Development Of Welding Process Research Articles

Development of laser-arc hybrid welding process of butt joint for bogie pipe crossbeam components

High-speed railway vehicle bogies are the main load-bearing components, which are welded together from steel plates and tubes. Butt joint and T-joint are the main types and the joint thickness is between 8–20mm. The stability of laser-arc hybrid welding (LAHW) process correlated strongly with keyhole behaviour. In this paper, the common quality defects in full penetration root pass by LAHW were analysed. Controlling the root gap is adopted to stabilize the keyhole, to improve the stability of weld quality. A novel type of butt joint with micro structure based on Y-shaped grooves has been designed, to meet both the requirement of controlling root gap and industrial large-scale batch production. Two new structure parameters, 2 mm of the remaining blunt edge thickness and 0.3 mm of the half width of root opening, were proved by the flat plates welding test. Finally, the joint with micro structure and the root pass welding parameters were transferred to the welding process of tube crossbeam components. The LAHW process verification was completed, and the test results showed the process meets the requirements of ISO 15614.

3D‐printing with steel on thin sheets for application in free form façade construction: welding process development and material properties

AbstractWire and Arc Additive Manufacturing (WAAM) became a significant research field in structural engineering over the past years. It offers the opportunity to apply material fast and precisely, following the load path, inducing effective material consumption. Considering free‐formed sheet‐metal façades, to date large thicknesses are necessary to maintain the final shape and load‐bearing capacity that however causes high material consumption and costs during the construction processes. Hence, WAAM could be an opportunity to reduce the amount of mild steel used for free‐form façades. As part of a research project at TU Darmstadt, 1 mm thick free‐form sheet‐metal façades elements have been manufactured using WAAM. Due to precisely welded lattice structures, placed on the backside of the metal sheet, the reinforcement will be ensured. Wide studies on welding parameters focused on a stable process without damaging the later frontside of the façade panel and on process optimization. In addition, material properties of the welding material have been determined to check its usability in façade construction.

Electron Beam Welding Process of Port Stub of CFETR Vacuum Vessel Sector Mockup

Port structures are important parts of vacuum vessel (VV) in China Fusion Engineer Test Reactor (CFETR), which consists of port stubs and port extensions, mainly provides channels for the installation and maintenance of internal components, such as divertor and blanket, and provides interface for auxiliary heating system, diagnostic system, and vacuum pumping. A 1/8 VV sector mockup with port structures is used to explore the key manufacturing technology of CFETR VV. Electron beam welding (EBW) process development of port structures of 1/8 VV sector mockup is introduced in this article taking the inner shell of upper port stub as an example. Through EBW test and process optimization, the surface formation, microstructure, and mechanical properties of the weld are obtained. On this basis, the EBW of the inner shell of the upper port stub is carried out. After phased array ultrasonic nondestructive testing and laser tracker measurement, the weld quality is excellent, and contour accuracy has reached the technical requirements. This study provides important support for the engineering design and construction of the CFETR.

Optimization of Argon Gas Metal Arc Welding Process Parameters with Regard to Tensile Strength for AISI 310 Stainless Steel Using Taguchi Technique

Gas metal arc welding (GMAW) is the leading process in the development of arc welding process for higher productivity and quality. In this study, the effect of process parameters of argon gas welding on the strength of T type welded joint of AISI 310 stainless steel is analyzed. The Taguchi technique is used to develop the experimental matrix and tensile strength of the welded joint is measured using experimental method and finite element method. Optimization of input parameter is performed for the maximum tensile strength of welded joint using ANOVA. The results showed that welding speed is the most significant factor affecting the tensile strength followed by voltage in argon gas metal arc welding (AGMAW) process. Argon gas welding process performance with regard to the tensile strength is optimized at voltage: 18.5 V, wire feed speed: 63 m/min and welding speed: 0.36 m/min.

Emission of scattered radiation from the process zone of welding processes using high-power diode lasers

Highly efficient manufacturing processes in which innovative technologies are continuously integrated are essential for a globally competitive European maritime industry. Promising optimization potential lies in the welding of thick sheet metal. The use of new high-power diode lasers with output powers of up to 60 kilowatts can replace conventional welding processes and significantly improve welding quality and efficiency. In addition to the welding process development with extremely high laser powers, ensuring laser safety is a major challenge for adequate employees’ protection. This work aims to investigate the spatial distribution of laser radiation backscattered from the laser process zone into the hemisphere above the sheet metal. The results of the scattered radiation measurements performed are used to estimate the amount of thermal energy introduced from the laser process zone into a possible protective shielding against the scattered radiation. The derived maximum temperatures finally allow a suitable dimensioning of the shielding.

