Effect Of Beam Oscillation Research Articles

Effect of Beam Oscillation on Weld Formation, Porosity, Grain Structure, and Mechanical Properties in Electron Beam Welding 5B70 Aluminum Alloy

Effect of Beam Oscillation on Weld Formation, Porosity, Grain Structure, and Mechanical Properties in Electron Beam Welding 5B70 Aluminum Alloy

Effect of beam oscillation on weld formation, microstructure and mechanical properties in vacuum laser beam welding of thick section 5083 aluminum alloy

Beam oscillation in the laser welding process has demonstrated numerous advantages in suppressing spatters, eliminating pores, and reducing gap sensitivity, particularly for joining thin plates. This study presents the welding of thick section aluminum alloy using laser beam oscillation in a vacuum environment. During vacuum laser welding, the effect of beam oscillation variables, which include oscillating path, amplitude, and frequency, on weld seam morphology, microstructures, and mechanical properties was symmetrically evaluated. The findings indicate that in a vacuum environment, beam oscillation with a small amplitude can optimize the contour of the weld sidewall and increase the penetration depth, which is different from that observed in an atmospheric environment, where the melting penetration depth decreases with increasing oscillating amplitude. The deep penetration weld seam in a vacuum environment can achieve an extremely small size of 19 ∼ 30 µm. The addition of small oscillations causes a slight increase of the average grain size. The stirring effect of beam oscillation was weakened because of the minimized weld pool size under vacuum. This increased grain size is mainly attributed to the changes in the size of the molten pool caused by the oscillation cause changes in solidification parameters which accelerate grain growth. However, increasing the oscillation frequency can greatly increase the strength of the stirring effect and the refinement ability of small-sized grains. On further increasing the oscillation frequency to 200 Hz, the grown grains are refined. The results showed the tensile strength of the vacuum laser weld joints with and without beam oscillation can achieved a value of about 90 % of the base metal, which is superior to the strength of the joints welded by atmospheric pressure laser welding and can meet the vast majority of welding needs.

Effect of beam oscillation and focusing on the electron beam welded 1100M high strength structural steel joint

The development of ultra-high-strength steels (UHSS) is revolutionizing its need in the diverse field of application, and the main credit going to the new technological advancement in the manufacturing of steels using special heat treatment like the thermomechanical rolled process to produce UHSS with up to 1300 MPa tensile strength in the thicker plate. The steel provides higher strength, toughness, and extensive reduced weight, significant in structural components and higher load lifting vehicles (e.g., mobile cranes, trailers, concrete pump trucks, etc.) with lower fuel consumption. However, welding of UHSS is also a challenge due to their higher crack susceptibility and hardness reduction in the heat-affected zone (HAZ). The study’s main objective is to analyse the effect of beam focus on the weld geometry and the different beam oscillation on the weld microstructure and hardness behaviour of the 1100M EB-welded joint. The S1100M steel samples of the thickness of 15 mm were butt-welded by autogenous electron beam welding (EBW). The study finds that UHSS can be satisfactorily welded with EBW, improving the weld geometry with beam focus. The observed results show that beam oscillation’s microstructural and hardness behaviour was attributed to developing a more uniform microstructure.

Oscillating Laser-Arc Hybrid Additive Manufacturing of AZ31 Magnesium Alloy

To overcome the instability of the traditional magnesium alloy additive process, the research on oscillating laser-arc hybrid additive manufacturing (O-LHAM) for AZ31 Mg alloy was developed first, and it focused on the effect of beam oscillation on process characteristics, such as macroscopic morphology, porosity defects, microstructure, and mechanical properties of thin-walled components. The increasing oscillation frequency was effective in suppressing the defects, including lack of fusion, wavy hump, internal porosity, etc. Compared with the case without oscillation, the average grain size of O-LHAM samples was refined from 22–32 μm to 18–20 μm at 300 Hz, while the percentage of Al8Mn5 and Mg17Al12 precipitation increased from 1.42–1.61% to 2.55–3.32%. For this reason, a stirring laminar flow was induced using the oscillating laser in the melt pool, with the ability to disrupt the grain structure and provide more nucleation sites, which is beneficial in reducing the average grain size and promoting the precipitation of the precipitated phase. Meanwhile, for the component without pores, the ultimate tensile strength is 205 MPa, slightly less than the base, but the elongation is 20.7%, twice that of the base. The tensile fracture is characterized by a large number of dimples and some ductile tearing ridges, demonstrating good ductility, which is associated with the grain refinement and precipitation strengthening induced using the oscillating laser. The results indicated that O-LHAM would be an effective method for manufacturing Mg alloy fast and well.

