(1. 江蘇理工學院 機械工程學院，常州 213001;
2. 東北大學 材料科學與工程學院，沈陽 110189)
摘 要: 對退火態(tài)Al/Al板在室溫下進行同步和異步復合軋制實驗，發(fā)現(xiàn)同步軋制后的Al/Al板界面發(fā)生焊合，而異步軋制使已焊合的Al/Al板界面又出現(xiàn)分離。為了進一步驗證Al/Al板界面焊合與分離現(xiàn)象，分別對同步和異步軋制后的試樣進行拉伸實驗，并觀察拉伸斷口的SEM像。分析認為：同步軋制時軋件表面受到的縱向剪應力最大，而軋件厚度二分之一處(對稱面)的縱向剪切應力為0，這種剪應力分布有利于復合界面在強大壓應力下實現(xiàn)焊合；相比之下，異步軋制存在搓軋區(qū)，搓軋區(qū)中的縱向剪應力沿軋件厚度方向分布均勻，即Al/Al結(jié)合界面受到的縱向剪應力與軋件表面處幾乎相等，此剪應力對已經(jīng)焊合的界面產(chǎn)生破壞作用，導致焊合面發(fā)生剪切分離。為了深入探究同步軋制焊合與異步軋制分離的機制，采用有限元方法進行模擬，得到異步軋制下Al/Al界面處縱向剪應力為57.8 MPa，達到工業(yè)純鋁復合界面的剪切強度，足以引起焊合面的剪切分離。這為詮釋異步軋制下的界面分離現(xiàn)象提供了佐證，這些研究結(jié)果對層狀金屬復合軋制方式的選擇具有較大的參考價值。
關鍵字: 鋁板復合；軋制；界面焊合；界面分離；異步軋制；同步軋制
（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
