Welding Cladding Process Research Articles

Modelling the weld cladding process to predict weld clad position and shape error

Wire arc additive manufacturing (WAAM) is one of the most productive metal additive manufacturing methods. One of its most promising applications holds in the manufacturing of difficult-to-cut materials where production costs can be reduced with minimizing the time of machining and total tool costs. To develop a correct WAAM, technological processes for manufacturing complex-shaped components welding torch path corrections and welding power corrections have to be made especially in critical sections such as corners and sharp edges. A predictive mathematical model of the material cladding during the WAAM process has been developed for the purposes of generating an optimal toolpath of the WAAM clads. This predictive mathematical model is simplified to reflect the important physical phenomena in the weld pool but also to optimize computing time. In this paper, the principle of the mathematical model is described, and its functionality is verified by the welding experiments with five different welding power settings. For the initial calibration of the model parameters single straight-line weld clads with 5 different welding power settings (wire feeds) ranging from 5.0 to 8.6 m/min were investigated. 3D scans of these welded samples are used for the verification. With the calibrated simulation model, it was possible to predict the precise shape with a maximum deviation circa 0.20 mm. The start portions of the weld clads seem more complex having the deviation circa 0.30 mm. These are valuable results as the WAAM technology is generally considered to be reasonably rough.

Reinforcement of Tooling Using Residual Stresses Generated by Cladding by Arc Welding

Cladding is typically used to protect components from wear and corrosion while also improving the aesthetic value and reliability of the substrate. The cladding process induces significant residual stresses due to the temperature difference between the substrate and the clad layer. However, these residual stresses could be effectively utilized by modifying processes and geometrical parameters. This paper introduces a novel methodology for using the weld-cladding process as a cost-effective alternative to various existing reinforcement techniques. The numerical analyses are performed to maximize the reinforcement of a cylindrical tool. The investigation of how the weld cladding develops compressive stresses on the specimen in response to a change in the weld beads and the welding sequence is presented. For the benchmark shape, experimental verification of the numerical model is performed. The influence of the distance between the weld beads and the effect of the tool diameter is numerically investigated. Furthermore, the variation in compressive stresses due to temperature fluctuations during the extrusion process has been evaluated. The results showed that adequate compressive stresses are generated on the welded parts through the cladding process after cooling. More compressive stresses are induced in the tool as the cross-section of the weld bead is increased. Furthermore, keeping a gap between the adjacent beads improves tool reinforcement. Hence, the targeted reinforcement of the substrate can be achieved by optimizing the welding sequence and process parameters.

Multivariate steepest ascent method based on latent variables

This paper presents a multivariate steepest ascent method based on the gradient of the first order principal component score model, with direction, step sizes and shifts driven by an integrated variance mapping. Using a random initial center point guess within regions of minimal prediction error, gradual improvements are done towards the curvature region where a response surface may be properly fitted. Experimentations carried out in such regions allow a large step size since coefficients standard error are very low. In order to illustrate this approach, a Flux-Cored arc welding cladding process of AISI 1020 carbon steel sheets with AISI 316L stainless steel tubular wires was studied considering a full factorial design with four input parameters for correlated pairs of responses. The case study and additional simulations highlights the suitable optimization results obtained with the method and its practical and successful implementation in a real-word manufacturing problem.

Simultaneous multi-objective optimization of stainless steel clad layer on pressure vessels using genetic algorithm

Metal cladding is a process of depositing a filler material to enhance the surface properties of base material using a suitable welding process. In this work the clad specimens are produced by surfacing a layer of filler material using weld cladding process to minimize the heat loss across the walls of the pressure vessels. It is done by depositing a low thermal conductivity austenitic stainless steel grade of 316L on structural steel plates used for boiler construction using flux cored arc welding process. The experimental study is carried out as per design of experiments availed for five factors five levels central composite design using response surface methodology. The mathematical models are developed for the prediction of clad layer height, clad layer width and depth of penetration. These models are employed in formulating fitness functions for multi-objective optimization of clad layer dimensions using genetic algorithm (GA). The set of optimal solutions suggested by response surface optimizer and genetic algorithm are compared and discussed. Conformity tests are conducted to validate the prediction capability of developed models and optimum settings. Optimum clad layer dimensions have been arrived and optimized stainless steel clad specimen has been produced. The heat transfer analysis is planned to be conducted in the next phase. The findings can be used in energy efficient design of pressure vessels.

