CO2 Laser Beam Welding Research Articles

Elevated temperature rusting characteristics of UNS 31254 weldments within the operational confines of fossil fuel-fired plants and municipal waste incinerator surroundings at 700 °C

ABSTRACT This study investigates the air oxidation and rusting traits of fully austenitic alloy 254 stainless steel samples at 700°C after pulse current gas tungsten arc welding (PCGTA) and CO2 laser beam welding (CO2 LBW), with or without molten salt, relevant to coal-fired plants and waste incinerator settings. Among the weldments studied, CO2 laser weldments demonstrate greater resilience to corrosive gas and salt amalgamation, as well as air oxidation, compared to gas tungsten arc weldments, possibly due to thermal disparities and microstructural differences inherent in the welding processes. Protective oxides enhance corrosion resistance in air-oxidised samples, while corrosive compounds like CrS, Cr2K2O7, etc., reduce corrosion resistance and promote spallation in salt-degraded material. A thermogravimetric approach was used to assess rusting effects, alongside microstructural analysis employing optical, Scanning electron microscopy/ Energy dispersive x-ray spectroscopy (SEM/EDS), and X-Ray diffraction analysis (XRD) techniques.

Mechanical properties of CO2 laser beam butt-welded plates of Hastelloy c-276

In the current investigation, thermo-mechanical analysis is carried out for Hastelloy C-276 using laser beam welded butt joints. The Gaussian heat source model is used for transient thermal analysis, and the maximum temperature at the weld area resulted in residual stresses within safe limits. To validate, the experimentation was carried out with CO2 Laser beam welding using an L4 orthogonal array. Sample 2 had the least-residual stresses in the weldment, and the mechanical and metallurgical properties studies were carried out. The residual stress distribution was measured using X-ray diffraction and was acceptable within the yield limits of the material. Finite Element Analysis (FEA) and experimental residual stresses were compared; the FOS was 2.088, and the remaining samples were more than 2.0 compared to the base material tensile strength. Tensile tests confirmed that the strength of the weld zone is higher than that of the parent metals.

Optimizing CO2 laser beam welding parameters for magnesium hybrid metal matrix composites (ZE41A)

ABSTRACT The current work is the investigation of optimizing input welding parameters of CO2 laser welding of two stir squeeze casted magnesium (ZE41A) matrix silicon nitride and alumina-reinforced hybrid metal matrix composites (MMCs). Two similar hybrid MMC plates were joined by the CO2 laser beam welding process and were investigated for input welding parameters influencing the metallurgical and mechanical properties. The identified parameters were subjected to optimization by Box-Behnken experimental design of Response Surface Methodology (RSM) and the experimental trials were validated by Analysis of Variance (ANOVA). With increases of 16% and 23%, the microhardness and tensile strength peaked at 207 MPa and 78 HV, respectively. The ideal input welding settings were 3500W of laser power, 4 mm/minute welding speed, and a focus length of 1.5 mm.

Evaluation of residual stresses in CO2 laser beam welding of SS316L weldments using FEA

Laser welding is used in critical component production when tight tolerances like minimal distortions and residual stresses are required. Laser beam welding offers a lower heat input, a smaller heat affected zone, lower residual stresses, minimum distortions, and greater mechanical joint characteristics than conventional welding does. In order to simulate the laser welding process used on SS316L plates, the Gaussian heat source model was used. The model is developed and simulated with volumetric heat source model with APDL coding using ANSYS. The thermal profiles at the joint cross sections via welded area, interface across joints is taken for the analysis. The maximum temperature was observed at the fusion zone and associated zones. The residual stresses are analysed in the same path and found the stresses are in safe limits of base material. Predicted and experimentally measured residual stresses are close agreement with 10%.

