This paper presents the results of a study on the development of a Metal active gas (MAG) welding technology for an industrial furnace component made of steel S235JRC+N with respect to the minimizationof welding deformation. A numerical simulation of the welding process was performed in the first phase of the research. The numerical simulation was carried out with the SYSWELD software. For the numerical simulation of the welding process, the FEM method was used. In the simulation, four variants of restraint of the industrial furnace wall panel elements during the execution of the welding process were investigated. They differed in the number of restraints (model 1–4). It was found that the difference between the maximum mean strain in model 1 and the lowest mean strain in model 4 was only 11%. A physical simulation of the welding process was then performed with a restraint variant according to model 1. The displacement results obtained from the physical simulation of the welding process were compared with the displacement results from the numerical simulation. Discrepancies between numerical and physical simulation displacement values were found. The quality of selected welded joints was also evaluated. Visual testing (VT) and measurements of weld geometries were performed for this purpose. Metallographic tests and hardness measurements were performed to determine of influence of the welding process on the microstructure of the welded joint area, especially the heat affected zone (HAZ). The results obtained confirm the correctness of the assumptions made regarding the technology of manufacturing the furnace wall panels.

This paper presents the results of structural tests and hardness measurements of rebuilding coatings manually applied by the gas tungsten arc welding (GTAW) method on damaged surfaces of steel shafts of turbochargers of automotive engines. Single- and double-layer coatings were applied in an argon atmosphere by fusing a 1.2 mm diameter wire with a Fluxofil M58 flux core, using a current of 35A and an arc voltage of 8–9 V. The hardfacing resulted in coatings with a martensitic–bainitic structure with fine dispersed carbides rich in M23C6-type chromium. The hardness of the coatings on the rebuilt shafts averaged from about 740HV5 for the single-layer coating to about 770HV5 for the double-layer coating and was two times higher than the hardness of the tempered shafts without coatings.

The article presents results of Sysweld software programme-based tests involving the use of numerical simulation in the improvement of the welding of a storage tank head with respect to the minimisation of welding strains (distortions). The development of CAD models and mock-ups used in the FEM analysis was based on drawing documentation. The numerical simulation concerning the distribution of the field of displacements in the storage tank head was performed for four models, involving various welding sequences and directions. Related analyses involved the initial model applied in the technology currently used in the fabrication of storage tank heads as well as three new models (of welding sequences and directions). The comparative analysis, involving the initial model and the three new models, was concerned with different values of displacements in all directions (X, Y and Z) and at all characteristic points of the storage tank head. The simulation results revealed the existence of correlations between welding sequence and directions and varied distributions of fields of displacements (strains/distortions). Post-weld distributions of fields of displacements in the initial model and models 2-4 were characterised by varied values of displacements, yet also by the similar nature of tank head stress-triggered distortions. Dimensionally relevant displacements (distortions) of the storage tank head were observed in direction Z (i.e. direction perpendicular to the surface). In all the models subjected to analysis, the greatest displacements were identified in the areas of storage tank head nodes. Selected welding stages in the initial model were characterised by greater displacements than those observed in models 2-4. In line 1, higher values were observed at stages 8-10, 12 and 13. In turn, in line 2, higher values were observed at stages 8-10. In addition, in line 2, stages 11-14 were characterised by greater displacements in the initial model if compared with those identified in models 3 and 4. The FEM-based analysis of the tank head enabled the qualitative verification of tank-related welding schemes in terms of welding strains.

The paper presents the continuation of experimental champagne of tests of bolted end-plate joints under static and impact loading condition. Based on initial observation after previous experimental tests the main focus was directed into bolts behavior. A differ failure modes of 10.9 grade bolts under static and impact loading constituted a need deeper analysis of this phenomenon. A comprehensive test of chemical analysis and mechanical parameters of bolts were conducted. Moreover, on specially prepared microsections the microstructure and microhardness were tested. Microstructural studies revealed a martensitic-austenitic structure with defects in the form of voids and non-metallic inclusions such as titanium nitrides and iron oxides. On originally damaged surfaced of bolt shank under static and impact loading, the fractography was performed. Fractographic observations revealed the initiation of cracks in the thread profile area. The probable cause of the microcracks was the stresses introduced during the technological process of thread formation and hot-dip galvanizing. Under static loading, crack propagation occurred under yielding conditions, leading to fracture at a characteristic angle of approximately 45°, which is typical of a shear mechanism. Meanwhile, under impact loading a sudden fracture was observed near the bolt core, indicating a brittle fracture at a high load rate. The sharp-edged dents and accompanying microcracks created during the technological process of bolt production created conditions for the development of brittle cracks.