Browsing by Subject "laser welding"

Now showing 1 - 4 of 4

Access status: Open Access ,
Characterization of microstructure and mechanical properties of laser-welded stainless steels
(Wydawnictwa AGH, 2016) Koclęga, Damian; Radziszewska, Agnieszka; Kąc, Sławomir; Zowczak, Włodzimierz; Dębowska, Aleksandra; Jędrusik, Mateusz; Petrzak, Paweł
This work presents the laser welding of dissimilar X12CrCoWVNbN12-2-2 and X10CrNi18-10 steels. This system is of interest, as laser welding offers new flexibility in the joining of metals and laser welds (LWs) and are usually of high quality, they are obtained only after the optimization of process parameters. The aim of the work was to investigate the microstructure, chemical composition, and hardness changes of laser-welded steels. After laser welding, two zones were generated in the processed materials: a fusion zone and a heat-affected zone. Due to solidification, a refinement of the microstructure occurred in the fusion zone. Examinations of the chemical composition of particular melted areas showed the occurrence of Nb-rich precipitations. The laser welding of steels led to increased hardness in the fusion zone (about 240–530 HV0.3).
Access status: Open Access ,
Influence of welding techniques on microstructure and hardness of steel joints used in automotive air conditioners
(Wydawnictwa AGH, 2017) Noga, Piotr; Węglowski, Marek Stanisław; Richert, Maria Wiesława; Zimierska-Nowak, Patrycja; Dworak, Jerzy Maciej; Rykała, Janusz
Austenitic steels belong to a group of special-purpose steels that are widely used in highly aggressive environments due to their enhanced anticorrosive behavior and high mechanical properties. The good formability and weldability of these materials has made them very popular in automotive AC systems. This study presents the results of hardness tests and microstructure observations on plasma- and laser-welded joints. The examined joints consisted of two different stainless steel components, i.e., a nipple made from corrosion-resistant AISI 304 steel and a corrugated hose made from 316L steel. Microplasma welding was carried out on a workstation equipped with an MSP-51 plasma supply system and a BY-100T positioner. The laser-welded joint was made on a numerically controlled workstation equipped with an Nd:YAG laser (without filler material) with 1 kW of maximum power, the rotational speed of the welded component was n = 4 rpm. Microstructural observations were performed using a scanning electron microscope and an optical microscope. Vickers hardness was measured with a hardness tester. The obtained results proved that both the microplasma- and laser-welded joints were free from any visible welding imperfections. In the micro areas of the austenitic steel weld, crystals of intercellular ferrite appeared against a background of austenite. The crystallization front (depending on the welding technology) was running from the fusion line towards the weld axis. The grain size depended on the distance from the fusion line.
Access status: Open Access ,
Microstructure evaluation of laser-welded 600 nickel alloy
(Wydawnictwa AGH, 2016) Tuz, Lechosław
This paper presents the results of a microstructure analysis of a laser butt-welded 600 nickel alloy. A microstructure evaluation of the joint is carried out with the use of light microscopy and scan- ning electron microscopy. The results indicate a phase γ with some particles in the grain boundaries in the base metal. In the weld, a cellular-dendritic structure was observed.
Access status: Open Access ,
Numerical modelling of continuous laser welding of S355J2 steel using a volumetric heat source
(Wydawnictwa AGH, 2023) Siwek, Aleksander; Kąc, Sławomir; Pikuła, Janusz
Numerical modelling of laser welding requires that numerous strongly coupled physical phenomena be taken into account. A laser is a source of welding heat characterized by the small size of the heating volume and the shape of the fusion zone has a marked impact on the quality of the weld. In this work, a conical heat source was used with geometrical parameters to give the appropriate profile of the fusion line. The use of the weld shape factor and the dependence of the power density on the linear welding energy increases the accuracy of matching the calculated shape of the fusion line. The heat source was tested for the continuous welding case of a sheet made of steel type S355J2. The CFD software ANSYS Fluent was used to calculate the welding model. The temperature field, calculated using the finite volume method, was used to calculate the phase composition and fusion zone profile tracking. The nodes of the model reaching the maximum solidus temperature of S355J2 steel, form the profile of the fusion zone. The laser welding model allows for tracking of the kinetics of phase transformations in the cooling stage. Continuous cooling transformation phase diagram data is loaded for the welded steel grade. The calculation results of the welding model were compared with the weld micrographs.