Effect of laser beam oscillation parameters on weld geometry and mechanical properties of dissimilar dual-phase steel welds

Parametric investigation of femtosecond laser welding on alumina using Taguchi technique

Laser beam welding is one of the most favorable welding technique and its importance in industry is demanding due to higher welding speeds and lower dimensions and distortions in the welds. Moreover, its high strength to weld geometries and minimal heat affected zones makes favorable for various industrial applications. In the present study, laser welding of titanium alloy was investigated to observe the effects of parameters on the bead geometry and metallurgical properties. The laser power and welding speeds were varied to identify their impact on the formation of weld geometry. The width and depth of the fusion zone is varied with welding conditions. The finer grains identified in weld zone and the width of heat affected zone was significantly changes with laser welding power. The mechanical properties of the weld joint are controlled by obtaining optimum weld bead geometry and width of the head affected zone in the welds.

This paper presents an experimental study of influence of shielding gas composition on TIG produced weld bead geometry and its corrosion resistance. Short overview of properties, application and weldability of Titanium was provided in the introduction of the paper. Within the framework of the experimental work, four bead on plate welds were produced using two different shielding gases (EN ISO 14175: I1 and EN ISO 14175: I3) and two welding speeds (v1 = 9 cm/min, v2 = 15 cm/min). Influence of shielding gases was investigated by analysing weld bead geometry and corrosion resistance testing. Weld bead geometry analysis showed that shielding gas has a significant influence on the penetration and width. Using EN ISO 14175: I3 as shielding gas resulted in larger penetration and width of the weld bead when welding with both welding speeds. Corrosion testing implicates that higher heat input results in a lower corrosion resistance of the welded joint.

The orthogonal experimental designing method and regression are used to analyze the effect of welding process parameters on weld shape quality in twin-arc high-speed submerged arc welding (SAW). The numerical simulation experiments are done by the orthogonal experimental designing method. The process parameters of the welding current, voltage, speed and distance of welding wires are selected as studying factors, and the welding width, penetration and reinforcement are the weld shape quality indexes. The effect relation of each welding process parameter on the welding width, penetration and reinforcement are studied, and the effect degree of weld shape indexes by the welding current, voltage, speed and distance of welding wires are identified. It obtain by analysis results of experiment that the welding current, voltage and speed have a greater effecting on weld shape quality and determined the arc linear energy, which are easy to be adjusted and controlled. The quality of weld shape and welding speed can be further improved by the reasonable selection and optimization of the welding process parameters.

Laser beam welding of dissimilar stainless steels in a fillet joint configuration

While gas metal arc welding of aluminum has been widely implemented in automotive industry, it is prone to process disturbances. Therefore, an effective monitoring method is necessary to ensure the weld quality (e.g., weld bead height, width and penetration). In this study, an online method was developed to estimate the weld bead geometry using the combination of the real time welding signals, characteristics of weld bead geometry and a liquid surface model. The liquid surface model can represent the steady-state geometry of the weld pool with varying characteristics, such as volume, boundary conditions and surface tension. To model the geometry of the weld pool, the weld pool moved and updated its geometry in response to the merging of each new droplet. The detachment time and size of the new droplet were obtained by analyzing real time welding voltage and current. The surface tension was characterized by the effective contact angle measured under various welding conditions. Moreover, the effective contact angles and radius of arc-affected zone were introduced to significantly simplify the complicated thermal behavior during welding. Finally, the weld bead geometry was estimated using real welding signals in both globular and spray transfer modes and validated with the experimental results. This method predicts weld bead geometry with satisfied accurancy for engineering use and in a comparable speed as the welding speed; and thus can be applied as an online monitoring method for the weld bead quality.

To study the influence of process parameters on weld bead geometry in shielded metal arc welding

Effect of incident angle on weld microstructure and mechanical properties of laser beam welded nitronic −50 austenitic stainless steel joints

Effect Of Welding Speed On Weld Bead Geometry And Percentage Dilution In Gas Metal Arc Welding Of SS409L

A 2kW Ytterbium fiber laser, YLR-2000, was used for welding of 780MPa grade high strength steel. In the present work, this high strength steel is a kind of heat rolled, fine microstructure low carbon high strength steel used for welded constructions. The effects of defocusing distance, welding speed, shielding gas and its flow rate on cross section bead shape and penetration were studied in continue wave laser beam welding. The effects of frequency and duty cycle on the cross section bead shape and penetration were also studied in pulse fiber laser beam welding. In the fiber laser welding, square wave and triangle wave power output were adopted. The results showed that the pulse frequency and duty cycle of laser power had affected the bead shape and penetration in square wave Fiber laser welding. The pulse frequency of laser power had not effect on the bead width and penetration in triangle wave fiber laser welding. The microstructures of weld metals in different heat input were observed by optical microscopy. The hardness of welds was also tested and compared among welds welded at different welding speeds, in other words, in different heat inputs.

