Field Of Welding Technology Research Articles

Optimizing Advanced High‐Strength Steel Joints via Regional Rapid Cooling in Resistance Spot Welding

During resistance spot welding (RSW), the thermal cycles that occur cause microstructural differentiations in the heat‐affected zones of martensitic steels, leading to internal stresses. In this context, a new and innovative methodology has been developed to minimize the adverse effects of heterogeneous hardness changes in the welding area on joint durability. This methodology utilizes a unique prototype setup based on the regional rapid cooling (RRC) process, which is integrated into the welding machine and operates in synchronization with the machine during the process. Through this setup, the aim is to effectively control the microstructure and hardness values in the welding area. This innovative approach presents potential improvements in the field of welding technology by aiming to optimize material performance during the welding process. According to microstructure results, the RRC process has narrowed the heat‐affected zone to 1.27 mm, increased the hardness values by 9.2%, showed a 3% increase in tensile‐shear strength, a 9% increase in cross‐tension strength, and based on fatigue strength results, no fractures occurred in all specimens subjected to a force of 0.3 kN.

Samarbetet mellan TNC och RTT 1938–1998: Terminologiarbete som resurs för meningsfull kommunikation

This article describes and analyses the contacts between the Swedish and Norwegian national terminology organisations between the 1940s and the 1990s. The Swedish Tekniska nomenklaturcentralen TNC (1941–2018; 2000–2018 Terminologicentrum TNC) was Sweden’s national center for special languages and terminology work for more than 75 years. Since its founding in 1941, the TNC was active not only in Sweden, but also in establishing and maintaining international contacts. The Norwegian Rådet for teknisk terminologi RTT was founded in 1938 and closed down in 2001. The research material used is the collection of correspondence in the TNC’s document archive, in particular the section stored with the code “Unor”, i.e., letters (N=374) documenting written communication between the TNC and the RTT. The article describes the topics covered in the communication, the individuals involved, the objectives and consequences of the communication and the results achieved. In a quantitative analysis, the themes of the letters are categorised in four main categories: publications, communication, information, and language issues. In a qualitative analysis, a specific terminological issue in the field of welding technology is analysed by close reading and content analysis. Finally, further studies, which complete the picture of terminological cooperation on institutional level in the Nordic countries, are proposed.

A hybrid machine learning model for predicting continuous cooling transformation diagrams in welding heat-affected zone of low alloy steels

Continuous cooling transformation diagrams in synthetic weld heat-affected zone (SH-CCT diagrams) show the phase transition temperature and hardness at different cooling rates, which is an important basis for formulating the welding process or predicting the performance of welding heat-affected zone. However, the experimental determination of SH-CCT diagrams is a time-consuming and costly process, which does not conform to the development trend of new materials. In addition, the prediction of SH-CCT diagrams using metallurgical models remains a challenge due to the complexity of alloying elements and welding processes. So, in this study, a hybrid machine learning model consisting of multilayer perceptron classifier, k-Nearest Neighbors and random forest is established to predict the phase transformation temperature and hardness of low alloy steel using chemical composition and cooling rate. Then the SH-CCT diagrams of 6 kinds of steels are calculated by the hybrid machine learning model. The results show that the accuracy of the classification model is up to 100%, the predicted values of the regression models are in good agreement with the experimental results, with high correlation coefficient and low error value. Moreover, the mathematical expressions of hardness in welding heat-affected zone of low alloy steel are calculated by symbolic regression, which can quantitatively express the relationship between alloy composition, cooling time and hardness. This study demonstrates the great potential of the material informatics in the field of welding technology.

Applications of Molten Pool Visual Sensing and Machine Learning in Welding Quality Monitoring

On-line monitoring of welding quality is very important to the realization of intelligent welding technology and has become a research hotspot in the field of welding technology. This article reviews the research results and latest research progress of welding quality on-line monitoring based on molten pool visual sensing in recent years. First, it introduces the characterization of welding quality by the two-dimensional geometric features and three-dimensional topographic features of the molten pool in detail, and then analyzes the application of machine learning and feature engineering in the online prediction of welding status; we discuss the deep neural network and welding quality at the end Convergence of online detection technology. The work done in this paper reviews the progress of online monitoring technology for welding quality and provides a basis for the follow-up work.

Investigation of Mechanical Properties in Welding of Shape Memory Alloys

Shape-memory alloys (SMA) are increasingly used due to the exceptional properties such as shape memory effect (SME), Pseudo elasticity and super-elastic effect (SE). However, mechanical properties of SMA are scantly studied in the field of welding technology. In this study, effect of laser welding on SMA is considered through investigation of mechanical properties as well as microstructure of the weldments. The specimens have been manufactured from NiTi, one of the most popular SMA alloys in the industry, in order to evaluate tensile strength and microstructure before and after the laser welding process. Based on the results, higher ultimate tensile strength and elongation are achieved in the specimens for which the tensile test was carried out in same direction as manufacturing rolling direction. Furthermore, microstructure investigations show that the behavior of solidification is changed from planar to volumetric and/or to dendritic. Due to this evolution, the joint tensile strength and strain reached to 118MPa and 8%, respectively.

