Welding Of Titanium Research Articles

Effect of external magnetic field on microstructures and mechanical properties of Ti-2Al-1.5Mn titanium alloy resistance spot welds

The excellent specific strength and elevated-temperature mechanical properties make titanium alloys essential structural materials in aerospace. Resistance spot welding (RSW) has high efficiency and cost-effective and is widely used in titanium joining. However, the exceeded welding penetration and coarse martensite α′ limit the mechanical properties of titanium welds. This paper implemented an external magnetic field (EMF) in the RSW process of Ti-2Al-1.5Mn titanium alloy, with detailed investigations into microstructure and mechanical properties. It was found that the penetration rate was reduced, and the nugget diameter was increased under the EMF. Moreover, the coarser columnar prior β grains (PBGs) and martensite α′ formed in traditional RSW transformed into the equiaxed PBGs and widmannstatten structure with α colonies. Due to the significantly improved microstructure and larger nugget diameter, the lap-shear properties were also improved.

Effect of Quenching and Aging on the Microstructure and Mechanical Properties of Welded Joints Obtained by Laser Welding of Titanium and Aluminum Alloys

Effect of Quenching and Aging on the Microstructure and Mechanical Properties of Welded Joints Obtained by Laser Welding of Titanium and Aluminum Alloys

Coupling influence of laser-Nb interlayer on microstructure and performance of Ti/Al joint

Laser fusion welding of TC4 titanium (Ti) alloy and aviation 7075 aluminum (Al) alloy was conducted with the assistance of a niobium (Nb) interlayer. The effect of laser heat input and the alloying effect of Nb on the interfacial layer was analyzed. The study also investigated the coupling influence of the laser-Nb interlayer on the microstructure and performance of the Ti/Al joint. By utilizing a 0.1 mm-thick Nb interlayer and a welding velocity of 1800 mm/min, the results reveal an initial increase in tensile-shear force followed by a decline with the increase of laser power. The tensile-shear force reached a peak of 1663 N at 1.2 kW, representing a 36.76 % improvement over the 1 kW levels. Under appropriate laser power, the enhancement in joint performance is dominated by the controlled heat input and the effective Nb-alloying effect, which reduce the thickness and brittleness of the interfacial intermetallic layer, respectively. However, metallurgical regulation of Nb will be restricted by the insufficient Nb melting amount resulting from the low laser power, leading to a decrease in joint properties. Excessive laser power can lead to the formation of hot cracks and an excessive amount of Ti-Al intermetallic compounds, which can decrease the Nb content, thereby restricting the metallurgical regulation of Nb and the overall joint performance.

Improving interfacial strength at room and elevated temperatures in ultrasonic welding of pure titanium: Interlayer-induced phase transformation and concentrated plastic deformation

Ultrasonic welding (USW) of Titanium (Ti) sheets presents several challenges, notably crack formation due to sliding friction. To overcome this problem, the present study applied USW to pure α-Ti sheets both with and without different interlayer metals (Al, Ni, and Fe). Al interlayer improved the strength at room temperature significantly to cause base metal fracture (1700 N) by inducing concentrated plastic deformation, facilitating bonding with Ti while minimizing damage. However, its strength decreased significantly at 150–300 °C, suggesting the limitation of using Al interlayer at elevated temperatures. Conversely, the Ni and Fe interlayers led to a two-phase strength development. This enhancement was due to β-phase transformation, which reduces the interfacial defects and generates a more pronounced β-stabilization effect. The Ni interlayer, which has a higher β-transus point (765 °C) and lower molybdenum equivalency, required a higher welding energy (1800 J) and longer diffusion time into Ti, resulting in a gradual increase in strength due to a slower β-Ti transformation. On the other hand, the Fe interlayer with a lower β-transus point relative to Ti (595 °C) achieved peak strength at a lower welding energy of 1200 J. Both Fe and Ni interlayers displayed only a slight decrease in strength (1500–1600 N) at 300 °C with base metal fracture, revealing better joint performance at higher temperatures. These insights suggest a strategical interlayer selection based on the operation temperature, where Al interlayers were advantageous for low-energy welding at room temperature application, Fe and Ni interlayers offer sufficient strength at elevated temperatures by facilitating the β-Ti formation.