Research Situation of Welding Performance for P92 Heat Resistant Steel

In this paper, the welding performance of P92 ferritic heat resistant steel in recent years was introduced. P92 steel was a ferritic/martensitic steel, which had been brought to commercial maturity during the last decade due to its excellent high temperature performances. However, the welding related problems of P92 steel was gradually exposed with the wide application, causing a serious impact on the production and operation of boiler unit. Therefore, Strengthening research and development of suitable welding process and post weld heat treatment process that can lead P92 heat-resistant steel to being better serve in the power industry for our country will be the focus of metal workers in the next step.

Possibilities to Apply Friction Stir Processing FSP in Surface Engineering

The results obtained by ISIM Timisoara to the development of the friction stir welding process (FSW) have supported the extension of the researches on some derived processes, including friction stir processing (FSP). The experimental programs (the researches) were developed within complex research projects, aspects regarding the principle of the process, modalities and techniques of application, experiments for specific applications, being approached. The paper presents good results obtained by friction stir processing of cast aluminum alloys and copper alloys. The optimal process conditions, optimal characteristics of the processing tools were defined. The complex characterization of the processed areas was done, the advantages of the process applying being presented, especially for the cast aluminum alloys: EN AW 4047, EN AW 5083 and EN AW 7021. The characteristics of the processed areas are compared with those of the base materials. The results obtained are a solid basis for substantiating of some specific industrial applications, especially in the automotive, aeronautical / aerospace fields.

Manufacturing of molten salt reactor heat exchangers using inner hole welding

ABSTRACT Inner hole welding was applied to weld UNS N10003 nickel-based alloy tubes (φ13.72*1.65 mm) to heat exchanger tubesheet in the Thorium Molten Salt Reactor for the first time. Welding defects were eliminated after the welding technology optimization after a great deal of trials and errors. And proper inner hole welding procedure and good butt joints were obtained. Welding procedure qualification shows that the strength of the welded joints at room temperature, 650°C and 700°C was higher than the qualified values of the base metal. After the confirmation of exact welding conditions on full-size mockup, the first batch of two heat exchangers of Thorium Molten Salt Reactor was fabricated by using inner hole welding technics in the world. The tube bundles containing 58 tubes (116 joints) were welded to tubesheet successfully. Penetration and radiation inspection revealed all the welds had no defects and were 100% qualified. Finally the completed unit passed 0.85 MPa hydrostatic testing. The successful development and application of inner hole welding process also establish a good foundation for the manufacture of high-temperature heat exchangers of other reactors besides Molten Salt Reactor.

Development and Analysis of Ultrasonic Welding Process Using FEM Approach for Aluminum and Copper

Ultrasonic welding is a process that uses mechanical vibrations using ultrasonic frequencies. The vibrations are produced by an ultrasonic sonotrode, which is used for joining two thin materials, especially in electronic industries (for applications in battery-making industries). Typically, ultrasonic welding is based on the parameters (frequency range, input pressure/load of the sonotrode, by varying the coefficient of friction between two metal sheets, the thickness of a sheet) while performing the joining process. In this work, the FEA Model-based study is used for analyzing the ultrasonic welding using “Von-Misses stress theory concepts”. The effects of various thickness of the sheet, normal force, coefficient of friction (at different welding conditions) are analyzed while performing the welding process. The temperature variation is studied while using aluminum and copper as thin sheets. This study can be used in the electronic industries for high power ultrasonic welding process, especially using aluminum and copper materials in the form of electrodes, sheets.

