6061铝合金累积不均匀变形工艺研究

发布时间：2018-09-13 14:41

【摘要】：6061铝合金具备轻质、高强、耐腐蚀等优良特性,以其制备的精密零件在设备制造、汽车、家居等行业都受到广泛应用。6061铝合金具备良好的成型性能,与之相关的轧制技术发展十分迅速,轧制生产过程的自动化、精密化势必会成为未来的发展趋势。本课题采用异步轧制(Asymmetric Rolling,ASR)和反复弯曲平直轧制(Repetitive Corrugation and straightening,RCS)分别对6061铝合金进行多道次累积不均匀变形加工,并对两种轧制工艺进行对比分析。采用ANSYS/LS-DYNA有限元模拟分析软件,模拟了道次压下率为8%和20%的弯曲变形过程。压下率为8%时,轧后残余应力主要集中在发生弯曲变形位置的板材心部,在材料头部和尾部残余应力较小,轧件与轧辊波峰接触位置金属流动较快,轧后板材变形较为均匀,适用于连续生产。道次压下率为20%时,轧件宽度方向存在较大起伏,不能用于连续生产。分别采用异步轧制和反复弯曲平直轧制对轧件进行加工,其中异步轧制采用1.14、1.26、1.39三组异速比,反复弯曲平直轧制齿型采用半径为18mm和26mm的三段圆弧相切得到。总压下率为30%时,三组异速比(1.14,1.26,1.39)轧制后得到的平均晶粒尺寸为97.8μm、89.3μm、84.1μm,反复弯曲平直轧制轧后晶粒尺寸为79.4μm,在晶界附近存在破碎的小晶粒。随着压下量的增加,三组异速比的轧后晶粒得到不同程度的细化,晶粒被进一步拉长,没有观察到新的晶粒生成。对总压下率30%的轧后试样进行单向拉伸试验,反复弯曲平直轧制相对于异步轧制得到的试样抗拉强度较大,可以达到381MPa,屈服强度为374MPa,但是在强度提高的同时轧件的断后延伸率相应较低,仅为6.31%。随着异速比的增加,轧件的抗拉强度和屈服强度也随之增加,断后延伸率变化较小。
[Abstract]:6061 aluminum alloy has many excellent properties, such as light weight, high strength, corrosion resistance and so on. It has been widely used in equipment manufacturing, automobile, home and other industries. The related rolling technology is developing very quickly. The automation and precision of rolling process will be the trend in the future. In this paper, asynchronous rolling (Asymmetric Rolling,ASR) and repeated bending flat rolling (Repetitive Corrugation and straightening,RCS) are used to process 6061 aluminum alloy for multiple pass cumulative inhomogeneous deformation, and the two rolling processes are compared and analyzed. The bending deformation process with 8% and 20% pass reduction rate was simulated by ANSYS/LS-DYNA finite element simulation software. When the reduction rate is 8, the residual stress after rolling is mainly concentrated in the center of the plate where bending deformation occurs. The residual stress at the head and tail of the material is smaller, the metal flow is faster at the position of contact between the workpiece and the wave peak of the roll, and the deformation of the plate after rolling is more uniform. Suitable for continuous production. When the pass reduction rate is 20, the width direction of the rolling piece fluctuates greatly and can not be used in continuous production. The rolling parts were processed by asynchronous rolling and repeated bending straight rolling respectively. Among them, 1.14U 1.261.39 groups of different speed ratios were used for asynchronous rolling, and the tooth profile for repeated bending straight rolling was obtained by tri-section arc tangent with radius of 18mm and 26mm. When the total reduction rate is 30, the average grain size of the three groups of different speed ratio (1.141.26 / 1.39) after rolling is 97.8 渭 m, 89.3 渭 m and 84.1 渭 m respectively, and the grain size is 79.4 渭 m after repeated bending flat rolling. There are small broken grains near the grain boundary. With the increase of the reduction amount, the three groups of different speed ratio grains were refined to different extent, the grains were further elongated, and no new grain formation was observed. The tensile strength of the specimens after rolling with a total reduction rate of 30% was tested by uniaxial tensile test. The tensile strength of the specimens obtained by repeated bending flat-straight rolling was higher than that obtained by asynchronous rolling. The yield strength and yield strength can reach 381MPa and 374MPa respectively, but the elongation at break of the rolled piece is relatively low at the same time, which is 6.31 MPA. The tensile strength and yield strength of workpiece increase with the increase of the ratio of different speed, and the elongation after break changes little.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG339

【参考文献】