轧制复合厚钢板的界面组织及力学性能

以Q345钢为原料,采用组坯抽真空热轧复合的方法制备了55 mm的厚板,利用OM和SEM观察界面微观组织,结果表明,基体和复合界面组织均为珠光体+铁素体,再结晶细化晶粒效果显著。随累计压下率的增加,界面缺陷减少,界面结合强度提高,当累计压下率达到66.0%时,界面剪切强度达到321 MPa,Z向抗拉强度达到520 MPa,断后伸长率最高达到39.5%,满足GB/T 1591—2008《低合金高强度钢》的要求。但复合界面经强酸深度腐蚀后,即使经多道次轧制变形,其仍然存在被强酸腐蚀的痕迹;同时,冲击试验结果表明,复合界面的冲击功低于母材的冲击功。

Interfacial microstructure and mechanical properties of thick rolled composite steel plates

The thick steel plate of 55mm was prepared by blanking vacuum pumping hot rolling bonding using Q345 steel as raw material. The interfacial microstructure was observed by OM and SEM. The results showed that both the matrix and composite interface were combinations of pearlite and ferrite, and the recrystallization refined the grains remarkably. With the increase in the accumulative reduction ratio, the interface defects reduce and the interface bonding strength is increased. When the accumulative reduction ratio reaches 660%, the interfacial shear strength is 321MPa, Z direction tensile strength is 520MPa, and the maximum elongation after fracture reaches up to 395%, which satisfy the requirements of the standard GB/T 1591 2008 High strength low alloy structural steels. However, the clad interface deeply etched with strong acid still shows corroded traces after multi pass rolling deformation. At the same time, the impact test results show that the impact energy of the clad interface is lower than that of the base metal.