Distortion control in CO2 Laser Beam dissimilar welds of SS316L to INCONEL625 plates

The paper attempts to join similar and dissimilar joints by employing CO2 laser beam welding. The SS316L and INCONEL625 plates of 5mm thick plates are used. The L4 orthogonal array was chosen for the experimentation. Three parameters are chosen in two levels, and four trials are optimized. Analysis of Variance (ANOVA) is used to optimize and determine the most critical parameters. The weldments have undergone visual, X-ray radiography, and macrostructure examination to verify the quality of the weldments verified with full penetration. Distortion in dissimilar weldments may be measured using a vernier height gauge. Simple inspection methods, No-way ANOVA, Linear Figures, and ANOVA were used, and two parameters were identified with 99% criticality. ANOVA shows 95% significance for distortion with welding speed at 51.9%, welding current at 13%, and shielding Flow rate at 12.3% contribution. The welding speed and laser power are significant, while shielding gas is not a critical parameter but essential for the quality of the joint.

Hot corrosion and air oxidation behavior of pulsed current gas tungsten arc welded and CO2 laser beam welded SMO 254 at 800 °C

This research aims to investigate the hot corrosion behaviour of SMO 254 steel samples after PCGTA and CO2 laser beam welding, as well as air oxidation. A salt mixture simulated the waste incinerator environment involving 40 wt. % Na2SO4 + 40 wt. % K2SO4 + 10 wt. % NaCl + 10 wt. % KCl are employed. The hot corrosion tests were carried out for 103.33 h at 800 °C, with a thermogravimetric investigation availed to calculate the impact of corrosion. The weight gain rate for PCGTAW molten salt corroded specimens is greater (33.45 mg/cm2) than the weight gain rate for CO2 Laser molten salt corroded specimens, which is 67.55% higher. The weight of the hot corroded sample rises in the molten salt surroundings due to the creation of compounds including CrS, FeMo2S4, Na2S, Fe2O3, K2S3, Cl4CrNa2. CO2 LBW air oxidation has the lowest rate of corrosion due to the synthesis of beneficial oxides, such as NiCr2O4, NiO, and Cr2O3. Optical microscopy and SEM/EDS were employed on both surface and cross-sectional surfaces to get microstructure at the interface of the fusion region, parent metal, and fusion region using point mapping, line mapping, and X-ray mapping techniques. The corrosion products produced during corrosion were studied using XRD.

Mechanical and Metallurgical Characterisation of CO2 Laser Beam Welding AISI 4130 and AISI 310 Sheets of Steel

Abstract Laser Beam Welding (LBW) is the fusion welding technique in which coalescence is produced by heating the work piece by impingement of concentrated beam of laser light. In this paper a full depth butt welding of alloy steel AISI 4130 and stainless steel AISI 310 of 2 mm thickness by using CO2 Laser Beam Welding machine has been performed. Design of experiment is done by using Taguchi method L25 i.e. level 5 by considering process parameters i.e. power, welding speed, beam angle, focal point position and focal length. The experimental output results that are measured for the mechanical properties of welds (Ultimate Tensile Strength and Hardness). The analysis was carried out to explain the influence of the LBW processing parameters values on the mechanical and microstructural aspects. The weld Joint is analysed by Optical Microstructure and Scanning Electron Microscopy (SEM). The Energy Dispersive X-Ray Analysis (EDAX) was carried out to determinate the chemical composition of the weld zone.

Mechanical and Metallurgical Properties of CO2 Laser Beam INCONEL 625 Welded Joints

In the frame of the circular economy, welding of Ni-based superalloys has gained increasing importance when applied, for instance, to repairing highly expensive components widely used in strategical sectors, such as the defense and aerospace industries. However, correct process parameters avoiding metallurgical defects and premature failures need to be known. To reach this goal, Inconel 625 butt-welded joints were produced by CO2 laser beam welding and different combinations of process parameters. The experimental investigation was carried out with three parameters in two levels with an L4 orthogonal array. Laser power, welding speed, and shielding gas flow rate were varied, and the results were reported in terms of mechanical properties, such as microhardness, tensile strength, distortion, residual stress, and weld bead geometry, and metallurgy. At a lower welding speed of 1 m/min, the full penetration was observed for 3.0 kW and 3.3 kW laser powers. However, sound welds (porosity-free) were produced with a laser power of 3.3 kW. Overall, the obtained full-penetration specimens showed a tensile strength comparable with that of the parent material with residual stresses and distortions increasing with the increase in heat input.

