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The article deals with welding of HSS steel type DOMEX using power fiber laser. They were made weld of steel itself DOMEX and heterogeneous weld with deep drawing steel DC01, which are important for tailored blanks. For all welds were evaluated mechanical properties, macro and microstructure by optical microscopy and (partially) by electron microsc...
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A 100 kW fiber laser was first used to weld steel. Speeds at the range between 0.3 and 5.0 m/min were tested, and the maximum weld bead depth of 70 mm was achieved by single pass welding. Solidification cracking and porosity occurred when the welding speed was lower than 0.5 m/min, while undercut appeared when the welding speed was higher than 3.0...
In the investigation at hand, sheets of ferritic and pearlitic grey cast iron with spheroidal graphite are welded using a fiber-laser. The influence of varying laser power and welding speed on the macroscopic characteristics of the weld seam and crack formation are analyzed and discussed. Substantial crack formation with crack densities of up to 2....
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Citations
... Ultra-high strength steels (UHS) and high strength steels (HS) are advanced materials providing a combination of strength, ductility, toughness, high strength to weight ratio, ease of manufacturability and cost effective manufacturing. These steels are used mainly in automotive industry and in heavy loaded structures such as bridges, pressure vessels, drilling rigs, cranes, excavators, working at room or lower temperatures [1,5,6]. High strength steels with fine grains possess good weldability and plastic deformability, and thus they are promising engineering materials for the future. ...
Nowadays, the use of high strength (HS) and ultra-high strength steels (UHS) increases, notably in welded constructions. These steels are mainly exploited in heavy loaded welded constructions such as bridges, cranes and excavators, in pressure vessels, vehicles, ships, drilling rigs etc. working at room or lower temperatures. As the welded constructions have specific requirements, the development of high strength and ultra-high strength steels imposes the need for research on the factors influencing their weldability. Among the possible negative implications are: cold cracks formation, softening of the heat affected zone, brittleness in the coarse grained zone. When complying with the generally accepted rules for welding, HS and UHS are readily welded by all conventional welding methods. Recommendations for welding of steels after normalization, thermo-mechanical treatment and quenching and tempering are given in the standard EN 1011 -1, 2. The use of thermo-mechanically treated (hot-rolled) steels with low carbon equivalent, such as S700MC, allows reduction in time required for welding as the preheating temperature is lowered or even preheating is not necessary. A more pronounced negative effect on the weld quality has the presence of different defects. S700MC can be welded by all conventional methods, and a reduction in the softened zone can be achieved by using appropriate welding parameters. Joint preparation for welding of HS and UHS steels is described in the standards EN ISO 9692-1:2013 and EN ISO 9692-2:2001. Nevertheless, the root gap is often the closing part in constructions and does not comply with the standard recommendations. That is why the effect of the root gap on welds has to be researched. The present work introduces results of a research studying the effect of the root gap on the structure and some mechanical and technological properties of S700MS welds, welded by submerged arc welding.
... The heat input (E in kJ/mm) was calculated according to the following formula (Mrňa, Kopecký, Němeček, Mikmeková, & Dohnal, 2013): ...
Since gas metal arc welding (GMAW) is a common procedure to join different sheets in the industry, the welding direction dependence on the rolling direction was investigated for a welded DP1000, a cold-rolled dual phase steel. Microstructural investigations and mechanical tests were conducted on two weldments; one being welded parallel to the rolling direction and the second transverse to the rolling direction and the results were compared. It was found that there is a higher degree of softening of the heat-affected zone in the sample welded parallel to the rolling direction. Although this softening did not significantly decrease the tensile strength or the hardness of this sample when compared to the one welded transverse to the rolling direction, the elongation was twice as high in the former sample. That is related to the slower heat dissipation in the sample welded parallel to the rolling direction as confirmed by its microstructural products.
