轧制工艺对工业化试制的真空组坯Q345R/304复合板组织性能的影响

Influence of rolling process on microstructure and propeties of industrial produced Q345R/304 clad plate

山西太钢不锈钢股份有限公司利用真空组坯复合轧制(真空电子束焊接+轧制复合)技术工业化试制了Q345R/304复合板。本文研究了常规轧制和控轧控冷工艺下轧制复合板的界面结合率、常规力学性能、界面结合强度和界面附近的显微硬度和显微组织变化。结果表明:界面结合不良来自于复合界面处形成的硅铝氧化物和铬锰氧化物,这可能是由于组坯时真空度不足、加热过程中形成的氧化产物。两种工艺下界面附近显微组织差异明显,沿远离界面方向,常规轧制的Q345R钢板组织沿厚度方向为均匀的块状铁素体和珠光体组织,304钢板组织已完全再结晶;控轧控冷工艺轧制的Q345R钢板组织沿厚度方向由多边形铁素体和珠光体组织向针状铁素体和贝氏体组织过渡,304钢板组织仍有变形特征。力学性能检测表明:常规热轧复合板的屈服强度和抗拉强度比控轧控冷复合板分别低115、71 MPa,强度裕量较小;纵向冲击功不小于130J,外弯、内弯、侧弯后无裂纹,复合板剪切强度在350 MPa以上,高于标准要求(不小于210 MPa),线扫描结果表明界面附近已存在由元素扩散形成的浓度梯度。

The Q345R/304 clad plate was manufactured by vacuum electron beam welding and rolling method.The interfacial bonding rate,mechanical properties,interfacial bonding strength,micro-hardness and microstructural changes of the rolled clad plates by conventional rolling process and TMCP process were investigated.The results showed that the interfacial bonding defects were attributed to formation of Si-Al and Cr-Mn oxides at the interface.Meanwhile,the microstructures near the interfaces were also different.The microstructure of Q345 Rplate produced by conventional rolling was uniform ferrite and pearlite,and the microstructure of the 304 plate was completely recrystallized.However,the microstructure of Q345 Rplate produced by TMCP was from polygonal ferrite and pearlite structure to acicular ferrite and bainite structure along the thickness direction,and the microstructure of 304 plate was still unrecrystallized.The mechanical results showed that the yield strength and tensile strength of conventional rolled clad plate were lower by 115 MPa and 71 MPa than that of TMCP produced clad plate.The longitudinal impact energy of clad plate was not less than 130 J,and the shear strength of the clad plate was above 350 MPa,which was higher than the standard requirement（over 210MPa）.The EDS results showed that the concentration gradient by diffusion had formed near the interface.