Effect of beam oscillation and oscillating frequency induced heat accumulation on microstructure and mechanical property in laser welding of Invar alloy

In the present work, the 3 mm thick Invar alloy butt joints are connected via circular oscillating welding. The macro appearance, microstructure morphology and mechanical property of the welded joints obtained under different oscillating frequencies are studied. The laser energy distribution is simulated to visually exhibit the range of laser radiation and the degree of energy coincidence for better explaining the formation mechanism of weld geometry. A CFD model for laser oscillating welding process is developed. The powerful vortexes induced by beam oscillation are observed which have a stirring effect on the molten pool and the heat accumulation in the weld center is much severer with increasing oscillating frequency. The influence of beam oscillation on grains around the fusion line is significant but the increase of oscillating frequency is not always beneficial for the microstructure in the weld center. For the situation with a relatively lower frequency (50 Hz), several grains are broken and smaller grain size is obtained. However, the grain refining effect caused by beam oscillation is not obvious as the frequency grows to 100 Hz. This phenomenon is ascribed to the increasing heat accumulation. The tensile test results show that the maximal tensile strength reaches 410.7 Mpa and the elongation is increased by 23.7 % compared with the non-oscillated weld when f = 50 Hz, a mass of equiaxed dimples and a small quantity of serpentine sliding are observed on the fracture surface.

Effect of Beam Oscillation on Microstructure and Tensile Property of Electron Beam-Welded Commercially Pure (CP) Titanium

Effect of Beam Oscillation on Microstructure and Tensile Property of Electron Beam-Welded Commercially Pure (CP) Titanium

Effect of beam oscillation on microstructure, defect density, and resistivity of electron beam welded niobium

Effect of beam oscillation on microstructure, defect density, and resistivity of electron beam welded niobium

Effect of beam oscillation on the mechanical properties of fiber-laser-welded thin-plate X2CrTiNb18 ferritic stainless-steel joints

This study adopted fiber laser welding (FLW) and oscillating fiber laser welding (OFLW) to weld 1.2 mm-thick X2CrTiNb18 ferritic stainless steel (FSS) in the form of square butt joint. The microstructure and mechanical properties of two types of joints were characterized and compared. The results showed that beam oscillation had a marginal effect on the unidirectional tension properties of the joints. However, the plasticity and fracture toughness of the joint were markedly increased. The beam oscillation changed the morphology and microstructure of the weld. It transformed the outer profile of the weld cross-section into an inverted trapezoid, and formed an equiaxed grain zone in the weld. Beam oscillation decreased the angle between the growth direction of columnar crystals around the equiaxed grains and the weld centerline, which improved the deformation coordination of the grains. The plasticity and fracture toughness of X2CrTiNb18-FSS joints were also improved accordingly.

Effect of beam oscillation on the fluid flow during laser welding

In the present study, a finite element based numerical model is developed to evaluate heat transfer and fluid flow during the laser welding process with a moving heat source. The developed model solves the fully coupled equations of incompressible fluid flow and heat transfer. In this study, laser beam welding involving non-oscillating to oscillating beam is compared with both conditions under similar heat input per unit length i.e., same power and welding speed. Dimensionless coefficients for mass and heat transport were used to analyse the effects of Marangoni flow and thermal buoyancy. Varying combinations of radius and frequency of oscillations are studied at a constant circumferential velocity.

