高温合金GH4169焊接管材减薄成形工艺研究

发布时间：2019-01-01 08:14

【摘要】：高温合金薄壁波纹管主要应用在航天、航空发动机的密封装置,而GH4169高温合金薄壁管的尺寸精度和力学性能是波纹管成形的关键。根据目前的制造工业和装备水平,获取高精度和超薄壁管材成本较高,加工周期长,成品率较低,管坯性能不稳定。因此如何获取机械性能好、尺寸精度高以及成本低的薄壁管成为了一个研究重点。为提高产品品质以及批量生产时的稳定性,本文采用有限元数值模拟结合实验方法进行薄壁管成形工艺参数的优化设计,另外,本文还提出了采用焊接管坯后,进行三辊冷轧与滚珠旋压获得管坯的工艺方案,并与现有成形方案进行了对比实验研究,拟解决现有采用无缝管坯生产成本高,周期长的问题。本文以三辊轧制实际工艺为基础,建立与实际工况一致的三维弹塑性有限元模型,管材从Φ62×1.5mm轧制到Φ45.1×0.65mm,分析工艺参数如送进量、轧制速度、轧槽开口度、减薄率对轧制力的影响,通过比较不同工艺参数对轧制力的影响,优化出最终的三辊轧制工艺参数为进给比为2mm/r,减薄率15%,轧辊上的轧槽开口度为14°。并且分析三辊轧制的接触区域、三辊轧制区域剪应力、轧制力、轴向力的分布规律,进一步了解三辊轧制时管材的变形规律。通过分析管坯在变形区各阶段的变形规律,获得了凸耳的产生原因以及解决措施。有限元分析结果与实验对比具有很好的一致性。本文以滚珠旋压实际工艺为基础,建立与实际工况相近的三维弹塑性有限元模型,管材从Φ45.1×0.65mm旋压到Φ44.8×0.25mm,通过有限元模拟优化工艺参数,得到最终的工艺参数为进给比为进给比为1mm/r,减薄率为37.5%。并分析管材在滚珠旋压下的应力应变分布规律。通过分析隆起区的应力状态与受力状态,研究隆起的成因,以及不同减薄率和不同进给比对旋压成品质量的影响。研究了变形区的流动规律,了解管材的变形规律以及所处的应力状态。采取优化的工艺进行实验生产,有效地提高了产品品质的稳定性。本文通过观察管坯焊接前后的组织对比,发现焊接后的组织是柱状树枝晶组织,然后经过四道次的三辊冷轧,期间配合热处理后,管材上的焊接位置已经难以分辨,观察其金相组织发现,原始的焊缝组织完全转变为均匀组织。然后经过滚珠旋压后,管材达到成品尺寸,金相组织变得更加细小,尤其是在焊缝位置,焊缝位置比基体组织更加细小,晶粒度达到9级,成品管材的屈服强度为458.5MPa、抗拉强度为985.5MPa、断面收缩率为47.5%,无缝管坯加工得到的成品管材没有明显差别,均达到使用要求。
[Abstract]:Thin-wall corrugated tubes of superalloy are mainly used in the sealing devices of aerospace and aero-engine, while the dimensional accuracy and mechanical properties of GH4169 superalloy thin-walled tubes are the key to forming the corrugated tubes. According to the current manufacturing industry and equipment level, the production cost of high precision and ultra-thin wall pipe is high, the processing period is long, the finished product rate is low, and the performance of tube billet is unstable. Therefore, how to obtain thin-walled tubes with good mechanical properties, high dimensional accuracy and low cost has become a research focus. In order to improve product quality and stability in batch production, this paper adopts finite element numerical simulation combined with experimental method to optimize the process parameters of thin-walled tube forming. The process scheme of cold rolling and ball spinning with three rollers was carried out to obtain tube billet, and compared with the existing forming scheme, the problems of high production cost and long period of production of seamless tube blank were solved. Based on the practical technology of three-roll rolling, a three-dimensional elastic-plastic finite element model is established in accordance with the actual working conditions. The tube is rolled from 桅 62 脳 1.5mm to 桅 45.1 脳 0.65 mm. The process parameters such as feed rate, rolling speed, and slot opening degree are analyzed. By comparing the effect of different process parameters on rolling force, the final three-roll rolling process parameters are optimized as feed ratio of 2 mm / r, thinning rate of 15 and groove opening degree of 14 掳. The contact area of three-roll rolling, the distribution law of shear stress, rolling force and axial force in three-roll rolling area are analyzed, and the deformation law of tube during three-roll rolling is further understood. By analyzing the deformation law of tube billet in each stage of deformation zone, the causes and solutions of convex ear are obtained. The results of finite element analysis are in good agreement with the experimental results. Based on the actual process of ball spinning, a three-dimensional elastic-plastic finite element model is established, which is close to the actual working conditions. The tube is spun from 桅 45.1 脳 0.65mm to 桅 44.8 脳 0.25mm, and the process parameters are optimized by finite element simulation. The final process parameters are feed ratio of 1 mm / r and thinning rate of 37. 5%. The distribution of stress and strain of pipe under ball spinning is analyzed. By analyzing the stress state and the stress state in the uplift area, the causes of the uplift and the influence of different thinning rate and feed ratio on the quality of spinning products are studied. The flow law of the deformation zone is studied, and the deformation law and the stress state of the pipe are understood. The stability of the product quality is improved effectively by adopting the optimized technology to carry on the experiment production. By observing the microstructure of tube billet before and after welding, it is found that the microstructure after welding is columnar dendritic structure, and then after four passes of three rolls cold rolling, the welding position on the tube is difficult to distinguish after heat treatment. The metallographic structure of the weld was observed and the original weld microstructure was completely transformed into uniform microstructure. Then after the ball spinning, the tube reaches the finished size, and the metallographic structure becomes smaller, especially in the weld line, where the weld is smaller than the matrix, the grain size reaches 9, and the yield strength of the finished pipe is 458.5 MPA. The tensile strength is 985.5 MPa and the cross section shrinkage is 47.5%. The finished tubes produced by seamless tube blank processing have no obvious difference and all meet the requirements of application.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG457.6;TG306

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