(1. 江苏理工学院 机械工程学院，常州 213001;
2. 东北大学 材料科学与工程学院，沈阳 110189)
摘 要: 对退火态Al/Al板在室温下进行同步和异步复合轧制实验，发现同步轧制后的Al/Al板界面发生焊合，而异步轧制使已焊合的Al/Al板界面又出现分离。为了进一步验证Al/Al板界面焊合与分离现象，分别对同步和异步轧制后的试样进行拉伸实验，并观察拉伸断口的SEM像。分析认为：同步轧制时轧件表面受到的纵向剪应力最大，而轧件厚度二分之一处(对称面)的纵向剪切应力为0，这种剪应力分布有利于复合界面在强大压应力下实现焊合；相比之下，异步轧制存在搓轧区，搓轧区中的纵向剪应力沿轧件厚度方向分布均匀，即Al/Al结合界面受到的纵向剪应力与轧件表面处几乎相等，此剪应力对已经焊合的界面产生破坏作用，导致焊合面发生剪切分离。为了深入探究同步轧制焊合与异步轧制分离的机制，采用有限元方法进行模拟，得到异步轧制下Al/Al界面处纵向剪应力为57.8 MPa，达到工业纯铝复合界面的剪切强度，足以引起焊合面的剪切分离。这为诠释异步轧制下的界面分离现象提供了佐证，这些研究结果对层状金属复合轧制方式的选择具有较大的参考价值。
关键字: 铝板复合；轧制；界面焊合；界面分离；异步轧制；同步轧制
（1. School of Mechanical Engineering, Jiangsu University of Technology, Changzhou 213001, China;
2. School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China）
Abstract:Annealed Al/Al plates were rolled by symmetrical and asymmetrical rolling at room temperature. Based on the optical microscopy observation, the Al/Al plates were welded by symmetrical rolling, and the welded Al/Al plates were again separated by asymmetrical rolling. In order to further confirm the phenomenon of interface welding and separation of the Al/Al plates, the tensile tests were carried out on the samples after symmetrical and asymmetrical rolling, and the tensile fractures of the samples were observed by scanning electron microscopy. It is considered that the longitudinal shear stress acting on the surface of the rolled piece is the largest for symmetrical rolling, and the longitudinal shear stress acting on the plane at one-half of the thickness of the rolled piece (plane of symmetry) is zero. Such shear stress distributions are good for the welding of the interface. In contrast, for asymmetrical rolling, the longitudinal shear stress in cross-shear zone is uniformly distributed along the thickness direction of the rolled piece, i.e., the longitudinal shear stress acting on the Al/Al interface is almost equal to that acting on the surface of rolled piece. However, the longitudinal shear stress can also destroy the welded Al/Al interface, resulting in a separation at the welded interface. In order to obtain the welding mechanism of symmetrical rolling and the separation mechanism of asymmetrical rolling, the finite element method was used to simulate the two rolling processes. The simulation results show that the longitudinal shear stress at the Al/Al interface in asymmetrical rolling is 57.8 MPa, which reaches the shear strength of aluminum and can cause the shear separation at the welded interface. This provides a strong evidence to explain the phenomenon of interface separation in asymmetrical rolling. The results would be helpful in selecting suitable sandwich rolling process for layered metals.
Key words: aluminum plates; sandwich rolling; interface welding; interface separation; asymmetrical rolling; symmetrical rolling