Use of Ultrasound in Reconditioning by Welding of Tools Used in the Process of Regenerating Rubber.

Addressing the problem of reconditioning large parts is of particular importance, due to their value and to the fact that the technologies for their reconditioning are very complex. The tools used to refine regenerated rubber which measure 660 mm in diameter and 2130 mm in length suffer from a rather fast dimensional wear. Within this research, the authors looked for a welding reconditioning procedure that would allow a very good adhesion between the deposited material layer and the base material. In this regard, the MAG (Metal Active Gas) welding process was used, but the ultrasonic activation of the welding process was also considered. Thus, the wire used for welding was activated considering a variation of the frequency of ultrasounds in the range f = 18–22 kHz respectively of the oscillation amplitude A = 30–60 μm. Under these conditions it was found that the presence of ultrasonic waves during the welding cladding process results in uniform deposition of hard carbons at the grain boundary and in the elimination of any existing oxides on the deposition surface, but at the same time increases the adhesion between the base material and the additional material, all of which positively influence the wear and corrosion resistance of the tools used to refine the regenerated rubber.

Investigation of erosion-corrosion behavior of (WTi)C based weld overlays

Erosion-corrosion is responsible for severe damage and high maintenance costs in many industrial operations involving slurry handling such as oil sands and mineral processing. While tungsten carbide reinforced Ni-based alloy overlays are frequently used for applications requiring extremely high wear resistance, they tend to suffer from extensive carbide degradation during the weld cladding process which has been shown to severely impair their erosion-corrosion resistance. Recently, new (WTi)C based overlays are being developed to alleviate some of the limitations associated with the nickel-based tungsten carbide overlays. In this study, three different overlays reinforced with (WTi)C and one tungsten carbide were assessed using a slurry pot erosion-corrosion testing apparatus where the total erosion-corrosion (E-C) rate as well as the separate components of synergistic effect was determined. Erosion-corrosion test was performed at 30°C, in an aqueous slurry containing 35wt% AFS 50–70 silica sand and 3.5wt% NaCl. A special SEM technique was employed to examine changes on the specimen surface at specific overlay locations before and after erosion-corrosion test in order to identify the effect of corrosion on erosion and vice-versa. It was found that tungsten is more prone to dissolution in the matrix during the welding process than titanium, which forms W-depletion/Ti-rich layer around the (WTi)C particle. Dissolution of tungsten and titanium promotes the formation of secondary carbides in the matrix. Erosion-corrosion performance of the overlays largely depends on increased fraction of retained primary (WTi)C phase.

Erosive Wear of Inconel 625 Alloy Coatings Deposited by CMT Method

Abstract The article presents the investigation results concerning the determination of the characteristics of erosive wear caused by the impact of Al2O3 solid particles on the surface of Inconel 625 alloy after plastic working and the same material after weld cladding process using the CMT method. Erosion wear tests were performed at two temperatures: 20°C and 650°C. The erosion tests were conducted using the standard ASTM G76. A jet with a specified abrasive waight was directed to the surface of the tested material at an α impingement angle varied in the range of 30-90° at a velocity imparted to the abrasive by the medium, which was compressed air. The eroded surface was examined using a scanning electron microscope (SEM), while the depths of craters caused by the erosion tests were measured with an optical profilometer. The predominant mechanisms of the formation of mass losses during solid particle erosion were microcutting and microfissuring.

Sensitivity Analysis for Process Parameters in Cladding of Austenitic Stainless Steel by Pulsed Metal Inert Gas Welding Process

In recent scenario, the automation in weld cladding process has a challenging task for most of the industries like automotive, petrochemical and food processing industries. Because to achieve the best quality of the weld clad bead geometry during automated process it is important to have complete control over the selected process parameters. The cladding process enhances the base material properties. Therefore, it is essential to predict the relationship between the process parameters and response the second order polynomial regression equation has to be developed. It makes more effectiveness of automated weld cladding processes. Palani and Murugan [1] developed a mathematical model for a flux cored arc welding process using an RSM method to study the direct effects and interaction effects of process parameters on clad bead geometry.

