| In this paper, the HSLA Q345B slab was researched the high temperature mechanical properties, by using the thermal simulation testing machine that named Gleeble-1500D made single-pass compression and tensile tests in high temperatures to simulate the actual produce process of straightening and rolling. Then, it determined the recrystallization activation energy and high temperature brittleness l, and analyzed deformation characteristics of high temperature and fracture mechanism with Q345B steel. This provided a theoretical guidance for producing high quality and performance casting slab in actual process, the specific results are as follows:The Q345B slab has hot deformation equation that can be expressed as Z =ε. exp[445150/(8.31T )], the peak and steady-state activation energy are respectively 445.15 kJ .mol-1 and 441.96 kJ .mol-1 .When deformated under strain rate of 1.5×10-3/ s and 2.5×10-3/ s, the Q345B slab existed obviousⅢbrittlement that was located at 800℃, the worst plastic has minimized shrinkage value of 22.56%; the best plastic that the area reduction rate reached a maximum of 96.76% occurred at 1000℃. In the strain rate of 2.0×10 -2/ s, it appears less obviousⅡb rittlement (900-1200℃), in order to prevent making cracks when in straightening process, the straightening temperature should more than 850℃in actual continuous casting process.The experimental steel Q345B has a ductility groove that is bottom temperature of 800℃. First is due to the thin layer of ferrite precipitation, which has lower strength, and the second is because precipitated carbonitride inclusion of V, Ti, Nb along the grain boundary, the former two reasons lead to embrittlement of grain boundary. |
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