The History of Development of Gas Metal Arc Welding Process

The History of Development of Gas Metal Arc Welding Process

Development in plasma arc welding process: A review

Plasma arc welding process has found wide application for joining of metals in manufacturing industries in the recent times. It has become the preferable welding process over other arc welding processes since it possesses increased welding speed, produces better weld quality, and has less impact of process variability on the process performance. A lot of advancement has taken place to enhance the stability of the plasma arc welding process, increase the depth of penetration and weld quality in recent years. The process is more preferred for welding of similar materials owing to the formation of stable, controlled, and constricted arc with low current requirements. It gives longer electrode life for high production. Variable polarity plasma arc welding (VPPAW) process, Pulsed plasma gas welding (PPGW), Double pulsed plasma arc welding (DPPAW) processes are widely used for joining the mid-thick steels (9.5 mm–12.5 mm). Pulsed plasma gas welding process helps to improve the process stability and the weld quality than other VPPAW process. Apart from these process Laser assisted Plasma arc welding, PAW-MIG hybrid welding, plasma spot welding, soft plasma arc welding process are some of the advancements to the PAW processes which are used for special industrial application. The present review paper focuses on the evolution and the development of the plasma arc welding process, its types, and the suitability of the process towards various applications in the manufacturing industries.

Restraining method for delta ferrite in 9Cr-RAFM welded joint

Abstract Reduced activation ferritic/martensitic (RAFM) steels are important candidates for the first wall and blanket structure in future ADS and fission and fusion energy system. The development of welding process for fusion-centered applications is critical when evaluating the applicability of RAFM steels as structural materials for fusion pressure equipment. Delta ferrite is likely to emerge after welding owing to no nickel addition in RAFM steels, therefore, deteriorates service ability of welding structure. Restraining delta ferrite formation during welding process effectively is a key scientific and technical problem. The aim of this project is to obtain the 9Cr-RAFM steel welded joint with no delta ferrite in them. Research shows that 9Cr-RAFM welded joint can be obtained by friction stir welding without delta ferrite. The 9Cr-RAFM welded joint achieves equal matching to the base metal when the sample is just in the as welded condition. The appearance of onion rings is owing to the tungsten segregation at the interlayer. This study provides new ways to obtain the reduced activation martensite steel welded joint without delta ferrite, and also lays a theoretical foundation for the RAFM steel and the temperature controlled friction stir welding.

Development of a novel arc welding process for obtaining beautiful wave-shaped weld bead

Development of a novel arc welding process for obtaining beautiful wave-shaped weld bead

高能率・高品質エレクトロスラグ溶接法の開発（第2報）

高能率・高品質エレクトロスラグ溶接法の開発（第2報）

Development of novel MIG welding process with duplex current feeding

MIG welding under pure argon shielding gas atmosphere (pure argon MIGW) is suitable to obtain a high-strength and high toughness welded joint. However, pure argon MIGW is difficult to be applied practically to welding structure because of arc instability as well as low wettability and shallow penetration of weld bead. For solving the above problems, a novel MIG welding process with a duplex current feeding (DCF-MIGW) has been developed. The DCF-MIGW enables to control the wire feeding speed and the welding current independently by additionally feeding secondary current near the wire tip. In this paper, the basic characteristics of DCF-MIGW were clarified. As a result, under the same wire feeding speed, the DCF-MIGW was able to feed larger welding current than that of the conventional MIG welding. Accordingly, the quantity of heat of droplets in the DCF-MIGW was found to increase with the increase in the secondary current, leading to improved wettability and deeper penetration. The increased welding current also contributed to the arc stability. The multi-layer welding using the DCF-MIGW enabled to avoid the weld defects to prove the practical effectiveness of the DCF-MIGW.

Refill friction stir spot welding of surface-treated aerospace aluminum alloys with faying-surface sealant

Refill friction stir spot welding (RFSSW) is a derivative of friction stir spot welding (FSSW). Unlike conventional FSSW, it does not leave behind an exit hole in the workpiece. Kawasaki Heavy Industries (KHI) developed a novel robotic RFSSW system for aerospace applications. To date, researchers documented numerous studies on refill friction stir spot welding of bare aerospace aluminum alloys. This study explores further and demonstrates refill friction stir spot welding of surface-treated dissimilar aluminum alloys with a faying-surface sealant. Surface treatments are vital for corrosion inhibition and paint adhesion of aircraft structures. An ability to join metals with surface treatments is an enabler in implementing the RFSSW technology in aerospace applications. The presented study features the welding process development, mechanical tests, and comparisons between bare and surface-treated RFSSW coupons.

