Welding Process Design Research Articles

Characteristics of welding laser beam and its influence on weld forming coefficient

Laser welding is a very complicated process. At present, there is no systematic research on the relationship between welding parameters and forming coefficient. By studying the internal relationship between laser parameters and the characteristics of welding laser, laser beam indexes, such as focusing index, are defined. They are simplified to a few laser parameters so as to facilitate the study of the influence of welding parameters on the forming coefficient. The results show that material, assembly gap, laser power and welding speed have great influence on weld penetration. When the laser power density reaches 106J/cm2, the characteristics of deep penetration welding appear. Under the condition of constant clearance, the weld depth increases with the increase of t/b. The weld penetration increases with the increase of laser power and tends to be stable when the welding speed is 12mm/s. Different materials also have a certain influence on the weld penetration depth. Under the same conditions, X6CrNiTi1810 obtains greater penetration depth, indicating that physical and chemical properties of materials are also one of the factors affecting the penetration depth. The mechanism and condition of laser welding were analysed. The relationship between laser absorptivity of sheet surface and physical properties of the materials is also studied and then obtained. The study will provide theoretical guidance for laser welding process design and welding parameter selection of steel plate.

Plasma characteristics of a novel coaxial laser-plasma hybrid welding of Ti alloy

A novel coaxial laser-plasma hybrid welding method defined as “laser-soft plasma coaxial hybrid welding” was developed and studied. The plasma characteristics evolution, including plasma morphology, static electrical characteristic, and physical information of this welding method, was studied with the based material of TC4 alloy. Laser welding and plasma welding were carried out and used as comparative experiments. The plasma morphology of hybrid welding combines the characteristics of laser-induced plasma and arc plasma. The static electrical characteristic indicates that laser and plasma interact and influence each other but with different mechanisms under different current conditions. Physical information such as plasma electron temperature and ion density show that composite plasma can rapidly increase the heat source energy and ionization rate. To sum up, the coaxial plasma arc can increase the laser effect and redistribute the heat of the compound heat source, leading to a widened bead weld and better welding gap adaptability. This work provides an effective method and reference for hybrid welding process design and control in the practical industry.

Analysis of Welding Technology about Bimetallic Clad Pipelines

Butt girth welding was a knotty problem for future application of bimetallic clad pipelines. At present, there were two kinds of problems: 1) To decide whether to use a variety of alloy welding procedure or to use corrosion resistant alloy full welding procedure; 2) After selecting the procedure, what kind of welding material should be equipped. In view of the above problems, taking 316L SS or 2205 DSS clad pipe as an example, welding process design and experimental analysis were conduted in this paper. Analysis of welding process from theory, standard and practice pointed out the control of welding hardness under different welding materials and procedure and directional suggestions of welding for bimetallic clad pipelines were provided. Futher the hardness distribution and CVN absorbed Energy test results of different welding processes showed welding quality could be guaranteed only when ENiCrMo-3 welding material was chosen for the whole weld.

3D Computational Welding Mechanics applied to IN625 Nickel-Base Alloy

Design for sustainability asks for higher and higher performance materials and enhanced techniques devoted to realizing their joints. For advanced applications, the emphasis is on high-temperature strength, long-term creep life, phase stability, oxidation resistance, and robust and flexible welding processes. In this scenario, Ni-based superalloy Inconel 625 is successfully used for mechanical components operating at high temperatures and stresses, conditions that however may cause surface cracks. In the frame of circular economy, fusion welding is therefore used as a convenient repairing technique, as well. However, correct process parameters avoiding metallurgical and mechanical defects need to be known for each case-study. Computational welding mechanics is a proper tool used to avoid expensive trials, provided that the used numerical model can capture the main phenomena involved in welding process. In this work, a 3D numerical model of Inconel 625 multi-pass welding process is developed and validated through residual stresses X-Ray diffraction measurements. The model showed a good accuracy and was therefore proved to be a powerful tool for welding process design of such alloy.

