Vertical Welding Research Articles

Investigation of deposition welding in vertical and horizontal position with a coaxial laser wire welding head

Deposition welding of components using the laser metal deposition (LMD) process is a proven method of creating 3D structures. It is used for the manufacturing of components, the repair of machine parts and for cladding. Up to now, claddings have mainly been investigated in the flat welding position. Some investigations on deposition welding in vertical orientation are available with different processes. For the cladding of large components, welding in the vertical direction offers advantages. So far, there are no investigations on the LMD process with coaxial wire feeding when welding in vertical direction. Therefore, in this study, the influence of the welding direction, i.e., vertical down and vertical up weld seams, and the influence of the welding speed are investigated. Single weld seams, claddings and a wall are welded. A stable welding process could be achieved for a welding speed parameter window of 100 to 1000 mm/min. The results show that there is a statistical correlation between the welding direction and the waviness of the weld seams. Vertical up weld seams have a lower waviness. Another influence on the waviness is the welding speed. As the welding speed decreases, the waviness increases. The weld seam geometry is strongly dependent on the welding direction. With vertical down weld seams, the width and height of the weld seam vary depending on the distance welded. This can be attributed to the influence of the gravitational force. Vertical up weld seams, on the other hand, have a more uniform shape.

Gravity effects on temperature distribution and material flow in the keyhole pool of VPPA Al welding

This study investigated heat and mass transfer as well as the effect of gravity on keyhole formation in the molten pool of keyhole plasma arc welding. The flow trajectory of the molten pool was obtained via high-speed camera images illuminated by a laser light system, and the temperature distribution was obtained using an infrared thermal camera. The experimental results showed that the molten metal flowed rearward and downward at the top surface of the weld pool and thereafter to the rear side of the keyhole. There are two types of reverse flow of molten metal on the rear side of the keyhole. The different welding positions had minimal effect on the flow pattern; however, the flow velocities were different. Further, for the temperature distribution, although the keyhole front side yielded a similar high-temperature area under different welding positions, the area of the high temperature on the keyhole rear side in the vertical position welding was much larger than that in the flat position. Consequently, the influence of the force on the keyhole molten pool was evaluated, and the flow pattern of the molten pool was found to be dominated by the sheer force. Moreover, the flow velocity and solidification morphology of the molten pool were affected by the gravity at different welding positions. In addition, the correlation mechanism of the temperature distribution, flow, and solidification morphology of the keyhole molten pool was analyzed using the combined action of shear force and gravity, which further revealed the mechanism of the influence of gravity on the keyhole welding process.

Buckling behavior of double skin composite walls under axial compressive load

In this paper, the steel faceplate buckling of double skin composite walls stiffened with studs or steel-bar trusses is studied and analyzed by the axial compressive test, including ten specimens. According to the investigation, the buckling mode of steel faceplate, whose restraint situation is four points arranged in different shapes, is observed, and the calculated equation of buckling stress is proposed. Based on the test, the buckling strain monitored by strain gauges and maximum strength increases with the decline in welding spot spacing-to-thickness ratio and spacing aspect ratio. According to the finite element model (FEM) established by ABAQUS, the failure mode of the walls is simulated well. The buckling stress and load–displacement curve obtained by FEM corresponds well with these of the test. The parametric analysis is conducted to study the influence of initial geometric imperfection by considering the welding spot spacing-to-thickness ratio and spacing aspect ratio on faceplate buckling stress. When the initial geometric imperfection is larger than 1/1000 of the vertical welding spot spacing, the faceplate buckling stress drops more slowly with the increase of initial geometric imperfection. The relationship between the buckling stress and welding spot spacing-to-thickness ratio obeys the Euler curve. The buckling stress of the steel faceplate decreases linearly with the increase in the spacing aspect ratio. The results by using the buckling equations with the consideration of the initial geometric imperfection and spacing aspect ratio are approximately in accordance with the simulated results.