Distortion Control for Dissimilar Welding of SS321 to Hastelloy C-276 with CO2 Laser Beam Butt Joints Using Taguchi Methods

The laser beam welding process is a promising technology because of its reliability and ability to automate the process easily. This study aims to analyze distortion for dissimilar laser weld joints. Hastelloy C276 and SS321 plates are joined by using the CO2 Laser beam welding. Welding current, welding speed and shielding gas flow are chosen as process parameters for preparing butt joints. Each of the factors has two levels to control the parameters of the output. Experimentation was conducted with four trails by using an L4 orthogonal array. The quality of the welds and bead geometry are verified through macrostructure examination. The Vernier height gauge was used for the measurement of distortion in the weldments. Lower the better-quality characteristic is chosen for the response. ANOVA studies identified laser power at 81%, the weld speed at 16% parameters is a contribution with a statistical of about 95%. Full penetration was observed for all the experimental trails.

Mechanical properties and fatigue behavior of CO2 laser beam welded armor steel joints

Abstract Armor 500T steel used in armored military vehicles and marine vehicles were joined by CO2 laser beam welding method by applying three welding powers and two welding speeds under shielding argon atmosphere. From microstructure and microhardness results, under low laser welding power and high welding traveling speeds, microstructural transformation in the joining region of the performed welds occurred at a narrower distance as compared to other parameters, and it was determined that four regions formed independent of each other for each parameter group. Furthermore, it was determined that there is a gradual decrease in the microharness values of samples in which welding parameters cause heat input to decrease. The fatigue test results of all samples showed high strength properties in the parameters with high heat input. Additionally, tensile test results for all samples with high heat input parameters also exhibited high strength properties. Fracture at the intersection at high heat input parameters of a relatively ductile separation type occurred in HAZ whereas, at other parameters fracture occurred at the weld center and wide gap semi-brittle fracture behavior was observed. As a consequence, it was found that the most effective parameter as compared with laser welding power is laser welding traveling speed.

An Analysis of the Mechanical and Metallurgical Behavior of AISI 4130 Steel After Co2 Laser Beam Welding Process

Alloy metal has received special attention in the aerospace and defense areas. The AISI 4130 alloy steel had been also considered, since it is applied in landing gears, small aircrafts engine cradles, and besides general industries. The Laser Beam Welding of high strength metals obtained small Weld Zone and better quality with good appearance. In this research work, a Laser Beam Welding (LBW) is used to weld AISI 4130. The experiments are conducted accordingly combination of Taguchi L25 based 5 levels of Laser Power, Speed, Angle, Focal Length and Focal Point Position. The AISI 4130 weld joint Bead Width and tensile strength are measured and analysed by ANOVA. Microstructure and SEM with EDAX are using to analysis the AISI 4130 weld joint.

Numerical investigation on welding process parameters optimisation using multi-objective optimisation technique

This study considers one such successful application of multi objective optimisation technique on CO2 laser beam welding process parameters with cupronickel as a material. Though several process parameters exist within the literature, only most cited parameters are considered namely focal position, welding speed, welding current and welding angle. In initial phase the experimental procedure was conducted with CO2 laser beam welding, further the obtained outputs given as inputs to the numerical evaluation. The technique for order of preference by similarity to ideal solution (TOPSIS) has been considered as solution methodology for this study to identify the optimised process parameters. Several mechanical properties are considered as the multi-objective functions for this study which includes impact, elongation, hardens, tensile strength and yield strength. With the assistance of this multi objective optimisation, the researchers, shed light on one of the new applications of welding technologies.

