终轧温度对2205/Q345C复合板界面组织和力学性能的影响

采用真空对称组坯+热轧法制备2205/Q345C复合钢板,研究了终轧温度对复合板界面微观组织、元素扩散、硬度分布及剪切强度的影响。结果表明:终轧温度为950~1100 ℃时2205/Q345C复合板的界面结合良好,基层Q345C钢板为铁素体+珠光体组织,复层2205双相不锈钢为奥氏体+铁素体组织。在界面附近,Q345C钢中的C向2205钢中扩散形成了脱碳层,而2205钢形成了“渗碳层”,且二者的深度均随终轧温度的增加而增加。2205钢中的Cr、Ni元素向Q345C钢中连续扩散,Cr原子扩散的剧烈程度高于Ni原子,扩散距离大于Ni原子,且二者的扩散距离均随终轧温度的升高而增加。随着终轧温度的升高,复合板的硬度变化不大,在界面附近2205钢硬度最高而Q345C钢硬度值最低,而界面的剪切强度略有降低,但均大于420 MPa,符合GB/T 8165—2008《不锈钢复合板和钢带》中剪切强度≥210 MPa的要求,且剪切断口中裂纹源区面积减小。终轧温度为950~1100 ℃时2205/Q345C复合板均获得了良好的力学性能。

Effect of final rolling temperature on interfacial microstructure and mechanical properties of 2205/Q345 C steel clad plate

Effect of final rolling temperature on the interface microstructure, element diffusion, hardness distribution and shear strength of 2205/Q345C clad steel plates prepared by vacuum hot rolling method were studied. The results show that the interface of the clad plates are all well bonded when the final rolling temperature is in the range of 950-1100 ℃, which is composed of ferrite + pearlite at the Q345C steel side and austenite + ferrite at the 2205 steel side. Near the interface of clad plate, the C atoms diffuses from Q345C steel into 2205 steel, causing a decarburized layer formed in Q345C steel, while a “carburized layer” formed in 2205 steel, and the thicknesses of both the decarburized layer and “carburized layer” increase with the increase of the final rolling temperature. Meanwhile, the Cr and Ni atoms diffuse continuously from Q345C steel into 2205 steel, and the diffusion distance of Cr atoms is greater than that of Ni atoms. With the increase of the final rolling temperature, the diffusion distances of Cr atoms and Ni atoms increase. Also with the increase of the final rolling temperature, the hardness of the clad plate changes little, and the hardness of 2205 steel near the interface is the highest while that of Q345C steel is the lowest. At the same time, the interfacial shear strength of the clad plates decreases, but all of them are greater than 420 MPa, which conforms to the requirement of shear strength ≥210 MPa in the standard of GB/T 8165—2008 Stainless Steel Clad Plates and Strips. In conclusion, when the final rolling temperature is in the range of 950-1100 ℃, the 2205/Q345C clad plates can obtain good mechanical properties.