Ti微合金化700MPa级集装箱用耐候钢的组织性能

Microstructure and properties of Ti microalloyed 700 MPa weathering steel for container

采用变形热膨胀相变仪测定了700 MPa级集装箱用耐候钢的奥氏体连续冷却曲线,并对实验钢进行轧制及周期浸润腐蚀实验,研究了实验钢的奥氏体连续冷却转变行为,轧制工艺对组织性能的影响以及实验钢在工业大气环境下的腐蚀行为。结果表明,所制备的高强耐候钢综合性能优异,屈服强度在770 MPa以上,抗拉强度在840 MPa以上,伸长率达到16%。实验钢的组织为均匀细小的贝氏体,第二相粒子主要是TiC,尺寸在100 nm以下,纳米级含Ti析出相起到了良好的细化组织和析出强化效果。实验钢具有良好的耐大气腐蚀性能,其相对Q345B的腐蚀速率为50.7%,与Q345B相比,耐候钢在腐蚀过程中所生成的锈层更加均匀致密,与基体结合更加牢固,对基体具有更强的保护能力。

Austenite continuous cooling curves of 700 MPa-class container weathering steel were measured by deformation thermal expansion phase change instrument, and the rolling and periodic infiltration corrosion experiments of the experimental steel were carried out. The austenite continuous cooling transformation behavior of the experimental steel, the effect of rolling process on its microstructure and properties, and its corrosion behavior in industrial atmospheric environment were studied. The results show that the prepared high strength weathering steel has excellent comprehensive properties, the yield strength is above 770 MPa, the tensile strength is above 840 MPa, and elongation reaches 16%. The microstructure of the experimental steel is fine and uniform bainite, the second phase particles are mainly TiC, with the size less than 100 nm, and the nanoscale Ti precipitation phase has a good effect on microstructure refinement and precipitation strengthening. The experimental steel has a good resistance to atmospheric corrosion and its corrosion rate is 50.7% of that of the Q345 B steel. Compared with the Q345 B steel, the rust layer produced by weathering steel during corrosion is more uniform and denser, and the combination with the matrix is firmer, leading to a stronger protective ability to the matrix.