薄壁毛细管圆环闪光对焊成形过程数值模拟

发布时间：2018-03-13 14:24

本文选题：不锈钢　切入点：毛细管圆环　出处：《南昌航空大学》2017年硕士论文　论文类型：学位论文

【摘要】：薄壁不锈钢毛细管圆环是广泛使用于高温、高压、酸碱弱腐蚀性环境的密封元件,在制造此类毛细管圆环时,通常是将直管绕弯成环状,再利用焊接的方法将对口端面焊接起来,形成完整的封闭圆环。因此毛细管圆环的焊接方法和接头部位的性能成为了其密封性能好坏的关键。而闪光对焊由于其自身的特点和优势被广泛应用于该类环型件的对接。故本文针对薄壁不锈钢毛细管圆环,利用有限元软件ABAQUS模拟其闪光对焊的成形过程,并分析了工艺参数对焊件接头成形的影响。基于薄壁不锈钢毛细管圆环(1Cr18Ni9Ti)的基本力学性能参数,建立了材料的本构模型(Johnson-Cook模型)。解决了在建立薄壁不锈钢毛细管圆环闪光对焊模型的过程中关于算法选择、几何模型建立、单元类型选择与网格划分、载荷和边界条件等关键技术问题。基于ABAQUS/Explicit模块,建立了兼顾模拟精度和计算效率的薄壁不锈钢毛细管圆环闪光对焊成形过程的三维弹塑性有限元模型,并通过实验验证了模型的可靠性。在所建立的薄壁不锈钢毛细管圆环闪光对焊的有限元模型的基础上,系统地研究了焊接成形过程的应力应变以及焊件上质点位移的分布和变化规律。研究发现,焊件上的等效应力、等效塑性应变均随成形过程不断增大,且除距离对口端面0.2 mm及其附近区域出现轴向拉应力外,焊件其余部位全部受轴向压应力。等效塑性应变与焊件质点位移的分布规律相似,均在焊件对口端面处出现最大值,等效塑性应变最大值为1.102。基于上述三维有限元模型,研究了工艺参数对焊接成形过程接头部位飞边高度和斜度的影响,进而分析工艺参数对焊件接头成形的影响。研究发现,顶锻速度对焊件的接头成形影响不大;顶锻留量对接头成形的影响较为显著,顶锻留量越大则接头部位的塑性变形程度也越大,且当顶锻留量小于1.6mm时,焊件接头部位的塑性变形程度明显不足,不利于接头的成形;调伸长度对焊接过程的温度场和接头部位的成形都有影响,调伸长度越小,焊件轴向上的温度场分布越窄,当调伸长度为2.3 mm时,焊件接头部位的塑性变形程度最大,成形效果最好。
[Abstract]:Thin-walled stainless steel capillary rings are widely used in high-temperature, high-pressure, acid-base weakly corrosive environments. In the manufacture of such capillary rings, the straight tube is usually wound into a ring. Using welding methods to weld the face of the corresponding end, Therefore, the welding method of capillary ring and the performance of joint position become the key to the sealing performance of capillary ring. Flash butt welding is widely used in this kind of ring type because of its own characteristics and advantages. Therefore, this article aims at thin wall stainless steel capillary ring, The forming process of flash butt welding was simulated by finite element software ABAQUS, and the influence of process parameters on joint forming was analyzed. Based on the basic mechanical properties of thin wall stainless steel capillary ring 1Cr18Ni9Ti. The Johnson-Cook model of material is established, which solves the problems of algorithm selection, geometric model establishment, element type selection and mesh generation in the process of establishing thin wall stainless steel capillary ring flash butt welding model. Based on ABAQUS/Explicit module, a three-dimensional elastic-plastic finite element model of thin-walled stainless steel capillary ring flash butt welding forming process is established based on ABAQUS/Explicit module. The reliability of the model is verified by experiments. Based on the established finite element model of capillary ring flash butt welding of thin-walled stainless steel, The stress and strain of welding forming process and the distribution and variation law of particle displacement on welding parts are studied systematically. It is found that the equivalent stress and plastic strain increase with the forming process. Except for the axial tensile stress of 0.2 mm from the opposite end face and its adjacent area, all the other parts of the welding piece are subjected to axial compression stress. The equivalent plastic strain is similar to the distribution law of the particle displacement of the welding piece, and the maximum value appears at the opposite end face of the welding piece, and the equivalent plastic strain is similar to the distribution law of the particle displacement of the welding piece. The maximum value of equivalent plastic strain is 1.102. Based on the above three-dimensional finite element model, the effects of process parameters on flange height and slope of welding joint are studied, and the effects of process parameters on welding joint forming are analyzed. The effect of forging speed on joint forming is not significant, and the effect of top forging retention on joint forming is more significant, and the plastic deformation degree of joint is larger with the increase of top forging retention, and when the top forging retention is less than 1.6 mm, the plastic deformation degree of joint is larger when the top forging retention is less than 1.6 mm. The degree of plastic deformation of the joint is obviously insufficient, which is not conducive to the forming of the joint, and the adjusting elongation has an effect on the temperature field of the welding process and the forming of the joint. The smaller the adjusting elongation, the narrower the distribution of the temperature field in the axial direction of the welding piece. When the elongation is 2.3 mm, the plastic deformation is the largest and the forming effect is the best.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.11

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