Study on the Corrosion Resistance of Ti(CN) Composites Coating

Metal composites coating of Ti (CN) was made on the surface of Q235 steel substrate by reaction nitrogen are welding cladding process, and potted with low temperature epoxy, di-n-butyl phthalate and T31, the mass ratio was 10:2:1.5. To evaluate the corrosion resistance of Ti (CN) coating, the specimens were immersed in 5% sulfuric acid and 3.5% sodium chloride to calculate corrosion rate by potentiodynamic polarization measurement. The corrosion resistance of Ti (CN) is improved by 3.45 times in 5% sulfuric acid and 4.39 times in3.5% sodium chloride.

Synthesis of Fe based ZrB2 composite coating by gas tungsten arc welding

ZrB2/Fe composite coating was in situ synthesised by gas tungsten arc welding cladding process on AISI 1020 steel. Zr, B4C and Fe–B alloy powders were used as precursor powders. The phase composition and microstructure were investigated by X-ray diffraction analysis, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Microhardness of ZrB2/Fe composite coating at room temperature was examined. Main phases obtained from Zr and B4C precursor are ZrB2 and α-Fe, and those obtained from Zr and Fe–B precursor are ZrB2 and FeB. In the upper part of these composite coatings, ZrB2 phase mainly grows along temperature gradient direction. The middle part of these composite coatings has the highest ZrB2 content and highest microhardness. Gradient dispersions of ZrB2 reinforcements appeared in the composite coating from the middle to the bottom, leading to gradient dispersions of microhardness. With decreasing dilution rate, ZrB2 content and microhardeness increase.

Study on TiAl(CN) Particle Reinforce Composites Coating Prepared by Reaction Nitrogen Arc Welding Cladding Process

Particle reinforce composites coating of TiAl(CN) was made on the surface of Q235B steel substrate by reaction nitrogen arc welding cladding process, which take the titanium powder, aluminum powder and the graphite powder as original material. The microstructures, structure and the phase of the coatings were investigated by scanning electronic microscope, X-ray diffract instrument, micro-hardness, reciprocating friction testing machine. The result indicated that the TiAl(CN) coating has a metallurgy union with the substrate, the phase of the coatings are mainly composed of TiAl(C 0.51 N 0.12), AlFe3 and FeC. The microhardness and anti-abrasive performance of the TiAl(CN) coating is better than the Ti(CN) coating processed by tungsten nitrogen arc surfacing welding process.

TiCN Cermet Composite Coating Prepared By Reaction Nitrogen Arc Welding Cladding Process

A TiCN cermet composite coating was fabricated on 45# steel substrate by reaction nitrogen arc welding cladding technique. The mixture powder of titanium and graphite was preplaced onto the 45# steel substrate after intensive mixing by star ball-mill and gluing with starch binder. The microstructures and phase of the coatings, interracial behavior between coatings and the substrate were investigated by scanning electronic microscope, X-ray diffractometer. The microhardness distribution of the coating section, frictional coefficient, abrasion loss and wearing surface morphology were investigated by microhardness tester, abrasion machine and scanning electronic microscope. The results show that an excellent bonding between the coatings and the 45# steel substrate is ensured by the strong metallurgical interface and phase of the coatings are mainly composed of TiCN. The highest microhardness of the coatings reaches HV 0.5 810, which is about 3 times more than that of the 45# steel substrate. The anti-abrasive test results show the coating has better anti-abrasive performance than the 45# steel substrate.

Optimization of GMAW Process Parameters in Austenitic Stainless Steel Cladding Using Genetic Algorithm Based Computational Models

Weld cladding is a process of depositing a thick layer of anticorrosive metal on a corrosive substrate surface to impart better corrosion resistance properties. In weld cladding process, the difficulty generally encountered will be the problem of selecting optimum combination of input process parameters to achieve the desired dilution level. Until recently trial and error methods were employed to determine the optimum process parameters, which result in wastage of cost and time. This paper focuses on optimization of GMAW process parameters, which are used for deposition of austenitic stainless steel on low carbon structural steel plates. Experiments were conducted based on four-factor five-level central composite rotatable design with full replication technique. Mathematical models relating to gas metal arc welding process parameters to clad bead geometry were developed using multiple regression method. Developed mathematical models are helpful in predicting the clad bead geometry and in setting process parameters at optimum values to accomplish the desirable dilution level at relatively low cost with a high degree of reproducibility. The accuracy of the results was tested by conducting conformity tests using the same experimental set up. Moreover, Genetic Algorithm tool with GUI available in MATLAB 7.0 was used to optimize the process parameters to achieve optimum dilution.