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Comparison between GTA and laser beam welding of 9% Ni steel for critical cryogenic applications

: El-Batahgy, A-M.; Gumenyuk, A.; Gook, S.; Rethmeier, M.


Journal of materials processing technology 261 (2018), pp.193-201
ISSN: 0924-0136
Bundesministerium für Bildung und Forschung BMBF
01DH14012; LoWELL
Laserstrahl- und Laserhybridschweißen von vergüteten 9% Ni Stählen für Konstruktion von LNG-Anlagen aus sauberen Energiequellen
Journal Article
Fraunhofer IPK ()
9%Ni steel; GTAW; laser beam welding; fusion zone size; microstructure; tensile strength; impact absorbed energy

In comparison with GTA welded joints, higher tensile strength comparable to that of the base metal was obtained for laser beam welded joints due to fine martensitic microstructure. Impact fracture toughness values with much lower mismatching were obtained for laser beam welded joints due to similarity in the microstructures of its weld metal and HAZ. In this case, the lower impact fracture toughness obtained (1.37 J/mm2) was much higher than that of the GTA welded joints (0.78 J/mm2), which was very close to the specified minimum value (≥0.75 J/mm2). In contrast to other research works, the overall tensile and impact properties are influenced not only by the fusion zone microstructure but also by the size of its hardened area as well as the degree of its mechanical mismatching, as a function of the welding process. A better combination of tensile strength and impact toughness of the concerned steel welded joints is assured by autogenous laser beam welding process.