(石家莊鐵道大學(xué) 材料科學(xué)與工程學(xué)院，石家莊 050043)
摘 要: 對設(shè)計的拉伸剪切試樣和原位拉伸剪切試樣分別進(jìn)行不同剪應(yīng)變率下的拉伸剪切試驗及原位拉伸剪切試驗，研究6061鋁合金在剪力狀態(tài)下的力學(xué)性能及斷裂行為，并用有限元軟件ABAQUS對鋁合金在剪應(yīng)力狀態(tài)下的斷裂行為進(jìn)行模擬。結(jié)果表明：隨著剪應(yīng)變率的增大，6061鋁合金的剪切屈服強度和抗剪強度基本保持不變，但剪切斷裂應(yīng)變明顯減小；剪應(yīng)變率對試樣的斷口形貌沒有影響；6061鋁合金晶界是其最薄弱環(huán)節(jié)，在拉伸剪切過程中鋁合金試樣表面上產(chǎn)生了大量與拉伸方向平行的滑移帶；微裂紋在剪應(yīng)力作用下形核于與拉伸方向平行的滑移帶和晶界，隨著剪應(yīng)力的增加，微裂紋長大和擴展；微裂紋之間通過剪切而連接導(dǎo)致試樣斷裂；6061鋁合金剪切斷裂行為可以用Johnson-Cook模型進(jìn)行描述。
關(guān)鍵字: 6061鋁合金；拉伸剪切；原位拉伸剪切；斷裂行為；Johnson-Cook模型
（Institute of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China）
Abstract:The mechanics properties and fracture behaviors of 6061 aluminum alloy were investigated by the tensile shear tests and in-situ tensile shear tests with tensile shear specimen devised. The FEM software ABAQUS can be used to describe the fracture behaviors of 6061 aluminum alloy under shear stress states. The results indicate that with increasing the shear strain rates, the shear yield stress and shear ultimate stress of 6061 aluminum alloy remain constant basically, while the shear fracture strain obviously decreases. The shear strain rates have no influence on the fracture surfaces. A lot of slip bands paralleling to the tensile direction are produced on the specimens’ surfaces. The grain boundaries of 6061 aluminum alloy are the weakest area, and the microcracks initiate at the slip bands and grain boundaries parallel to the tensile direction under shear stress. With increasing the shear stress, the microcracks extend and coalesce. The specimens fracture due to coalescence or shearing between the microcracks. The Johnson-Cook model can be used to describe the fracture behaviors of 6061 aluminum alloy under shear stress states.
Key words: 6061 aluminum alloy; tensile shear; in-situ tensile shear; fracture behavior; Johnson-Cook model