The effect of beam oscillation on laser welding of AA2219-T87 under subatmospheric pressure

Aluminum alloy AA2219 is widely used in the aerospace industry due to its high specific strength, and corrosion resistance, especially for the production of propellant tanks of space rockets. With the rapid development of laser sources, the welding of metal materials changes gradually from arc welding to laser welding, but pore defect drags the application of laser welding of aluminum alloy. To solve this bottleneck problem, this paper investigates the effect of laser beam oscillation on welding of AA2219 under subatmospheric pressure (LOWSP). The experimental results showed that LOWSP has significantly improved the surface morphology, penetration depth, microstructure,and mechanical properties of the weld seam. The EBSD testing analysis shows that the low-angle grain boundaries (LAGBs) take up the largest proportion in the microstructure with the increased proportion of equiaxed grains, and the grain size is further refined in LOWSP. When welded at the optimal laser beam oscillation frequency of 80 Hz under the pressure of 102 Pa, the pore was almost inhibited and the tensile strength of the weld seam reached 388.62 MPa, up to 83.16% of the base metal (the current level of the industry is generally between 300 ∼ 360 MPa). It is believed that the reduced boiling point of the aluminum alloy under subatmospheric pressure accelerated the molten metal flow rate, the stirring effect of laser beam oscillation on weld microstructure within molten pool significantly eliminate porosity, therefore the LOWSP process generated the refined grain size and the improved mechanical properties of the weld seam.

Effect of Beam Oscillation on Metallurgical and Mechanical Properties of the Electron Beam Welded SS 316 Welded Joints

Effect of Beam Oscillation on Metallurgical and Mechanical Properties of the Electron Beam Welded SS 316 Welded Joints

Effect of Beam Oscillation on Creep Properties of Electron Beam Welded AISI 316L Stainless Steel

Effect of Beam Oscillation on Creep Properties of Electron Beam Welded AISI 316L Stainless Steel

Effect of beam oscillation on intermetallic compounds and mechanical properties of steel/aluminum laser welded joint

Brittle Fe-Al compounds limit the performance of the steel/aluminum joint. Beam oscillation laser technology was performed to control the thickness, morphology and distribution of intermetallic compounds (IMCs) at interface. The results showed that beam oscillation significantly reduced the thickness of IMC layer. When oscillation frequency was 10 Hz, the needle-like phase embedded in aluminum matrix was obviously passivated in the circular oscillation mode, while the needle-like phase at interface tend to distribute parallel to the layer-like IMC, and formed a “bite” connection effect with aluminum matrix. In the linear oscillation mode, the needle-like phase disappeared, and smooth and flat interface was obtained. Compared with the non-oscillation mode, in the case of circular or linear oscillation mode, the width of molten pool was significantly increased, the crystal grains were refined, and the joint property was increased by 26% and 17% respectively, which were caused by the combined effect of mechanical bonding and metallurgical regulation. The influence mechanism of beam oscillation on the thickness, morphology and distribution of IMC at interface was revealed by high-speed photography and finite element simulation, which provides a new idea for the welding of steel/aluminum dissimilar materials.

Effect of Beam Oscillation on Residual Stress and Corrosion Properties of AISI 316L Electron Beam Welds

Effect of Beam Oscillation on Residual Stress and Corrosion Properties of AISI 316L Electron Beam Welds

Role of beam oscillation on electron beam welded zircaloy-4 butt joints

Effect of beam oscillation on microstructure, mechanical properties and corrosion behaviour of electron beam butt weld of zircaloy-4 was investigated. Joints made with beam oscillation demonstrated higher ductility, toughness and notch tensile strength and higher corrosion resistance than the joints prepared without beam oscillation. Heat mixing and faster cooling associated with beam oscillation restrict unidirectional crystal growth favouring the development of a more uniform, fine basketweave widmanstätten structure in the fusion zone. Improvement in mechanical and corrosion properties using beam oscillation was attributed to the development of a more uniform microstructure, lesser segregation and lesser intermetallic precipitation in the fusion zone.

Study of porosity suppression in oscillating laser-MIG hybrid welding of AA6082 aluminum alloy

The AA6082 aluminum alloy was welded by oscillating laser-MIG hybrid welding. By using beam oscillation, the porosity can be effectively suppressed in the range of 100−300 A arc current, especially at low arc current level. Percent porosity decreased greatly with the increase of the oscillating amplitude and frequency. The threshold frequency of porosity-free at different amplitudes were achieved. The effect of beam oscillation on porosity formation and suppression was studied by observing keyhole behavior via a “sandwich” high-speed video method. It was found that the porosity suppression depended on three reasons. Firstly, high-frequency oscillating keyhole can “capture” the bubbles or cavities in the molten pool and solidification front. Secondly, high-frequency oscillating keyhole can enlarge the diameter of keyhole and improve keyhole stability. Thirdly, beam oscillation can form stirring effect in molten pool, which can produce turbulence to reduce possibility of bubbles moving to the solidification front.

