Abstract
For Q345C steel MAG welded joints, low temperature tensile test was carried out at normal atmospheric temperature, 0°C,-20°C,-30°C and-40°C in the paper, which results in the law of strength change with temperature. The impact absorption energy of the weld seam sample under different temperature conditions was tested, impact fracture morphology was observed and the parentage of the fibrous fracture surface was assessed. The curve of impact absorption energy and the percentage of the fibrous fracture surface with temperature were fitted by using the Boltzmann function, and ductile brittle transition temperature of Q345C steel MAG welded joints was determined. The test results show that the impact absorption energy of the weld seam can reach 71J at-40°C, and the weld seam is prone to brittle fracture under low temperature. The influences of alloying elements and microstructure on the ductile brittle transition temperature and low temperature impact toughness were discussed, and suggestion is put forward to improve the impact toughness and reduce the ductile brittle transition temperature.
Published Version
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