Effects of Ternary Shielding Gas on Weld Characteristics of All-Position Welding for Pipelines

As an efficient welding method, Gas Metal Arc Welding (GMAW) has the advantages of low thermal energy input and stable mechanical properties of ring weld joints. GMAW has now become the main welding method for large-diameter oil and gas pipelines. Narrow gap welding is widely needed in pipeline manufacturing, yet lack of fusion on side walls is often produced in this process when conventional binary shielding gas (Ar–CO2) is used. Here, we use a ternary shielding gas (Ar–CO2–O2) to improve the weld formation of all-position narrow gap welding of pipelines. The weld formation and weld penetration depth of the pipe welding at 0 o’clock (flat welding), 3 o’clock (vertical welding), 6 o’clock (overhead welding) are investigated. Macroscopic metallographic analysis on the melt width are carried out, and feasibility of the ternary shielding gas is illustrated. Comparing to the binary shielding gas, the ternary shielding gas leads to better weld formation, weld width and weld penetration. Especially, the weld penetration depth can increase by 20%, which helps to reduce the lack of fusion.

The effect of excessive penetration of welding on sand erosion pattern due to high speed gas-solid flows in elbows and reducers

The aim of the current study is to investigate the effect of excessive penetration of welding and natural gas impurity particles on increasing erosion in elbows and reducers. To this end Euler–Lagrange model is used to simulate the two-phase solid–gas flow, the Discrete Phase Model (DPM), k-ε turbulent model and DNV erosion model are used to model the solid particles, natural gas flow and erosion rate, respectively. Erosion in elbows occurs downstream of vertical welding while in reducers is weaker and occurs at the inlet. The results show that erosion rate increases by increasing excessive penetration, particles size, particles flow rate and natural gas flow rate. The effect of excessive penetration becomes more important in high speed flows containing solid particles, in such a way that reducing excess penetration from h = 3 mm to h = 0 mm, causes 45% reduction in erosion rate in elbows containing 20 m/s natural gas flows. Therefore, for high velocity impure gas flows, it is recommended to reduce the allowable excessive penetration in welding standards.

Suppression of Bottom Porosity in Fiber Laser Butt Welding of Stainless Steel

The application bottleneck of laser welding is being gradually highlighted due to a high prevalence of porosity. Although laser welding technology has been well applied in fields such as vehicle body manufacturing, the suppression of weld porosity in the laser welding of stainless steel containers in the pharmaceutical industry is still challenging. The suppression of bottom porosity was investigated by applying ultrasonic vibration, changing welding positions and optimizing shielding gas in this paper. The results indicate that bottom porosities can be suppressed through application of ultrasonic vibration at an appropriate power. The keyhole in ultrasound-assisted laser welding is easier to penetrate, with better stability. No obvious bulge at the keyhole rear wall is found in vertical down welding, and the keyhole is much more stable than that in flat welding, thus eliminating bottom porosity. The top and bottom shielding gases achieve the minimal total porosities, without bottom porosity.

The capacities of thin plated stiffened T-stubs

The stiffeners, also known as ribs, have a great influence on the behavior of the extended end-plate connections. The end-plate connections can be idealized by making use of equivalent T-stubs. The effects of the stiffener on the behavior of T-stubs were experimentally investigated with an extensive set of parameters. Flange thickness, flange width, gage distance, distance from a T-stub stem to bolt row, vertical edge distance, bolt diameter and weld thickness are selected as the parameters. Pursuant to this goal, 44 stiffened T-stubs were tested under monotonic loading up to failure. The load-displacement curve of each T-stubs is presented and the results are evaluated with the predicted capacity by AISC 358 and EC3. The results revealed that the current provisions underestimate the capacity with high standard deviations. Therefore, a new design expression is proposed utilizing the yield line mechanism to estimate the plastic capacity more accurately. Moreover, an expression is developed to predict the ultimate capacity.