A novel field box girder welding robot and realization of all-position welding process based on visual servoing

Abstract Box-type steel structure has been widely applied in the field of buildings and bridges because of its unique advantages. However, there are still many problems in field welding that need to be solved. In order to improve the level of automation and intellectualization in field welding of box girder, a new type of on-site all-position welding robot system is developed and designed in this paper. The convenience of on-site installation and debugging of the robot is realized by the scheme of permanent magnet adsorption and straight-arc combined track. The motion matching scheme of bilateral wheel-axle clamping makes the circumferential movement of the robot much smoother and more stable which makes the system with better overall force characteristics and load-carrying capacity. Then, a novel visual sensor based on combined laser structured lights is proposed and designed, which can realize several functions such as groove parameters detection, welding joint tracking and torch posture detection in field welding based on single detection image, so as to effectively improve the flexibility and intelligence of field welding robot. After that, based on the designed visual sensor and welding robot system, a visual servo-control system based on Visual Studio platform is established. Through the effective integration of detection image reading, image processing and calculation, image feature parameters transmission, motion control board call and feedback control signal output, the adjustment and control of welding torch's position and posture based on visual servo-control are realized. Furthermore, based on the kinematics calculation and the welding process requirements of the box girder, the welding process design is planned for the all-position welding of the box steel girder, which solved the technical problem of the rectangular fillet welding in the box steel butt welding (the welding torch position and posture transition control in right-angled corner of girth butt joint). Finally, all-position welding experiments of box steel girder were carried out. The results show that the welding robot based on visual servo-control can realize better control of weld formation in all-position welding of box steel girder.

Mechanical Response and Performance Relationship of X70 Pipeline Steel with Weld Zone

With the development of the natural gas industry, high flux natural gas pipelines will cause local deformation because of pressurization, which has an important effect in the service safety of pipeline materials. In this paper, the X70 pipeline steel with weld zone was studied, and the tensile test was used to simulate the uniaxial tensile stress. The results showed that the strain was mainly concentrated in the weld zone, which can imply that the weld zone has high strain hardening ability. The heat-affected zone with poor internal structure was prone to breakage. The research results can provide theoretical basis and experimental basis for pipeline steel welding process design and safety evaluation under high flux conditions.

Energy Saving Analysis of No-load Loss of Electric Welding Equipment

In this paper, two types of electric welding equipment are studied. First of all, YD / k-505fl4 and bx3-500 type welding machines do not have the function of self power off in standby state. It is necessary to install an intelligent welding machine power saving system to control the power off of the primary side of the transformer under the no-load state of the welding machine, and then cut off the no-load loss of the welding machine. Secondly, yd-500-kr II series welding machine has the function of standby, delay and self power off. Due to the unreasonable setting of welding parameters, the uneconomical selection of welding cable and the unreasonable layout of welding machine, the overall energy loss of welding machine is large. Finally, weathering steel is used in the welding process design, and the performance, energy consumption and economic practicability of the material are analyzed.

Application of Automatic TIG Welding for Yamal LNG Process Piping Fabrication

The representative materials, used in Russian Yamal LNG project, are ASTM A333 Gr.6 (low temperature carbon steel, designed temperature of –50°C) and ASTM A312/A358 TP304/304L (austenitic stainless steel, designed temperature of –196°C). The welding technical specification demands TIG (Tungsten Inert Gas) welding for root welding of piping. This project adopts the construction way of prefabrication in Qingdao and assembly in Russian. Therefore, high construction accuracy is required. This article introduces the LNG process piping welding by automatic TIG welding which contains welding process design, welding process parameters, test and analysis of weld mechanical property and advantage analysis of TIG welding as well. In this project, the automatic and high efficient TIG welding is used for the root welding and hot welding of low temperature carbon steel and austenitic stainless steel piping. The result shows that the mechanical properties of weld metals meet the requirements of LNG project technical specification and code ASME B31.3. The efficiency of automatic TIG welding increases 2 times compared with conventional manual TIG welding. The automatic TIG welding improves and optimizes the quality and construction progress of the LNG project process piping.

