62528 2025 eng 1 15 article Springer United Kingdom 1 -- -- -- Laser hybrid welding presents several challenges when used to weld thick steels. A typical weld is divided into the arcdominated and laser-dominated zone. These zones lead to variations in the mechanical properties of the weld. The laserdominated zone is of particular importance regarding mechanical properties, notably Charpy impact toughness, due to the high cooling rates and the absence of filler wire. The low heat input of the laser can lead to martensitic microstructure causing hardening and deterioration of impact toughness. The high heat input of the arc can lead to grain coarsening and even loss of impact toughness. This study examines the influence of heat input on the cooling rates, microstructure and mechanical properties of single-pass laser hybrid welded steels of S355J2 and EH36 with thicknesses up to 30 mm. The experiments were performed with a 20-kW fibre laser and a contactless electromagnetic weld backing in the butt-joint configuration in 1G welding position. The cooling time was measured in three different locations near the fusion lines corresponding to different heights of the seam using a special configuration with pyrometers, collimators and optical fibres. The test specimens for the Charpy impact testing and tensile testing were extracted in three different depths. The experiments indicated that a heat input of 1.6 kJ/mm–2 kJ/mm, 2 kJ/mm–2.4 kJ/mm and 3.7 kJ/mm were recommended when single-pass laser hybrid welding of 20-, 25-, and 30-mm-thick structural steels regarding the minimum requirements of the mechanical properties, respectively. Welding in the World 10.1007/s40194-025-01924-8 1878-6669 urn:nbn:de:kobv:b43-625282 publish 10.02.2025 false true Creative Commons - CC BY - Namensnennung 4.0 International Fatma Akyel Ömer Üstündag Nasim Bakir Christian Brunner-Schwer Andrey Gumenyuk Michael Rethmeier eng uncontrolled Laser hybrid welding eng uncontrolled Heat input eng uncontrolled Mechanical properties eng uncontrolled Charpy impact toughness eng uncontrolled Cooling rate Ingenieurwissenschaften und zugeordnete Tätigkeiten 9 Komponentensicherheit 9.3 Schweißtechnische Fertigungsverfahren Material Degradationsmechanismen Verlagsliteratur Datei für die Öffentlichkeit verfügbar ("Open Access") Wissenschaftliche Artikel der BAM Bundesanstalt für Materialforschung und -prüfung (BAM) https://opus4.kobv.de/opus4-bam/files/62528/2025 - Akyel_Influence of heat input on cooling rates and mechanical properties of.pdf