This article presents the results of steel-sheet lap-joint-welding using laser beam radiation. The use of a laser beam and keyhole effect for deep material penetration in lap joint welding was presented. Thermodynamic mechanism of laser welding is related to material properties and process parameters. Estimation of welding parameters and joint properties’ analysis was performed through numerical simulation. The article presents a possibility of modeling laser lap-joint welding by using Simufact Welding software based on Marc solver and thermo-mechanical solution. Numerical calculation was performed for surface and conical volumetric heat sources simulating laser absorption and keyhole effect during steel sheet welding. Thermo-mechanical results of fusion zone (FZ), heat-affected zone (HAZ) and phase transformations calculated in numerical simulation were analyzed. The welding parameters for partial sealed joint penetration dedicated for gas piping installations were estimated from the numerical analysis. Low-carbon constructional steel was used for numerical and experimental analyses. A trial joint based on the estimated parameters was prepared by using a CO₂ laser. Numerical and experimental results in the form of hardness distributions and weld geometry were compared. Metallographic analysis of the obtained weld was presented, including crystallographic structures and inclusions in the cross section of the joint.

This paper presents the results of laser welding of dissimilar joints, where low-carbon and stainless steels were welded inthe lap joint configuration. Performed welding of austenitic and ferritic-pearlitic steels included a sealed joint, where only partial penetration of lower material was obtained.The authors presented acomparative study of the joints under different configurations. The welding parameters for the assumed penetration were estimated via anumericalsimulation. Moreover, a stress–strain analysis was performed based on theestablished model. Numerical analysis showed significant differences in joint properties, therefore, further study was conducted. Investigation of the fusion mechanism in the obtained joints wascarried out using electron dispersive spectroscopy (EDS) and metallurgical analysis. The study of the lap joint under different configurations showed considerable dissimilarities in stress–strain distribution and relevant differences in the fusion zone structure. The results showed advantages of using stainless steel as the upper material of a microstructure, and uniform chemical element distribution and stress analysis is considered.

Paper presents results of microstructure and tests of welded joints of new generation VM12-SHC martensitic steel using high power CO₂ laser (LBW method) with bifocal welding head. VM12-SHC is dedicated to energetic installation material, designed to replace currently used. High content of chromium and others alloying elements improve its resistance and strength characteristic. Use of VM12-SHC steel for production of the superheaters, heating chambers and walls in steam boilers resulted in various weldability researches. In article are presented results of destructive and non-destructive tests. For destructive: static bending and Vickers hardness tests, and for non-destructive: VT, RT, UT, micro and macroscopic tests were performed.

This article presents a numerical analysis of laser-welded flange pipe joints. The presented results concern the welding of low carbon S235JR and stainless 316L steels using a CO2 laser in lap and fillet joint configurations. The estimation of welding parameters was achieved using Simufact Welding software and numerical simulation, where output power, feed rate, efficiency and intensity distribution (Gaussian parameter) were analysed. In accordance with the established model, a thermo-mechanical simulation was performed. The calculated joint geometries show good agreement with experiments; therefore, the obtained results were used to study selected joint properties of both joint types. Stress-strain distribution was estimated on the basis of thermomechanical analysis. Weld bead geometry obtained from numerical simulation was compared with the results from trial joints. The numerical model established for both joint configurations shows good agreement with experimental results and were assumed to be accurate. The results of the performed analysis shown some advantages of the use of this configuration of lap joints in flange pipe joints.

This study presents the results of laser beam welding of dissimilar high-alloy super stainless steels. Differences in their thermal and mechanical properties pose significant challenges in manufacturing processes. The present work demonstrates the potential advantages of using 309L filler material in laser welding of high-alloy materials with different properties. The research focuses on a comparative evaluation of the effects of 309L filler metal on the TP904L—TP347 joint in terms of joint strength and microstructure. The analysis of the joints provides insight into the role of the filler metal in improving joint properties. The obtained results show that both welds exhibit a similar microstructure composed of pillar, cellular, and equiaxed dendrites; however, they differ in dendrite growth orientation, calculated ferrite number (FN), the G/R ratio, and dendrite arm spacing, indicating a lower thermal gradient in the joint welded with filler metal. The results also reveal the presence of precipitates in the welds near the TP904L steel fusion line, most likely Cr₂₃C₆ type. Mechanical properties evaluation, based on standard and miniaturized tensile tests as well as hardness measurement, shows that the use of 309L filler metal improves both the joint strength and ductility, although it does not significantly affect the material hardness.

The paper reports the three-point bending test results of welded joints. The joints were made of chromium-molybdenum cast steel designed for the use at elevated temperatures. TIG (tungsten inert gas) welding technique was used. The fracture energy for particular joint zones and the stretch zone width (SZW) under the notch bottom were determined in a qualitative fracture toughness assessment. Fracture surface morphology was analyzed. The stretch zone measurement indicated a qualitative relationship between its width and the values of fracture energy. The results confirmed the influence of the modification on the character of fracture and the portions of brittle and ductile fracture in particular areas of welded joints.