The Influence of Modelling Material Zones on Strains and Stresses at Weld Toe Notch

The latest development in the field of welding technology enabled prefabrication of thinwalled sandwich structures in an industrial scale. Sandwich structures fabricated of steel, or aluminium alloy plates and stiffeners are welded with the use of hipower CO2 lasers. Strength analysis of such structures with the use of finite element method needs proper material modelling. In this paper the material model of steel sandwich panel tee-joint is analysed. The influence of including different material zones on strains and stresses at the weld notch area is presented. The analysis shows that material changes outside the weld notch area do not influence the results of strains and stresses. The impact of the geometrical notch is very local and it does not interfere with material property changes at neighbouring weld zones. For the purpose of determination of maximum values of stresses and strains at weld toe notch, the analysed laser weld can be modelled with the use of one material property for all weld zones.

Laser Beam Structured Sheets – A New Potential for Sheet Metal Forming

The increasing requirements of car body manufacturers concerning formability and load of sheet metal structures necessitate new approaches in forming technology. Especially the requirements as regards local loads and local forming behaviour of the components vary significantly. In the field of welding technology there is a verified effect of emerging higher strengths in the welding seam. Using a laser, similar effects can be applied to change the material properties locally. In the current investigation the use of a laser beam allows for creating very small heat-affected areas of a width from 0.5 mm up to 5 mm. These areas are characterised by a significantly higher hardness and strength. Depending on the sheet metal material, areas of higher and lower hardness can be produced. Using laser heat-affected zones in sheet metal makes it possible to increase the drawing depth without necking or cracks. The heat-affected zones increased the stiffness in the critical necking area and hence moved the critical strains to the surrounding area. The required formability was guaranteed by the adjacent areas and the draw depth can be increased.

Application of Computer and Network Technology in Welding Power Source Design

Welding power source is an important research content in the field of welding technology. It is of significance to organize the design database of welding power source, develop its interactive website and construct its remote management platform based on web. In the scope of this paper, the core technology applied in above aspects were analyzed and summarized, the current development status and future trend of the application of computer and internet technology in welding power source areas were introduced.

Suitability of Friction Welding of Tube to Tube Plate Using an External Tool Process for Different Tube Diameters-A Study

During the past few decades, the field of welding technology has been witnessing tremendous challenges. Welding is an important metal fabrication process that has high potential for industrial applications. Friction welding is a vital solid state joining process that has gained popularity in welding non-weldable alloys. Friction welding of tube to tube plate using an external tool (FWTPET) is an innovative friction welding process and it was invented in the year 2006. FWTPET is capable of welding tube to tube plate of similar or dissimilar metals and is capable of producing good-quality leak-proof weld joints. In this work, four different tube diameter conditions in FWTPET welding have been studied. Macrostructural and microstructural studies have been conducted and they reveal the weld configuration that is susceptible to defect formation. Hardness and tensile strength of four different tube diameter preparations have been analyzed. The present study leads to the production of defect-free weld joints which have numerous industrial applications.

Computer and Network Oriented Welding Power Source Design

Welding power source is an important research content in the field of welding technology. It is of significance to organize the design database of welding power source, construct its development platform, and realize its CAD and simulation system based on Web. In the scope of this paper, the core technology applied in above aspects were analyzed and summarized, the current development status and future trend of the application of computer and internet technology in welding power source areas were introduced.

The innovative use of low heat input in welding: experiences on ‘cladding’ and brazing using the CMT processPaper presented at the 4th National Welding Day, Workshop: “Brazing”, Genoa, 25–26 October 2007.

As is well known in the field of welding technology, the heat input in a joining process is a defining factor of the results that can be obtained in numerous aspects directly affecting metallurgical phenomena, technological properties and the integrity of the welded joint, as well as deformations and residual stresses. Furthermore, a different heat input can be decisive on process productivity and economy. This article concerns tests conducted in the IIS Special Welding Process laboratory with the collaboration of Arroweld Italia pertaining to two technological subjects of considerable interest, such as ‘cladding’ with high corrosion resistance alloys and thin layer brazing, both using continuous wire welding methods with gas shielding, in an entirely particular version known as ‘Cold Metal Transfer – CMT®’. In the case of ‘cladding’, the most critical aspects of anticorrosion overlay, such as penetration into the substrate and level of dilution, which frequently compromise the intrinsic corrosion resistance of the coating, are investigated. On the other hand, with regard to brazing, the degree of deformability of brazed structures is investigated, as well as the impact of the process on the mechanical properties of the base material and any influence, or otherwise, of the presence of galvanizing layers on brazed joint quality (bonding, spraying, etc.).