Impacts of vertical salt welding on pore pressure, stresses, and deformation near the weld

We use a forward finite-element model to explore pore pressure, stresses, and deformation near a vertical weld. Dipping layers of mudrocks interbedded with a mixture of basin-center and basin-wide sand layers are deposited sequentially over a salt layer. After a salt wall rises at the downdip end of the model and emerges at the basin surface, shortening is imposed on the system until the salt wall almost welds where the wall feeder is narrowest (waist). Welding causes a significant increase in horizontal stress, which results in increased pore pressure near the weld. The pore-pressure increase adversely affects hydrocarbon accumulation and drilling near the weld because it: 1) causes remigration of pore water downdip along sand beds cresting near the weld, 2) decreases the hydrocarbon-column capacity of these beds, and 3) narrows the mud-weight window for drilling wellbores near the weld. The least principal stress near the weld is almost vertical and equal to the overburden stress in mudrocks, but horizontal and significantly lower in sand beds. Welding of the salt wall causes steepening of flanking strata and shortening of the weld wall rocks. The impacts of welding begin at a waist width of 1.35 km, long before the salt wall welds.

Analysis of Tensile Strength of Inert Gas Metal Welding on Aluminum 5083 with Variations in Argon Gas Current and Discharge

In the technology industry, metal raw materials such as steel and aluminum have an important role in the production process, as so far there is no metal that cannot be joined by welding. Metal Inert Gas (MIG) welding method is a gas arc welding that uses a welding wire as well as an electrode. In the Metal Inert Gas (MIG) welding process, the heat from this welding process is generated by a welding arc formed between the wire electrode and the workpiece. The purpose of this study was to determine the tensile strength of the welding results in the connection process with Metal Inert Gas (MIG) against aluminum (Al) 5083 series 6 mm thick, the welding was carried out with various current strength treatments, namely 120 A, 130 A, 140 A. and Argon gas discharge 5 lt/minute, 10 lt/minute, 15 lt/minute in each welding process. This research is useful to know and understand about the analysis of the welding process on aluminum 5083 with a thickness of 6 mm with Metal Inert Gas (MIG) welding process using vertical (3 grove) welding techniques. The method used in this study is the analytical method, which is a method for testing by adding different treatments of current and discharge variations of Argon gas during the welding process of the specimen, so that different welding strengths will be obtained in each specimen.

Forming characteristics and mechanism of double-sided heat source synergic vertical welding on an aluminum alloy

Top-quality aluminum alloy weld beads, exploiting the double-sided heat source synergic welding (DSHSSW) process, were obtained with medium heat input, no arc spacing, no root gap, and upward vertical direction. The energy utilization was reduced with the augmented arc spacing because of the attendant increased heat dissipation. Compared with one-side welding (OSW), the fusion area and melting efficiency of DSHSSW were enormously raised, indicating the enhancement of melting performance and energy utilization, and superior joints could be fabricated using DSHSSW under the identical heat input. Additionally, the DSHSSW arc was constricted and thus improved the energy density in contrast to OSW. As the weld penetration deepened during DSHSSW, the heat conduction space was diminished, and the heat accumulation effect was generated. The arc contraction and heat accumulation effect mutually lead to the increased penetrating ability during DSHSSW.

Research on influence of Web spacing of bogie side member on welding deformation

In the production process of bogie, welding is one of the important production technologies. To study and control the welding deformation of bogie frame side beam to make the deformation value within a reasonable range has very important practical significance for the production of bogie side beam. The research content of this paper will take high-speed EMU bogie frame side beam as the research object. Set different web spacing, compare the welding deformation value, explore the influence of structural stiffness on the welding deformation of side beam, and use MATLAB software to curve fitting the welding deformation value, the research shows the distribution law of transverse, longitudinal, vertical and comprehensive welding deformation, and fits the mathematical equation between the web spacing L and longitudinal deformation SX, vertical deformation SY, transverse deformation SZ In this paper.