THE EFFECT OF LASER OSCILLATING WELDING ON FORMATION AND PROPERTIES OF TITANIUM ALLOY

Titanium alloys are widely used in aerospace and other fields due to their advantages of low density, high specific strength and good corrosion resistance. Laser oscillating welding is an innovative process in the realm of welding technology. In this study, two laser oscillating welding methods (circular and linear) were employed to analyze the influence of different oscillation parameters on the formation of titanium alloy. The results indicate that the oscillation frequency has a significant impact on weld formation. The laser scanning trajectory also affects weld formation, with circular and linear scanning trajectories resulting in better weld quality. Finally, the effects of oscillation modes on the microstructure and properties of laser oscillating welding titanium alloy were investigated based on optimized process parameters. Among them, circular laser oscillating welding of titanium alloy exhibits higher tensile strength, with a maximum tensile strength of up to 1188.3[Formula: see text]MPa.

Ultrashort pulse laser welding of alumina ceramic and titanium

The direct welding of alumina ceramic and titanium using ultrashort pulse laser was successfully achieved for the first time. Benefitting from the extremely high peak power of ultrashort pulse laser, ceramics can be melted at a very low laser power. The emerging welding method was conducted at room-temperature without the need for preheating. Within the joint, a combination of Ti and Al elements was observed. A newly formed TiO2 phase was identified at the Al2O3/welding seam interface. Under the optimal welding parameters (welding speed: 0.8mm/s, laser power: 19.52W), the joint achieved a maximum four-point bending strength of approximately 134.9MPa. This study proposed a new methodology for butt welding of ceramics and metals and shows a much higher efficiency than the commonly used ceramic-metal joining approaches such as brazing and diffusion bonding.

Weld formation and porosity in TC4 joint by oscillating laser beam welding with circle trajectory model

The pores problem is a challenging problem in laser beam welding titanium alloy TC4. Oscillating laser beam welding, as a new welding process, can effectively control the behavior of the molten pool, and is beneficial to the escape of pores, which holds promise for achieving high quality TC4 joint. Selecting appropriate oscillation parameters is the key to obtaining high quality TC4 joint by LBW. This project will focus on researching the effects of oscillating parameters on weld formation and porosity of TC4 joint by oscillating laser beam welding. Firstly, the oscillating laser beam welding experimental platform was set up, and experiments on oscillating LBW were designed and conducted. Subsequently, the microstructure of TC4 joint was analyzed, and the effects of oscillating frequency and oscillating amplitude on weld formation were studied, and the effects of oscillating frequency and oscillating amplitude on porosity were researched. The results indicate that oscillating laser beam welding with circle trajectory model can achieve high quality TC4 joint. The porosity of weld by oscillating LBW with oscillation amplitude as 1 mm and oscillating frequency as 80 Hz reaches 0.13% in value which is the lowest among the experiment cases under the condition as fixing the oscillation amplitude 1 mm in value and varying the oscillation frequency from 40 Hz to 240 Hz. When the oscillation amplitude exceeds the critical value 2.5 mm, the weld by oscillating LBW exhibits noticeable undercutting and asymmetry. The undercutting occurs on the advancing side in oscillating LBW with circle trajectory model. To a certain extent this study enriches the theory of oscillating LBW, and can provide fundamental data for oscillating laser beam welding on TC4.

Electron-Beam Welding of Titanium and Ti6Al4V Using Magnetron-Sputtered Nb, V, and Cu Fillers

In this work, the results of an investigation of electron-beam-welded samples of commercially pure titanium (CP-Ti) and the titanium alloy Ti6Al4V (Ti64) using fillers of various beta-stabilizing elements (Nb, V, Cu) are presented. The fillers were in the form of deposited layers on each of the two specimens via DC magnetron sputtering. The specimens were then subjected to electron-beam welding (EBW) under the same technological conditions. The structure of the obtained welded joints was investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD) was used to investigate the phase composition of the fusion zone (FZ). The study of the mechanical properties of the samples was carried out via tensile tests and microhardness measurements. The results showed a different influence of the used fillers on the structure and properties of the obtained joints, and in all cases, the yield strength increased compared to the samples welded using the same technological conditions without the use of filler material. In the case of using Nb and V as a filler, the typical transformation of titanium welds into elongated αTi particles along with α’-Ti martensitic structures was observed. The addition of a Cu filler into the structure of the welds resulted in a unification and refining of the structure of the last, which resulted in the improvement of the mechanical properties of the weld, particularly its ductility, which is a known issue where electron-beam welding is concerned.

Effect of interlayer materials on microstructure, hardness and corrosion resistance of an electromagnetic welded titanium–stainless steel interface

Effect of interlayer materials on microstructure, hardness and corrosion resistance of an electromagnetic welded titanium–stainless steel interface

Structure and mechanical properties of three-layer composites obtained by magnetic pulse welding of titanium and Zr-based metallic glass

Structure and mechanical properties of three-layer composites obtained by magnetic pulse welding of titanium and Zr-based metallic glass

Mechanical and fatigue resistance of restorations supported by welded-framework and realized using computer-aided designed prosthetic shells: In vitro pilot study.

