Effect of Ultrasonic Techniques on Welding Technologies

The article discusses selected physical properties of industrial ultrasonic equipment utilising the magnetostrictive or electrostrictive effect. Particular attention was paid to equipment enabling the ultrasonic welding of various metals and thermoplastics. The research involved the comparison of various designs and operation of technological equipment, taking into account selected energy, control and environmental aspects. Based on reference publications it was possible to determine and categorise general features concerning the application of ultrasonic technologies as well as to indicate factors responsible for the formation of imperfections during the ultrasonic welding process.

High-Speed Friction Welding as an Innovative Technology for Joining Solenoid Valve Elements Made of Steel Grades 11SMnPb37 and 11SMn37

High-speed friction welding (HSFW) is a solid-state joining process involving the use of friction heat emitted during the technological process. The application of the HSFW technology enables the fast and repeatable making of joints characterised by favourable properties. The article presents tests concernin the development of the HSFW-based technology enabling the joining of solenoid valve elements made of two grades of free-cutting steel, i.e. 11SMnPb37 and 11SMn37. The article also discusses the course of technological tests, the making of a test rig, the determination of ranges of technological parameters and selected test results concerning welded joints.

Friction Stir Welding of Wrought Aluminium Alloy EN AW- 6082

The article presents results of the friction stir welding of 6 mm thick plates made of wrought aluminium alloy EN AW-6082. Tests discussed in the article involved the identification of the effect of primary welding process parameters on the quality of welds. Test welds were subjected to visual tests, measurements of temperature (inside the weld), tensile strength tests as well as macro and microscopic metallographic tests and structural tests (performed using a scanning electron microscope). The application of the appropriate values of the primary welding process parameters (i.e. the tool rotation rate and the welding rate) enabled the obtainment of the high and repeatable quality of FSW joints made of aluminium alloy EN AW-6082. The test results presented in the article can offer technological solutions for potential

Hybrid Welding of Metal-Polymer Composites with a Non- Conducting Polymer Layer

Metal-polymer composites (MPCs) are becoming increasingly popular primarily because of their high strength-to-weight ratio. Metal-polymer composites consist of three layers, i.e. two external metallic sheets (linings) and the core made of plastic. The presence of the internal plastic layer makes MPCs impossible to join using conventional welding processes, which significantly limits their usability. One of the solutions to the problem involves the use of hybrid methods, e.g. ultrasonic method-aided resistance welding. The research work discussed in the article involved the development of a prototype test rig and a technology enabling the joining of the Litecor® composite with steel DP600. The joining process consisted of two stages. The first stage involved the removal of the non-conducting layer of polymer from the welding area and the making of an appropriate electric contact for resistance welding. The second stage was the classical resistance spot welding process. The development of the concept posed a challenge as it was necessary to develop an appropriate acoustic waveguide for high-power ultrasonic waves which, at the same time, could transfer loads in the form of electrode force as well as provide appropriate electric and thermal conductivity without compromising acoustic parameters during the welding process. The development of the test rig was followed by the performance of numerous tests aimed to identify the appropriate window of process parameters. Test joints were subjected to macrographic, strength, ultrasonic and topographic tests.

Selected Aspects of the FEM-Based Numerical Modelling of Current Propagation in the Resistance Multispot Cruciform Welding of Bars

The article presents selected aspects of the FEM-based analysis concerning resistance welding processes performed using multispot welding systems. The analysis was based on a three-spot welding machine used for the joining bars in the cruciform configuration. Both two and three-dimensional modelling was performed as the comparative analysis of two computing software packages, i.e. the commercial ANSYS Mechanical software package and the ARTAP software package, available on an open access basis. The research work involved the determination of current propagation in various welding process configurations as well as the identification of the percentage loss of welding current and power resulting from the bridging of current by neighbouring welds. The article discusses the effect of the method of the power supply and the earthing of the system of electrodes along with the welded material on the manner of current propagation. The analyses presented in the article were performed in relation to the DC power supply (inverter welding machine). Related calculations were performed using averaged (in terms of heat and resistance) material parameters.

New Weldable Steel for Rebars

A new steel grade, developed at the CELSA steelworks in Ostrowiec Świętokrzyski and used in the production of rebars, contributes greatly to the development of industrial and civil engineering. Steel B600B is characterised by yield point fyk = 600 MPa and immediate tensile strength ftk = 700 MPa. Tests revealed that the steel satisfies all requirements of related standards, both in terms of strength and processing properties. The mechanical properties of the new steel grade are higher by 20% than those of currently produced steels characterised by the highest mechanical properties (characteristic yield point Re= 500 MPa). As a result, the application of the new steel provides notable technical and economic advantages. The new steel grade meets requirements concerning technical class C in accordance with PN-EN 1992-1-1, which indicates that the steel has a significant yield point margin (being an important advantage in terms of limit state design). Plastic steels are easier to weld and less susceptible to welding crack formation. Technological (research-related) tests revealed the favourable welding properties of the new steel. Welding tests were performed using the manual metal arc welding method, i.e. the most common welding process used when making structural reinforcements. The welding tests involved the making of butt, overlap and cruciform joints. The strength and technological tests revealed that the steel satisfied the requirements specified in the PN-EN ISO 17660-1 standard.

Electron Beam Melting of Thermally Sprayed Layers – Overview

Thermal spraying is one of the most common methods enabling the deposition of variously-purposed layers on surfaces of structural elements. However, in certain cases, the process of spraying itself is ineffective in terms of the stability and properties of protective layers. One of the possible solutions making it possible to reduce the porosity and improve the adhesion of surfaced layers involves their melting using the concentrated electron beam. The article contains an overview of reference publications concerning electron beam melting technologies.

Unconventional Methods of Non-Destructive Tests. Part 3.

The article presents some testing methods applicable in the aviation industry. In addition to popular non-destructive methods, NDT methods used in the aviation industry (and discussed in the article) include optical holography or shearography. Structural materials used in the aviation industry as well as the importance of analyses, both at the manufacturing stage and during operation, require the performance of regular tests as a negligent approach to such activities could end up in a catastrophe.

High-Performance Methods for Welding Steel P460NL2

The article discusses comparative test results concerning two welding methods, i.e. SAW and MAG. The tests involved the making of welded joints in steel P460NL2, the verification of the chemical composition of supplied steel, the comparison of the quality of joints (in accordance with PN-EN ISO 5817) as well as the performance of macroscopic tests and the comparison of mechanical properties and hardness.

Selected Properties of High-Frequency Electric Arc Initiators and Stabilisation Oscillators. Part 2. Devices with Compressed Electric Arc

The second part of the overview article discusses general features of the design and operation of selected industrial arc plasma torches. Because of their structural and operating differences, plasma torch power supply systems with internal and partly external arc are discussed separately. Particular attention was paid to the design of electric systems used for the initiation of arc discharges. Because of the fact that the operation of plasma torches with partly external arc is often accompanied by the formation of double arc, the article also presents measures and methods enabling the prevention of the aforesaid unfavourable phenomenon. In addition, the article discusses selected technological properties of plasma torches and micro-plasma torches used for joining, cutting, surfacing and hardening.