Guillaume Rückert

Hybrid laser-metal active gas welding of S460ML steel plates: Weldability and consequences of dropping on weld quality

This work investigates the weldability of S460ML steel using a hybrid laser-metal active gas (MAG) process and the effect of dropping on material properties. Dropping is the creation of regularly scattered drops on the back side of thick plates during full penetration hybrid laser-MAG welding. As these drops can reach several millimeters in diameter, it is an unacceptable defect since it lowers esthetic properties. Besides the geometrical aspect, mechanical properties are also affected by dropping. In order to check the consequences of dropping on weld quality: metallographic, mechanical, and dilution analyses have been performed. Results confirm the good weldability of S460ML using hybrid welding with proper welding parameters. If dropping occurs, it enhances heterogeneity in chemistry and microstructure, and welding defects such as porosity and undercuts. However, these properties and defects remain tolerable. Drops can be removed by grinding, making the weld acceptable.

Evaluation of FSW on High Yield Strength Steels for Shipbuilding

FSW process has been evaluated on three shipbuilding steels (DH36, S690QL and 80HLES steels) by fully penetrated butt welds on 8mm thick plates. Non destructive tests were carried out to highlight the presence of intrinsic defects known for the welding process (eg kissing bond). The validated inspection methodology (volume and surface testing) confirm the integrity of welds and the absence of geometrical defects for examinations and mechanical tests as part of a qualification procedure.

Metallurgical Study of Friction Stir Welded High Strength Steels for Shipbuilding

Friction Stir Welding (FSW) is one of the most recent welding processes, invented in 1991 by The Welding Institute. Recent developments, mainly using polycrystalline cubic boron nitride (PCBN) tools, broaden the range of use of FSW to harder materials, like steels. Our study focused on the assembly of high yield strength steels for naval applications by FSW, and its consequences on the metallurgical properties. The main objectivewas to analyze the metallurgical transformations occurring during welding. Welding tests were conducted on three steels: 80HLES, S690QL and DH36. For each welded sample, macrographs, micrographs and micro-hardness maps were performed to characterize the variation of microstructures through the weld.

Enhanced Weld Penetrations In GTA Welding with Activating Fluxes Case studies: Plain Carbon & Stainless Steels, Titanium and Aluminum

Flux applications prior to the convention Gas Tungsten Arc Welding (GTAW) is known to improve weld penetrations and improve process competitiveness. This paper summarizes the investigations on aluminum, plain carbon steels, stainless steels and titanium. The importance of flux composition, homogeneity and profile of its application are shown to be primordial in determining the weld depth to width ratio of weld pools. The mechanisms that lead to improved penetrations along with some industrial case studies are presented.Key Words: ATIG, Weld penetrations, Steels, Titanium, Aluminum