Resin coating in implants rehabilitation cannot always be aesthetic, durable and comfortable for the patient mainly due to the limited dimensions of the final structure. Intraoral welding technique and computer-aided designed prosthetic shells may be a solution. This in vitro study evaluates the capacity of load and the weakest point of implant-supported provisional prosthesis using welded titanium framework. Twelve samples were produced to simulate an implant supported fixed prosthetic bridge. Two implants (Ankylos; Dentsply Sirona Implants; Germany) were inserted inside blocks of nanoceramic material produced with a stereolithographic 3D printer. A polymethylmethacrylate (PMMA) resin shell was performed with CAD/CAM and relined on welded framework. Six samples were produced with the same procedure reducing resin thickness. The samples were subjected to fatigue test (6,500,000 cycles) using ElectroForce 3310 fatigue machine (t1); subsequently a mechanical compression test using a universal Shimadzu AGS-X 10 machine (t2). The samples were analyzed with a photographic and radiographic documentation at t0, t1 and t2. The samples survived mechanical fatigue test without evidence of failure. The radiographic and photographic evaluation revealed the fracture of resin coating after the mechanical compression test. The samples with minimal resin thickness fractured first. Adequate assessment of the resin thickness is mandatory to improve the longevity of these rehabilitations. CAD-CAM digital prosthetic design allows us to optimize the thicknesses and the prosthetic shapes, allowing us to obtain good degrees of resistance even in the presence of reduced prosthetic spaces.

Effect of Electron Beam Oscillation Welding of Molybdenum and Titanium

Electron beam welding of pure molybdenum (Mo) and titanium alloy (Ti-6Al-4V) was performed with beam oscillation. The effects of beam oscillation with offset on the welded joints were analyzed in terms of microstructure, element distribution, chemical composition, microhardness, and tensile strength. The results showed that the fusion zone expanded with beam oscillation. Reaction layers were generated in both joints welded with and without beam oscillation. The thickness of the reaction layers decreased along the perpendicular direction. The reaction layers were (Mo, Ti) solid solutions. Both welded joints consisted of single-phase Mo, the β-Ti phase, and Mo-Ti solid solutions. The microhardness distribution of the joint welded with beam oscillation was more consistent than that of the joint welded without beam oscillation, and the maximum hardness was reduced from 340 HV to 270 HV. The tensile strength increased from 124 MPa to 204 MPa.

ВЛИЯНИЕ ТЕРМИЧЕСКИХ УСЛОВИЙ ПРИ СВАРКЕ ВЗРЫВОМ ТИТАНА С АЛЮМИНИЕВО-МАГНИЕВЫМ СПЛАВОМ

The article presents the results of experiments on explosion welding of titanium with aluminum-magnesium alloys with preheating and cooling of a fixed plate, and also shows the features of the destruction of joints.

Determining the pattern of direction and distribution of intermetallic phase in the eutectic of the weld material after electron-beam welding of titanium and niobium alloys

This paper reports a study whose object was material of the weld. The nature of changes in the microstructure of the weld material, which are caused by changes in the supplied energy, alloying elements and heat removal from the melt area, was investigated. Welding was performed with an electron beam at Uacc=60 kV, Ieb=90 mA, with an elliptical sweep of 3×4 mm. The speed of electron beam movement veb was varied from 7 to 15 mm·s-1. The temperature of the experimental welded samples T0 was varied from 300 K to 673 K. Ti-TiB alloy (a microcomposite alloy with reinforcing TiB fibers) was welded with Ti-TiB alloys, T110, and with niobium. One of the tasks of welding this alloy was to preserve and optimize the structure of this type in the weld. Grinding of boride fibers, loss of their initial orientation, and formation of a dendritic or cellular microstructure was observed in the weld. Using the methods of raster electron microscopy and micro-X-ray spectral analysis, the microstructure of the weld material was investigated and the dimensional characteristics of TiB fibers under different welding conditions were determined. The analysis of changes in the microstructure of the weld material, the average length ᶏ and the thickness ȩ of the boride fibers in the material of the joints made at different velocities of electron beam movement and initial temperatures T0 was carried out. It was established that the growth of the ratio ȩ/ᶏ from 0.04–0.07 to 0.1–0.27 is accompanied by significant changes in the microstructure and the mechanism of formation of eutectic phases. It is shown that the process that determines the formation of the microstructure of the weld material was the eutectic breakdown with the determining influence of the temperature gradient, crystallization rate, supercooling, concentration inhomogeneities, and alloying impurities.

