Analiza materijala elektroda za elektrootporno točkasto zavarivanje

The contribution deals with metallographic analysis of welding tip materials and workpieces used in production. Microstructures of most used alloys Cu for welding electrodes of resistance spot welding are evaluated. Alloys of CuCr1Zr, CuCoBe and CuBe2. Analysis of influence of alloying elements and production technology of the alloys on final properties of electrode materials are presented.Ovaj rad se bavi metalografskom analizom materijala elektroda za elektrootporno točkasto zavarivanje koji se koriste u proizvodnji. Mikrostrukture najčešće korištenih legura Cu za izradu otpornih elektroda za točkasto zavarivanje su evaluirane. Analizirane su legure: CuCr1Zr, CuCoBe i CuBe2. Analiza utjecaja legirajućih elemenata i tehnologije proizvodnje legura na konačna svojstva materijala elektroda je također predstavljena u radu

DEFORMATION INFLUENCE ON A LIFETIME OF WELDING ELECTRODE TIPS

The contribution deals with the influence of welding electrode tips deformation on their lifetime. The influence of material properties, production technology and the intensity of welding electrodes load on their lifetime are presented. The electrode tips of the most used type of CuCr1Zr alloy of three basic standard shapes before and after the process of welding are evaluated. The process of welding is realized with low, middle and maximum welding parameters on programmable pneumatic spot welding machine VTS BPK 20. The influence of welding parameters on chosen material characteristics of welding tips is observed. Through the use of upsetting test, dependency of forming strength and deformation of material on used technology of welding tip production is observed

POSSIBILITIES OF RENOVATION FUNCTIONAL SURFACES OF EQUIPMENTS IN THE MECHANICAL ENGINEERING INDUSTRY

The paper analyzes the possibilities of increasing the lifespan of rollers in continuous steel casting line. There are analyzed the causes of the surface rollers damage and the impact of degrading factors in metallurgical production. Three types of welding consumable electrodes designed for restoration layers formation applied by SAW surfacing technology were analyzed. There were analyzed microstructure, microhardness and properties of weld clads in tribological conditions

Influence of welding current in resistance spot welding on the properties of Zn coated steel DX51D

The paper deals with the resistance spot welding of three galvanized car body sheets DX51D + Z - EN 10142/2000. The quality of welded joints was evaluated by destructive tests and non-destructive tests. For evaluation of joints quality the shear tension test on spot joints according to DIN 50 124 standard was used. The influence of welding parameters on the structure of a welded joint was observed by metallographic analysis. Influence of welding current from 6.0 to 7.7 kA and influence of welding time from 10 to 12 periods on weld properties was observed. Increasing the welding current led to increased load-bearing capacity of the welded joints. The spot welded joints without any internal defects occurred in samples welded up to 7.0 kA. Increasing the welding time to 12 periods led to increased load-bearing capacity of the welded joints, within all observed values of welding current

Optimization of resistance spot welding parameters for microalloyed steel sheets

The paper presents the results of resistance spot welding of hot-dip galvanized microalloyed steel sheets used in car body production. The spot welds were made with various welding currents and welding time values, but with a constant pressing force of welding electrodes. The welding current and welding time are the dominant characteristics in spot welding that affect the quality of spot welds, as well as their dimensions and load-bearing capacity. The load-bearing capacity of welded joints was evaluated by tensile test according to STN 05 1122 standard and dimensions and inner defects were evaluated by metallographic analysis by light optical microscope. Thewelding parameters of investigated microalloyed steel sheets were optimized for resistance spot welding on the pneumatic welding machine BPK 20

Innovation of Biomass Crusher by Application of Hardfacing Layers

This paper presents the innovation possibilities of the crushers functional parts and the results of layers’ renovation analyses of the surfaces worn by biomass crusher hammers. The worn functional surfaces of hammers made of Hardox 400 material were renovated by manual arc welding method (welded with a filled wire electrode with its own protection). As an additive material, Lincore 60-O tubular wire from Lincoln Electric was used. The quality of weld layers was assessed on the metallographic sections, where the presence of internal defects was monitored, and the microstructures of welds were identified. In addition to the metallographic analysis, the microhardness in terms of EN ISO 9015-2 was assessed. Based on the performed experiments, it is suitable for the crusher innovation to recommend the chain replacement with a shaped weldment made of Hardox 400 material, the weldability of which is very good, and to make at least one hardfacing layer on its functional surfaces. With this innovation, the service life of the crushing segment could be extended by more than ten-fold

Influence of the Hardfacing Welds Structure on Their Wear Resistance

The contribution presents the research results of hardfacing metals’ resistance in conditions of abrasive wear. Two types of hardfacing electrodes with a different chemical composition were used in the creation of three layers of hardfacing metals. The chemical composition of electrodes determines the difference in a hardface deposit structure. We have investigated the influence of mixing the base metal and a filler metal and the influence of hardfacing welds structure on the resistance against abrasive wear. The results of the experiments have showed that the intensity of wear is very dependent on the parameters of wear as well as the morphology structure of hardfacing metals

Steel Surface Defect Classification Using Deep Residual Neural Network

An automated method for detecting and classifying three classes of surface defects in rolled metal has been developed, which allows for conducting defectoscopy with specified parameters of efficiency and speed. The possibility of using the residual neural networks for classifying defects has been investigated. The classifier based on the ResNet50 neural network is accepted as a basis. The model allows classifying images of flat surfaces with damage of three classes with the general accuracy of 96.91% based on the test data. The use of ResNet50 is shown to provide excellent recognition, high speed, and accuracy, which makes it an effective tool for detecting defects on metal surfaces