Modeling and experimental study of laser welding distortion of thin metallic bipolar plates for PEM fuel cells

Laser welding is the most effective joining method for thin metallic bipolar plates (BPPs) to achieve reliable seal and fulfill the requirements for fuel cell stacks. However, distortion caused by the welding heat will produce shape error in BPPs. The shape error will cause uneven assembly stress distribution and unacceptable contact resistance between BPPs and the gas diffusion layer (GDL), eventually affect the fuel cell performance.In this study, transverse deformation and angular distortion are considered to be the main sources of BPPs shape error and studied by modeling and experimental methods. An analytical model based on inherent strain theory is established to predict the transverse deformation of BPPs. Meanwhile, a model based on the weld pool geometry is proposed to evaluate the angular distortion. Experiments are performed to validate the models by welding 316L stainless steel sheets of 0.1 mm and 0.2 mm thick with a multi-mode fiber laser system. A good correlation is found between experimental results and the prediction models. Finally, a formula based on the former prediction models is proposed to calculate the welding induced shape error of BPPs with two pass welds. The formula is validated by experiments. The methodology in this study can be applied to guide the laser welding process design and manufacturing of the metallic BPPs.

Study on the Structure of the Alloy Welding Mold and the Welding Specifications

ordinary carbon steel hardness and life is difficult to achieve blanking dies and drawing dies requirements. In the surfacing alloy steel and alloy steel base can improve the surface hardness and durability of the mold. To reduce the use of electric arc welding carbide decomposition and burn in the shielding gas . Welding mold base structure to meet the requirements of the welding . Mold heat treatment after welding specifications and hardness to meet the processing requirements and use of strength requirements. Welding process design mold substrate heating requirements and the requirements of the solder layer thickness and the thickness between layers allocation.

Process parameter optimization of lap joint fillet weld based on FEM–RSM–GA integration technique

This study introduces a welding process design tool to determine optimal arc welding process parameters based on Finite Element Method (FEM), Response Surface Method (RSM) and Genetic Algorithms (GA). Here, a sequentially integrated FEM–RSM–GA framework has been developed and implemented to reduce the weld induced distortion in the final welded structure. It efficiently incorporates finite element based numerical welding simulations to investigate the desired responses and the effect of design variables without expensive trial experiments. To demonstrate the effectiveness of the proposed methodology, a lap joint fillet weld specimen has been used in this paper. Four process parameters namely arc voltage, input current, welding speed and welding direction have been optimized to minimize the distortion of the structure. The optimization results revealed the effectiveness of the methodology for welding process design with reduced cost and time.

Co-Design Research on the Welding Structure of the Metro Bogie

In order to study the influence of welding process and local detail design to the life of the metro bogie frame, this paper, in view of the tee joint, researched the superposition of residual stress and external load influence on the structure strength by the finite element simulation to establish mechanical structure and welding process co-design method. Based on the above research, the fatigue strength of the overlapping structure of welding frame socket plate and beam was improved, by the co-design of the groove angle and joint-welding sequence.

Laser pulsed welding in thin sheets of Zircaloy-4

A simulation technique for the welding process design to obtain the high reliability of nuclear fuel spacer grids is presented. A finite element model of pulsed laser welding for Zircaloy-4 plate is developed, which incorporates the phase transitions and the dynamic material properties with transient temperature. The effects of pulsed laser parameters on the pool shape and welding-induced distortion are analyzed by simulations and verified by experiments. The parametric study presents that the welding induced distortions are highly dependent on the geometry of the molten zone and the heat affected zone.

