The recently developed direct-quenched ultrahigh strength steels (UHSS) possess an appropriate combination of high tensile strength and toughness properties at subzero temperatures down to −80 °C, while simultaneously having low carbon contents, which is beneficial for weldability. In this study, butt joints of Optim 960 QC direct-quenched UHSS with a thickness of 8 mm were welded with a 10 kW fiber laser to evaluate the characteristics of the joints within the range of low to high heat inputs possible for this welding process. The mechanical properties of the joints were studied by subjecting the specimens to a number of destructive tests, namely, hardness and tensile testing, as well as impact toughness testing at temperatures of −40 °C and −60 °C. It was found that high quality butt joints with superior tensile strength and good impact toughness properties at −40 °C could be obtained. However, having a high level of all these properties in the joint narrows the process parameters’ window, and the heat input needs to be strictly controlled.
Fiber Laser Welding of Direct-Quenched Ultrahigh Strength Steels: Evaluation of Hardness, Tensile Strength, and Toughness Properties at Subzero Temperatures
Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received November 16, 2014; final manuscript received March 19, 2015; published online September 9, 2015. Assoc. Editor: Hongqiang Chen.
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Farrokhi, F., Siltanen, J., and Salminen, A. (September 9, 2015). "Fiber Laser Welding of Direct-Quenched Ultrahigh Strength Steels: Evaluation of Hardness, Tensile Strength, and Toughness Properties at Subzero Temperatures." ASME. J. Manuf. Sci. Eng. December 2015; 137(6): 061012. https://doi.org/10.1115/1.4030177
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