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.
Abstract:The paper attempts to determine the impact of fuel impurities on the spark discharge energy and the wear of the spark plug electrode. Spark plugs were analyzed in two typical configurations of the ignition system. A number of tests were conducted to determine the wear of the spark plug electrode exposed to different types of impurities. The spark discharge energy for new and worn spark plugs was determined through calculation.
The article presents the problem of planning the laser beam trajectory for the laser micromachining process. The article concerns on the ablative laser micromachining issues. Different effects of laser beam trajectory on pocket geometry in laser micromachining were investigated. The results of experimental tests are presented. Based on the research, potential causes of different effects of the laser beam for various trajectories were formulated. Several different types of trajectories for the assumed shape were developed for the purposes of the research. Laser micromachining was performed with fixed parameters of the laser device using different trajectories. The article indicates the significant impact of the laser beam trajectory on the effect of interaction on matter during the laser milling process, which is not often mentioned in scientific reports. The article presents the basic geometrical measurements indicating the need to determine the leading of the laser beam. Studieswere conducted using the microscopic observation methods and interferometric methods for estimating the surface condition. The article indicates the need for extensive research focusing on the mechanism of the impact of the laser beam scan strategy on the effect on the material during ablative laser machining. The article summarizes the analysis and discussion of research results.
This paper discusses some of the basic problems involved in laser welding of dissimilar materials with significant differences in melting points. It focuses on the micro and macrostructure of laser welded NiCr-Ir microjoints used in central spark plug electrodes. The joints were produced by welding with and without preheat using an Nd,YAG laser. The structure and composition of the welded joints were analyzed by means of a light microscope (LM) and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer. The microhardness of the weld area was also studied.
AbstractNumerical simulation of laser welding dissimilar joint was presented. Results of butt joint for low carbon and austenitic steels are studied. Numerical calculations based on thermo-mechanical method and phase transformation were used for estimating weld dimensions and joint properties. Unconventional welding method where focused photons beam are used as a heat source were presented. Problems with welding of dissimilar joints, where different composition and thermo physical material properties affect on this phenomena complexity are solved using numerical methods and laser welding technology. Simulation of low carbon and stainless steel joints using SimufactWelding software are presented. Model of heat source within geometry and parameters was programmed. Laser beam welding simulation was performed for estimating parameters for complete joints penetration. Programming welding boundary condition and heat source geometry welding parameters with output power and welding speed rate was estimated. Materials used in simulation process and experimental welding was low carbon construction S235JR and stainless 316L steels in sheets form. Joint properties such as fusion zone and heat affected zones dimensions and stress-strain distribution were calculated. Estimation of complete joint characteristics was obtained using thermo-mechanical simulation method and Marc solver engine.. Experimental trial butt joint welding were performed based on estimated parameters. Welding process was performed using 6kW CO2 laser system. Based on numerical simulation, microstructure analysis, hardness distribution and chemical distribution of fusion zone, properties of obtained joint was studied. Model for simulation of dissimilar laser welding joint was obtained, and properties of obtained joint based on simulation and experiment was studied.
This article presents the results of research on the technology and peripheral properties of laser-welded micro-couplings. The aim of this research was to determine the characteristics of properly made joints and to indicate the range of optimal parameters of the welding process. Thin-walled AISI 316L steel pipes with diameters of 1.5 and 2 mm used in medical equipment were tested. The micro-welding process was carried out on a SISMA LM-D210 Nd:YAG laser. The research methods used were macroscopic and microscopic analyses of the samples, and assessment of the distribution of elements in the weld, the distribution of microhardness and the tear strength of the joint. As a result of the tests, the following welding parameters are recommended: a pulse energy of 2.05 J, pulse duration of 4 ms and frequency of 2 Hz, beam focusing to a diameter of 0.4 mm and a rotation speed of 0.157 rad/s. In addition, the tests show good joint properties with a strength of more than 75% of the thinner pipe, uniform distribution of alloying elements and a complex dendritic structure characteristic of pulse welding.
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