Numerical investigation on welding process parameters optimisation using multi-objective optimisation technique

This study considers one such successful application of multi objective optimisation technique on CO2 laser beam welding process parameters with cupronickel as a material. Though several process parameters exist within the literature, only most cited parameters are considered namely focal position, welding speed, welding current and welding angle. In initial phase the experimental procedure was conducted with CO2 laser beam welding, further the obtained outputs given as inputs to the numerical evaluation. The technique for order of preference by similarity to ideal solution (TOPSIS) has been considered as solution methodology for this study to identify the optimised process parameters. Several mechanical properties are considered as the multi-objective functions for this study which includes impact, elongation, hardens, tensile strength and yield strength. With the assistance of this multi objective optimisation, the researchers, shed light on one of the new applications of welding technologies.

Investigations on induced residual stresses, mechanical and metallurgical properties of CO2 laser beam and pulse current gas tungsten arc welded SMO 254

This research article focuses on the joining of SMO 254 stainless steel by autogenous CO2 Laser beam welding and pulsed current gas tungsten arc welding (PCGTAW) with ERNiCrMo3 filler. The studies proved that full penetration could be achieved on the weld joint of a 5 mm thick plate with a reduced heat input of 120 J/mm in the laser welding while in the case of PCGTAW it was 3032 J/mm. An attempt is made to do a comparative evaluation of the microstructure changes which have occurred owing to welding and thereby the mechanical properties. The studies revealed the lack of deleterious phases in both welding techniques. Presence of grain boundary thickening near the fusion zone and elemental segregation was observed in PCGTAW joints. The residual stress measurements by X-ray diffraction method were executed over the cross-section of the two different weldments. An attempt is made to represent the stresses variation along the weld region, heat affected zone and the base metal graphically. The tensile test validated that in every case the rupture ensued at the base metal and the higher weldment hardness than base metal proves the soundness of the joint.

Welding characteristics of butt-welded Inconel625 plate using CO2 laser beam

Abstract Inconel weldments are widely used in automobile and structural industries. In this study, the joints of Inconel625 are made with CO2 Laser beam welding process. The experimentation is carried out with two sets of process parameters varying the laser power and estimating the response of the welded component. Radiography analysis and distortion in the weldments are carried out. Distortion is measured using the Vernier height gauge. The lower the better-quality characteristics are chosen for distortion. The welds are free from flaws and the lower heat input results in the lower distortion.

Interactions Between Fibroblast Cells and Laser Beam Welded AISI 2205 Duplex Stainless Steel

Because of their high mechanical strength, excellent corrosion resistance and good weldability, duplex stainless steels are mostly used in industries such as oil, chemistry, petrochemistry, food and occasionally used in medical industry. These properties have enabled us to use duplex stainless steels in biomedical applications recently. Accordingly, duplex stainless steel material can be highly important to examine the toxic effect on the cells. In this study, the effect of the AISI 2205 duplex stainless steels which are joined by CO2 laser beam welding on viability of L929 fibroblast cells has been studied in vitro for the first time. For this aim, the cells were kept in DMEM/F-12 (Thermofisher Scientific 31331-028) medium for 7 days. The viability study was experimentally studied using the MTT (Thiazolyl Blue Tetrazolium Bromide) method for 7 days. The cell viability of the laser beam welded sample has been detected to be higher than that of the base metal and the control based on 7th day data. According to the obtained results, it was revealed that laser beam welded and base metal AISI 2205 duplex stainless steel has been found suitable to study for biomedical applications. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.18006

Optimization of CO2 Laser Beam Welding Process Parameters to Attain Maximum Weld Strength in Dissimilar Metals

