensile tests results showed that the optimum sample fractured from base metal in AISI 316L side with the UTS values is much greater than the other samples. Moreover, the fractography study presents the weld cross sections with dimples resembling ductile fracture. The hardness results showed that the increase of the beam current led to the formation of a wide softening zone as HAZ in AISI 4340 side.

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