Причины образования трещиноподобных дефектов в толстолистовой стали 09Г2С для резервуарных металлоконструкций

Determination of causes of crack-like defects in the heavy plate steel 09Г2С is a crucial task, the solution of which is aimed at improving the mechanical safety of oil storage steel vertical tanks. In order to determine the causes for the formation of a group of crack-like defects oriented towards rolling, revealed during grinding and magnetic inspection of the tank wall surface near the vertical weld, the analysis of the chemical composition and testing of the mechanical properties of heavy plate steel were carried out, including the determination of the anisotropy of impact toughness in the temperature range from +20 to –75 °С, analysis of metal microstructure in the area of defect formation on transversal sections and rolled surface. Impact bending tests of 09Г2С heavy plate steel after controlled rolling in longitudinal and transverse directions showed no anisotropy of impact toughness, as well as high purity of steel as for sulfur and titanium, which at higher content causes impact toughness anisotropy. The revealed features of metal microstructure near the defects made it possible to conclude that the crack-like defects were formed during the rolling of gas bubbles at the stage of preparing semi-finished rolled products for finishing rolling. One of the possible methods to prevent such defects from getting into finished rolled products is the use of automated systems of visual inspection of rolled products in the manufacturing process.

Ertical Butt Welding Technology of Q355g Small Diameter Pipe TIG

In this paper, according to the requirements of welder's technical qualification specification, combined with the practice training topic of TIG vertical butt welding, we have repeatedly trained the operation process of TIG vertical butt welding of q355g steel pipe with specification of Φ 60 х 5,And we adopt the following process measures in the welding process: before welding, we make V-shaped tooling by combining with the workpiece ; when welding, we choose reasonable process parameters; at the same time, we pay more attention to the welding operation skills of backing and cover layer. Therefore, we have achieved satisfactory weld quality, and the relevant experience has been popularized in the teaching process of the school to obtain good evaluation.

Comparative study of energy distribution and interface morphology in parallel and double vertical explosive welding by numerical simulations and experiments

Different from the traditional parallel method, double vertical explosive welding adopts a closed charge structure, and two composite plates are formed by one explosion. The energy distribution and interface morphology in the parallel methods and double methods were studied by numerical simulation and experiments. The theory of “energy flow in stages during explosive welding” was first proposed and energy balances at the start and end welding were obtained in this paper. The temporal and spatial distribution of the relevant parameters was analyzed. The value and proportion of each energy were calculated in sections by numerical simulation. The results showed that the detonation products in double method had higher internal energy and lower kinetic energy. The collision velocity obtained by the two methods was close. The kinetic energy of the flyer plate, plastic deformation energy and jet energy in the double method were about twice those in the parallel method. The experimental results showed that the dimension of the interface waves in two methods was close, but more melted microstructures were observed in the double method, whose compositions were mainly TiFe2 and TiFe3. Double vertical explosive welding improved energy efficiency and saved at least half of the explosives.

Design and Fabrication of Fixture for Rotary and Vertical Welding

Design and Fabrication of Fixture for Rotary and Vertical Welding

Study the Effect of Welding Position and Plate Thickness to the Mechanical and Microstructural Properties of the TIG Dissimilar Metal Welded between Carbon Steel ASTM A36 and Stainless Steel 304 Plates

Dissimilar metal welding was mostly done to optimize the application and engineering requirements with economic considerations. Weld microstructures greatly influenced the mechanical properties of welded joints. The investigations were carried out to evaluate the microstructural and mechanical properties of dissimilar weldment between carbon steel ASTM A36 and austenitic stainless steel 304 with a variation of welding position (1G, 2G, 3G) and weld thickness (6 mm to 12 mm) joints by TIG welding. A detailed analysis was conducted on the weld zone composition, the microstructural, and mechanical properties. The results show that the welding position and thickness of the weld joints influenced the microstructure both in HAZ and weld metal. Size, distribution, and orientation of microstructure were improved and more uniform with increasing of welded joint thickness. In HAZ carbon steel, GB ferrite was dominant, especially for the flat welding position (1G), while for the horizontal position (2G) and the vertical welding position (3G) showed other structures such as Widmanstaten ferrite, hard-structures like martensite and bainite. In the region near the fusion line and the weld metal, the chemical composition changed due to thermal convection, diffusion, and macro-segregation caused by penetration of liquid metal carbon steel into the weld pool. SEM/EDS results indicated diffusion of carbon from carbon steel A36 to stainless steel 304 and formed the hard-structure along the fusion line. The mechanical test results showed that the tensile test breaking point occurred in the parent metal of carbon steel A36. The bending test results showed very high stress on the face side of the welding joint, and there are no cracks from the bending test result. Vickers hardness testing showed that the hardness distribution increased from the carbon steel HAZ to the stainless steel HAZ, and the maximum hardness has achieved the value of 297 Hv at the fusion line of stainless steel 304.