In this study, influence of CO2 laser beam welding (LBW) process parameters such as laser power (P), welding speed (S), focal distance (F) on dissimilar metals of low carbon steel (AISI 1018) and austenitic stainless steel (AISI 316) was examined by using central composite design (CCD) based response surface methodology (RSM). Experimental investigations were performed on 4 kW CO2 laser (TRUMPF TLC1005) with the laser beam spot diameter of 0.15mm and a focal length of 15-25mm. Analysis of variance (ANOVA) was used to analyze the interaction effect of different parameters on the maximum weld strength. A ratification experiment was also carried out in order to validate the optimal process parameters values. Based on the investigation, the maximum weld strength of 458.21 N/mm2 was observed for dissimilar metal butt joint with the optimized laser power of 2600W, the focal distance of 25 mm and a welding speed of 1.5 m/min. Microstructure studies revealed cellular austenite in the form of dendrite and columnar type features accredited to the higher cooling rates concerned with laser welding process. Energy dispersive X-ray analysis (EDX) is carried out to measure the nature of the chemical element distribution in the weld interface. Microhardness tests showed that the maximum hardness was produced in weldment 151-458 Hv and fusion boundary of austenitic stainless steel 193-434 Hv, fusion boundary of low carbon steel 156-468 Hv.

Investigations on metallurgical and mechanical properties of CO2 laser beam welded Alloy 825

ABSTRACTIn the research work, an attempt is made to join nickel-based alloy 825 by employing CO2 laser beam welding. Successful full penetration weld joint of a 5 mm thick plate is achieved with a very low heat input of 120 J-mm−1. Narrow weld bead width of 0.6 mm at the root and 1.6 mm at the cap is observed fusion zone; the interface and base metal microstructures have been examined using both optical and scanning electron microscopic techniques to understand the microstructural changes which have occurred due to laser welding. A range of tests of Vickers micro hardness, tensile and impact tests had been performed on the weldment to ascertain the mechanical properties of the joint. Tensile failure at the base metal and a 180° root bend test conducted on the weldment ascertain the soundness of the weld joint produced. An attempt is made to correlate the microstructure and mechanical properties of the weldment. Intermetallics TiN and Al4C3 observed in the SEM\\EDS analysis at the fusion zone are found to have improved the weld metal strength and hardness.

An experimental study on CO<SUB align="right">2 laser beam welding of AISI 304SS and Cu dissimilar pipes

Effect of process parameters such as laser power and welding speed on CO2 laser beam welding (LBW) of commercially pure copper (Cu) pipes with AISI 304 stainless steel (SS) pipes is investigated in the present study. Laser power is varied from 1.5 to 3.5 kW; heat source velocity/scan speed is varied from 0.72 to 4.5 m/min; and beam diameter is maintained at 0.18 mm operating in Gaussian mode. The microstructural developments and mechanical properties of the welded samples are investigated. It is observed that acceptable microhardness values, across the weld pool and along the depth direction have been obtained, and those are found to be related to the temporal continuation and quenching of plasma. The mechanical properties in terms of tensile stress realised values up to 286.232 MPa and the fracture was observed to be outside the weld zone. The growth of keyhole phenomena has been simulated and compared with experiment.

An experimental study on CO<SUB align="right">2 laser beam welding of AISI 304SS and Cu dissimilar pipes

Effect of process parameters such as laser power and welding speed on CO2 laser beam welding (LBW) of commercially pure copper (Cu) pipes with AISI 304 stainless steel (SS) pipes is investigated in the present study. Laser power is varied from 1.5 to 3.5 kW; heat source velocity/scan speed is varied from 0.72 to 4.5 m/min; and beam diameter is maintained at 0.18 mm operating in Gaussian mode. The microstructural developments and mechanical properties of the welded samples are investigated. It is observed that acceptable microhardness values, across the weld pool and along the depth direction have been obtained, and those are found to be related to the temporal continuation and quenching of plasma. The mechanical properties in terms of tensile stress realised values up to 286.232 MPa and the fracture was observed to be outside the weld zone. The growth of keyhole phenomena has been simulated and compared with experiment.