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为了研究含V、Ti、Nb微合金Q345B结构钢的高温塑性,利用Gleeble-1500D热模拟试验机对其进行热拉伸试验,分析了在应变速率为1.5×10-3s-1、变形温度700~1 300℃(Δt=100℃)变形条件下的断裂强度和断面收缩率随温度的变化情况。确定Q345B结构钢存在两个脆性区间,即第Ⅰ脆性温度区间为熔点温度1 300℃,第Ⅲ脆性温度区间为850~740℃。通过扫描电镜和光学显微镜对断口形貌及其组织进行了观察,明确了断裂原因,为连铸生产提供一定的理论指导。
In order to study the high temperature plasticity of V, Ti, Nb microalloyed Q345B structural steel, the hot tensile test was carried out on a Gleeble-1500D thermal simulation tester. The tensile test was carried out at a strain rate of 1.5 × 10-3s-1 and a deformation temperature of 700 ~ 300 ℃ (Δt = 100 ℃) under the condition of deformation and the rupture strength of the cross-section shrinkage changes with temperature. It is confirmed that there are two brittle sections in Q345B structural steel, that is, the first brittleness temperature range is 1 300 ℃ and the third brittleness temperature range is 850-740 ℃. The morphology of the fracture and its microstructure were observed by scanning electron microscopy and optical microscopy. The causes of fracture were clarified, which provided some theoretical guidance for continuous casting production.