Rational design solutions of ensuring the walls of tanks stability to the action of transverse loads

The article considers the task of an integrated approach to the study of the rationality of strengthening the cylindrical walls of large volume tanks with stiffening rings under transverse loads. Based on the results of computational studies, the principles of placement and rational boundaries usage of stiffening rings for vertical cylindrical tanks of various volumes are determined. The results were obtained for ideal shells and for cases of the presence of a typical geometric wall defect in the form of the angularity of a vertical weld. To validity the reliability of the results obtained, an experimental verification of the numerical model was carried out.

Development of phased array ultrasonic system for detecting rail cracks

In this study, a phased array ultrasonic system for detecting rail cracks (PAUSR) was developed which consists of two phased array (PA) ultrasonic transducers, a water tank, a display monitor, a battery, a commercial 64 channel PA board, and its control software. To accomplish this, the acoustic fields and crack detection images of newly developed PA ultrasonic transducers were simulated and analyzed by the CIVA (CIVA 2016, NDE CIVA, USA) software. The major design factors for the PAUSR is the capability of evaluating crack size (over 2 mm), generating proper acoustic fields in the rail and easy and safe handling for operators. For the performance test of the designed PA ultrasonic transducer, Non-destructive Characterization and Verification of Ultrasonic Phased Array Equipment, Part 2: Probes (EN ISO 18563-2:2017) was conducted. In addition, artificial crack detection images were simulated by the CIVA software, and an experiment under the same CIVA simulation conditions was also performed for comparison purposes. For the last verification, natural defective specimens with bolt-hole star-cracking, longitudinal vertical cracking and welding defects were scanned by the developed PAUSR, and its results were analyzed and compared with the radiographic testing (RT) and CIVA simulation outcomes.

Pore Formation during Laser Welding in Different Spatial Positions

The process of formation of pores, cavities and similar defects in welded joints of stainless steels and aluminum alloys, affecting their quality, directly depends on spatial weld position in laser welding. Reducing the angle of inclination from 90° to 0° during downhill and uphill welding of AISI 321 stainless steel in the pulse mode of laser generation leads to an increase in both the number of pores and their size. At the same time, defects in the form of pores are not observed in the continuous mode of laser generation. In laser welding of butt joints of AISI 321 steel, the flat and vertical weld positions are the most promising, as they provide the highest level of quality. In order to provide a stable formation of a high-quality butt joint of aluminum AMg6M alloy and to prevent the failure of laser equipment, the welding process should be carried out in a vertical uphill weld position.

Macro and microstructure evaluation of TIG weld on DSS (2304) with bead geometry at three positions

Duplex Stainless Steel (2304) steel plates of 6 mm thickness have been fabricated by one-side butt welding procedure employing Tungsten Inert Gas welding process at three different positions (i.e. Flat, Horizontal and Vertical). The effort of welding position on Macro-section and Microstructure of TIG welded specimen was observed. The welding current, filler material and speed was optimizing by carefully evaluating weld geometry and microstructure of different welding positions. Design of experiment was carried out using Taguchi technique to optimize the process parameters of welding. The input variable process parameters are welding current, speed, filler material and welding position, whereas output parameters are weld width, reinforcement, penetration and wetting angle. The experimental results illustrate that the joint of horizontal weld has more reinforcement and microstructure and macro-section includes three zones: weld zone, heat affected zone, thermal affected zone showed that unsymmetrical weld interface and thermo mechanically affected zone boundary was found in horizontal and vertical position joints. The formation of fine grains with less fusion area and less reinforcement were found in flat welding positions. Form all the samples it was found that the heat affected zone area, fusion angle and wetting angle is more for vertical position welding specimens. By analyzing macro-section and microstructure of joints it was observed the fusion area at root gap for vertical weld is three times more compared to flat welding position and root penetration is more at high welding current. It was found that the migrated grain boundaries are formed on the weld zones for all the weldments.