高能率・高品質エレクトロスラグ溶接法の開発（第1報）

高能率・高品質エレクトロスラグ溶接法の開発（第1報）

Investigation and development of friction stir welding process for unreinforced polyphenylene sulfide and reinforced polyetheretherketone

The joining of thermoplastics through welding offers numerous advantages over mechanical joining. Most importantly, it eliminates the use of costly fasteners and has only a limited effect on the strength of the parts being joined. Since it does not require the introduction of holes, loading pins, and the associated stress concentrations, a specific form of welding, friction stir welding (FSW), was investigated for the creation of butt joints of unreinforced polyphenylene sulfide (PPS) and short carbon fiber (CF)-reinforced polyetheretherketone (PEEK) plates. Unlike metals, analytical models and experimental results show that the heat generated by the FSW tool is insufficient to produce the heat required to weld thermoplastic materials. Therefore, a second heat source is required for preheating these thermoplastics. In this research, a resistance type surface heater was placed at the bottom of two identical weld pieces to produce good quality welds. Two types of shoulder design such as rotating shoulder and stationary shoulder were developed in this study. Taguchi’s design of experiment method was utilized to develop the welding process, where heating duration, material temperature, tool rotational speed, and tool traverse speed were used as the welding parameters. One of the process parameters, tool traverse speed, had significant influence on the tensile strength of PPS samples. While PPS sample showed relatively lower tensile strength with higher traverse speed, short CF-reinforced PEEK samples had higher tensile strength with a higher traverse speed. In addition to tensile tests, fracture toughness tests were performed for both PPS and PEEK samples to observe the influence of unwelded segments in the welded parts. In this study, joint efficiency of PEEK samples was found to be higher than that of PPS samples. Micrographs of PEEK samples showed uniform homogenous mixture of part materials.

Investigations on laser welding of dissimilar joints of steel and aluminum using a high-power diode laser

Lightweight construction is currently of high interest, not only for the automotive sector, but also for the maritime industry, due to various benefits. On the one hand, CO2 emissions can be reduced as a result of lower fuel consumption, and on the other hand a higher speed can be achieved, especially for yachts. Hence, hybrid joints of steel and aluminum parts are in great demand for yachts. Presently, these parts are joined using explosive welding adapters, which are complex, time-consuming, and costly to manufacture. For efficient manufacturing of such adapters, a high-power laser welding process is predestined. Aluminum alloy EN AW-6082 (t = 8 mm) and steel S355 (t = 5 mm) are welded in a lap joint configuration using a diode laser with a laser beam power of 10.4 kW. The challenge of welding this dissimilar material combination is the formation of hard and brittle intermetallic compounds within the weld seam, which may lead to cracks and negative effects on mechanical properties of the joint. To meet the required mechanical properties, the mixing ratio of the intermetallic compounds can be limited, as determined in the context of the presented welding process development. Using suitable mixing ratios, the weld seam quality can be increased as shown in metallography analysis, hardness tests, and tensile shear tests. Among other things, the welded samples provide a shear force of approximately 9 kN.

Characterization of weld attributes in ultrasonic welding of short carbon fiber reinforced thermoplastic composites

Ultrasonic welding is a well-known technique for joining thermoplastics and has recently been introduced for joining carbon fiber reinforced thermoplastic composites. However, there is a lack of understanding on how weld quality attributes develop under different welding conditions, especially without using an energy director. In this paper, ultrasonic welding of an injection molded short carbon fiber reinforced composite is tested to investigate three important weld attributes, bonding efficiency, weld area, and horn indentation. From a two-level full factorial experiment, welding energy is found having the most important influence on joint quality, which is related to weld attributes. Thus, only welding energy is varied to simplify the analysis of weld attributes evolution during the welding process. After examining the microstructure of the cross sections and the fracture surface of the welded joints, several observations were obtained. First, the bonding formation for the carbon fiber reinforced composite is mainly through the polymer–polymer interface healing with involved carbon fibers as reinforcements. Second, the bonding efficiency and weld area increase with an increase in welding energy until they reach a threshold. As welding energy continues to increase, the bonding efficiency will decrease due to material degradation as pores develop, but weld area will remain unchanged. Finally, the difference of welding attributes leads to three failure modes of the joints, e.g. interfacial separation, nugget shear fracture, and nugget pull-out fracture, which are an indicator of the joint quality. These experimental observations provide insights toward the development of a robust ultrasonic welding process for fiber reinforced composites.