Laser wobble welding of fluid-based cooling channel joining for battery thermal management

Microstructure and mechanical properties of weld metal in laser and gas metal arc hybrid welding of 440-MPa-grade high-strength steel

Laser beam welding of copper (Cu) using near-infrared radiation is extremely challenging due to its high thermal conductivity and large laser reflectivity. In the present study, the challenges and benefits of using spatial beam oscillation during quasi-continuous wave (QCW) pulsed laser beam welding of 0.4 mm Cu to 1 mm Cu in lap joint configuration are presented. This work demonstrates how laser beam oscillating parameters can be used to control the laser weld quality and laser weld dimensions for Cu-Cu joining. Compared to a non-oscillated laser beam, welds made using laser beam oscillation showed fewer spatters, porosities, and better surface quality. Four levels of oscillating amplitudes (0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm) and oscillating frequencies (100 Hz, 200 Hz, 300 Hz, and 400 Hz) were compared to reveal the effect of beam oscillation parameters. The weld width was mainly controlled by oscillating amplitude, while weld penetration was affected by both oscillating amplitude and frequency. As the oscillating amplitude increased, the weld width increased while the weld penetration decreased. Increasing the oscillating frequency reduced the weld penetration but had a negligible effect on the weld width. The maximum tensile force of approximately 1944 N was achieved for the joint with a high width-to-depth ratio with an oscillating amplitude of 0.8 mm and an oscillating frequency of 200 Hz.

The development of thermomechanically controlled processed (TMCP) high-strength steel (HSS) has significantly contributed to designing and developing the intricate structural components. It has broader applications in the cranes and lifting process industry (base frame, crane jibs, and crane columns), trailers, agricultural and forestry machinery, earth-moving equipment, etc. However, the development of new-grade steels with higher tensile strength led to higher requirements for welded joints, and the associated weldability issues have inspired detailed studies on electron beam welding (EBW) with different beam oscillations. Beam oscillation application with EBW processes improves the welding efficiency, weld quality, weld geometry, keyhole, etc., affecting the welded joints mechanical and microstructural properties. Thus, the present study investigates the impact and comparison of various beam oscillations on the microstructural and mechanical properties of EB-welded S1100M steel. The influence of welding parameters on the microstructure of welded joints was analyzed using a scanning electron microscope (SEM) and electron backscattered diffraction (EBSD). The analysis focused on evaluation of grain sizes, morphologies, distributions, and crystallographic orientations of different phase constituents in fusion zone (FZ) and heat-affected zone (HAZ). The mechanical properties were analyzed using hardness, tensile, and Charpy V-notch impact tests. The texture in the FZ is typically random, while the HAZ typically exhibits a strong rolling texture. In general, the cooling rate in EBW is very fast, possibly resulting in a fine-grained structure and reduced formation of coarse second-phase particles in the weld zone. The elliptical beam oscillation showed the highest hardness in HAZ 450 HV10. Elliptical beam oscillation slightly improves the welded joint’s tensile strength, and the impact test showed mixed fracture behavior.

Welding polarity has influence on welding stability to some extent, but the specific relationship between welding polarity and weld quality has not been found, especially under the hyperbaric environment. Based on a hyperbaric dry welding experiment system, gas metal arc welding(GMAW) experiments with direct current electrode positive(DCEP) and direct current electrode negative(DCEN) operations are carried out under the ambient pressures of 0.1 MPa, 0.4 MPa, 0.7 MPa and 1.0 MPa to find the influence rule of different welding polarities on welding spatters and weld bead geometry. The effects of welding polarities on the weld bead geometry such as the reinforcement, the weld width and the penetration are discussed. The experimental results show that the welding spatters gradually grow in quantity and size for GMAW with DCEP, while GMAW with DCEN can produce fewer spatters comparatively with the increase of the ambient pressure. Compared with DCEP, the welding current and arc voltage waveforms for DCEN is more stable and the distribution of welding current probability density for DCEN is more concentrated under the hyperbaric environment. When the ambient pressure is increased from 0.1 MPa to 1.0 MPa, the effects of welding polarities on the reinforcement, the weld width and the penetration are as follows: an increase of 0.8 mm for the weld reinforcement is produced by GMAW with DCEN and 1.3 mm by GMAW with DCEP, a decrease of 7.2 mm for the weld width is produced by DCEN and 6.1 mm by DCEP; and an increase of 3.9 mm for the penetration is produced by DCEN and 1.9 mm by DCEP. The proposed research indicates that the desirable stability in the welding procedure can be achieved by GMAW with DCEN operation under the hyperbaric environment.