Software for PID Design: Benefits and Pitfalls

The most common PID design methods in industry are based on formulas. This article will present some major advantages of instead using the power of computer based softwares for PID controller design. The Matlab based software used in this work was developed in 2007 and derives robust, IAE minimizing, PID controllers. The experiences of using this software are collected in this article and include control signal activity limitation due to measurement noise, controller design on an industrial Friction Stir Welding process and fast controller design for large batches of processes. It is shown that the properties of the software make it suitable for design of PID controllers and in PID research. There are, however, some possible design pitfalls that the user needs to be aware of. Some of these are presented as well.

Core Competencies in Vocational Welder Worker: Based on Thai Welding Industry Participator Perceptions

A core competency facilitates the identification of training needs and guides the design of a professional development program. Thus, this research was to explore and examine the core competencies in vocational welder worker based on Thai welding industry participator perceptions. To synthesize core competencies first used the focus group technique with 17 experts to identify their perspectives on core competencies in vocational welder worker. After that competencies questionnaire survey was developed to collect data from a participator sample consist of , 206 welding industry participators. Research methods were applied to collect quantitative data using questionnaires, forms, interviews, discussion groups and workshops. The resulting analysis revealed that the main elements of the competencies in vocational welder worker could be divided into three core competencies categories, namely: 1) The knowledge and skills generally: Basic skills and Information technology skills 2) The knowledge and skills specific: Process of connection and control, Welding process design, Metal structuring, The selection of proper welding process, Welding control, Inspection and testing process piece, Drawing and design product, Handmade sheet metal product, Produce and control manufacturing, and Pipe installation 3) The attitude: Personalities and human relation.

Numerical procedure for residual stresses prediction in friction stir welding

The prediction of residual stresses is a relevant and, under many points of view, still open issue for a proper welding process design. In the present paper a 3D FE model, with general validity for different joint configurations, was used to simulate the Friction Stir Welding (FSW) process of butt joints through a single block approach. The model is able to predict the residual stresses by considering thermal actions only, thanks to a new time efficient approach. A good agreement between calculated and experimentally measured data was found; the effectiveness of the presented numerical procedure was evaluated by comparing the calculation times of the proposed method with the ones of already known FE approaches.

Numerical analysis of projection welding on auto-body sheet metal using a coupled finite element method

A comprehensive finite element method employing a subroutine to link up submodules of commercial code ANSYS is proposed to perform analysis of projection welding in quantitative detail. In order to solve the complexity due to dynamic changes in heat and electrical current flow paths, as well as temperature-dependent material properties, information about contact interfaces and the geometry of the projection areas have been taken into account. By updating parameter information among these submodules in an incremental manner, a truly thermal-electrical-mechanical coupled numerical analysis is realized for projection welding simulation. A case study of an automotive door assembly welding process is carried out and a series of experiments is conducted to confirm the validity of the newly developed method. The agreement between the experimental and numerical results is satisfactory, indicating that the incrementally coupled finite element method may be suitable for projection welding research. Finally, future work to extend this method in optimizing projection welding process design is also presented.

Significant system parameters influencing HAZ properties in 9%Ni steel

The relative influence of welding system parameters on the properties of the heat affected zone (HAZ) in 9%Ni steel has been investigated via a fractional factorial experiment. The HAZ properties evaluated were the dimensions in two locations, the hardness, and the impact strength. The independent variables were bevel preparation method, welding process, heat input, plate thickness, joint design, and position of the weldment. The study indicated that heat input, bevel preparation method, and an aliased interaction between the bevel preparation method and the joint design must be controlled to minimise the extent of the HAZ at the plate surface. The width of the HAZ measured at plate mid-thickness is a function of plate thickness, heat input, and two aliased interactions: between welding process and joint design; and that determined for the surface HAZ (interaction between joint design and bevel preparation method). Hardness was significantly affected by thickness, welding process, position, and heat input as well as by an aliased interaction between thickness and joint design. Impact strength was most influenced by two aliased interactions, both including the bevel preparation method. Weld position was found to affect HAZ impact values significantly.