Effect of beam oscillation on microstructure and properties of laser-TIG hybrid welding of D406A ultra-high strength steel

30Si2MnCrMoVE (referred to as D406A) has not only ultra-high strength but also good toughness, which is the most critical material for solid rocket engine shell. But current methods are low efficient and poor welding quality. In this paper, a laser-TIG hybrid welding with beam oscillation was employed to join 2 mm-thick D406A steel in butt joint. Two beam oscillation modes that are continuous and pulse circular were investigated. It was found that the beam oscillation refined the dendrite structure and was beneficial to the formation of equiaxed grains in the fusion zone, and turned the columnar grains into different orientations and homogenized structures. The continuous circular oscillation had the best stirring effect on the molten pool, and the weld had the finest grain and the most amount of equiaxed grains. As a result, the transverse residual stress obtained using continuous circular oscillating of the weld was the lowest (422 MPa) and the most uniform, 40.6 % lower than the weld without oscillating. Besides, the beam oscillation had little effect on the tensile strength of the weld, but improved the ductility obviously. The strain with continuous circular oscillation was up to 5.9 %, 18 % higher than that of the pure TIG weld.

Texture mapping in electron beam welded dissimilar copper-stainless steel joints by neutron diffraction

In this study, the crystallographic texture variation of electron beam welded dissimilar copper to 304L stainless-steel joints was investigated using Time-of-flight neutron diffraction measurements. The effect of beam oscillation by changing its oscillation diameter on texture orientation variation was evaluated. Neutron diffraction measurements were performed using General Materials Diffractometer beamline at Rutherford Appleton Laboratory neutron radiation source. Phase fractions and variations of crystallographic texture in terms of pole figures and inverse pole figures were obtained. The stronger texture we found in all regions of the joints i.e. heat-affected zone and fusion zone for oscillating beam compared to its non-oscillating counterparts. Also, by increasing the oscillation diameter, from its optimum value, a weaker texture was found, which had a detrimental effect on mechanical properties. Electron-backscatter diffraction texture measurements were also performed to compare and complement the results obtained from neutron texture.

Effect of beam oscillation on porosity and intermetallics of electron beam welded DP600-steel to Al 5754-alloy

Formation of porosity and intermetallic compounds (IMCs) were studied in electron beam welded (EBW) DP-600 steel to Al-5754 alloy joints at three different weld conditions such as without beam oscillation, with beam oscillation and with varying beam oscillation diameter. X-ray Diffraction (XRD), scanning electron microscopy (SEM), microhardness, three-dimensional X-ray computed tomography (XCT) were used to characterize porosity and IMCs distribution in these weld joints. Beam oscillation with optimum oscillation diameter (1 mm diameter) improved the weld quality by reducing the amount, maximum size and porosity contents in weld zone significantly. For IMCs, average size increased little bit but maximum size, percentage of formation and amount reduced. By increasing oscillation diameter (2 mm diameter) beyond optimum value (1 mm diameter), quality of joints was found to deteriorate with accompanying higher porosity content, average pore size, average IMCs size etc. Raman spectroscopy and gas analyzer were also used to identify and quantify the entrapped gases in the weld joint.

Influence of beam oscillation in electron beam welding of Ti-6AL-4V

Effect of beam oscillation on the evolution of microstructure and its correlation to mechanical properties for butt-welded Ti-6Al-4V plates has been studied using electron beam welding. Joints made with oscillating beam demonstrated higher ductility (by 10 to 15%) and notch toughness (by 20 to 30%) compared to those produced by non-oscillating beam. Evolution of such improved mechanical properties with beam oscillation has been corroborated with more uniform and fine microstructure, which has been attributed to the intense heat mixing, reduced temperature gradient, and more uniform cooling in the weld track. Narrow heat-affected zone and fusion zone with considerably reduced undercut depth were also obtained for oscillating beam joints. Interestingly, residual stress was found to be more in welds prepared with beam oscillation than its non-oscillating counterparts, although the magnitude of such stress irrespective of the welding condition was found to be much lower than those reported for arc welding.