Study of melt pool dynamics and porosity forming mechanism of laser beam oscillation welding of titanium and aluminum

In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Three oscillation paths, namely, straight, sine, and circular, are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of the fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by using the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding circular path. Notably, numerical simulation results are validated through experimental data, and circular oscillating laser welding significantly reduced weld seam porosity in the welding of Ti–Al dissimilar alloys. The circular oscillation path with an offset of 0.6 mm and an oscillation amplitude of 0.6 mm is identified as the optimal approach for suppressing pores in the weld joint. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.

Joining mechanism evolution of fusion welded TC4 titanium alloy/304 stainless steel dissimilar joint by GTAW

Gas tungsten arc welding with a pure Cu filler wire was carried out to join the TC4 titanium alloy and 304 stainless steel. Filling pure Cu filler wire assisted with regulating welding current could effectively restrain the concentrated generation of Ti–Fe brittle intermetallic compounds. Three joining modes exist in the fusion welding titanium alloy and stainless steel. In the partial fusion welding mode, the TiCu phase decreased and the fine granular τ2 phase formed in the Ti/Cu interfacial zone, simultaneously, the molten zone consisted of a Cu solid solution and α-(Fe, Cr) phase formed at the Cu/Fe interface, resulting in mechanical interlocking effect and consequent high tensile strength of 363 MPa. Increasing the welding current would lead to the alloying of Ti x Cu y phases, and then enhance the Ti/Cu interface.

Dissimilar Laser Beam Welding of Titanium to Stainless Steel Using Pure Niobium as Filler Material in Lap Joint Configuration

In the present investigation, commercially pure titanium is welded to AISI 316L stainless steel by intermixing niobium as filler material in a lap joint configuration. For this purpose, a pulsed Nd:YAG laser with various pulse durations and pulse peak powers is employed to obtain different mixing conditions for the materials. It will be demonstrated that, despite the implementation of the filler material, the weld seams are characterized by a high affinity for cracking, which in turn can be attributed to the formation of hard intermetallic compounds. Nevertheless, utilization of optimized process parameters can yield crack-free specimens in a reproducible manner through equable intermixing of otherwise critical alloy elements. Lap-shear forces of up to 140 N can be achieved with a single weld seam measuring 2.5 mm in length. By increasing the joint area with four adjacent weld seams, maximum loads up to 320 N are attained, thus exceeding the yield strength of the applied stainless steel. Considering the biocompatibility of the niobium filler material used, this work provides the foundation for this dissimilar material combination to be implemented in future medical technology applications.

Mechanism of microstructure evolution and improved mechanical properties in two-pass friction stir welding of titanium to aluminum

Mechanism of microstructure evolution and improved mechanical properties in two-pass friction stir welding of titanium to aluminum

Influence of High-Temperature Annealing on Microstructure and Properties of Welded Joints Using Narrow Gap Laser Welding of TC4 Titanium with Welding Wire

Influence of High-Temperature Annealing on Microstructure and Properties of Welded Joints Using Narrow Gap Laser Welding of TC4 Titanium with Welding Wire

Electron beam welding of dissimilar Titanium to aluminium: Interface microstructure and mechanical properties

Welding of dissimilar metals, titanium–aluminium having wide differences in mechanical and thermal properties was highly challenging. In the present investigation, the electron beam welding method was used to join titanium alloy with pure aluminium. The results show that at the optimum parameter levels such as beam current of 6 mA, welding speed of 8 mm/s, and beam offset of 70:30 (Ti:Al) toward titanium, a defect-free joint with the higher mechanical strength of 120 MPa was achieved compared to the other combination of parameters. The percentage contribution of significant parameters was welding speed of 62%, and beam current of 25%. The scanning electron microscope was used to study the Ti–Al interface microstructure in detail. A significant increase in the micro-hardness in the weld zone was due to a change in titanium microstructure from equiaxed α-phase to acicular α and the formation of Ti-Al intermetallics in the fusion zone. X-ray diffraction analysis was used to analyze the phases present in the fusion zone. It was confirmed that there were mainly Al-Ti compounds like Al2Ti, Al3Ti, AlTi, AlTi2, Al11Ti5. These phases are harmful and contributed to higher hardness and brittleness in the fusion zone. At optimum conditions, a defect-free joint without intermetallics was obtained without an increase in hardness in the fusion zone.