2Cr13钢无缝管内折叠的形成机理和消除措施

Formation mechanism and elimination measures of 2Cr13 seamless steel tube inner folding in rotary tube piercing process

为了研究某钢管公司2Cr13钢无缝管实际生产中出现的内折叠缺陷问题,在测定2Cr13钢高温力学性能的基础上,借助于有限元软件Simufact,通过Oyane韧性断裂损伤场模拟预测了2Cr13钢的临界压下率范围,并对典型规格2Cr13钢管现有工艺穿孔过程进行三维弹塑性有限元模拟,分析了穿孔过程中轧件的应力/应变分布、温度场、力能参数及内折叠缺陷形成的倾向性,在此基础上研究了不同的穿孔调整参数对穿孔内折叠及轧卡倾向性的影响。结果表明,2Cr13钢临界压下率在6.0%~6.5%之间,穿孔不发生内折叠且二次咬入顺利的顶前压下率范围较窄,工艺调整范围较小;轧辊入口锥摩擦因数增大,利于穿孔的二次咬入,同时减小轧辊磨损及内折叠的发生;现行工艺穿孔时,在距离管坯前端面约80 mm处,管坯中心点三向正应力均为拉应力且同时达到最大,最大横向、径向和轴向拉应力分别为87.30、12.39和53.38 MPa;在该处及其附近区域管坯中心发生了内撕裂,进而产生穿孔内折叠缺陷;将顶前压下率由原工艺的6.39%调整为5.75%,穿孔过程中轧件中心不发生内撕裂现象,不产生内折叠缺陷。优化的调整参数为,轧辊辊距B_(CK)=133.6 mm,导板距L_(CK)=145 mm,顶头前伸量b=89 mm。通过现场生产探伤数据对模拟结果的正确性进行了验证。

In order to study the inner folding defect of 2Cr13 steel seamless tube in actual production of a steel pipe company,based on the determination mechanical properties of 2Cr13 steel at high temperature,a three-dimensional elastoplastic finite element simulation of the existing process of the typical specification 2Cr13 steel rotary tube piercing process with the help of finite element software Simufact was constructed.The critical reduction rate range of 2Cr13 steel was predicted by Oyane ductile fracture damage field simulation,and the stress/strain distribution,temperature field,force energy parameters and tendency of inner folding defects of pierced shell during the rotary piercing process were analyzed.Furthermore,the influence of different rotary piercing adjustment parameters on the inner folding and rolling block tendency was studied.The results show that the critical reduction rate range of 2Cr13 steel is between 6.0%and 6.5%,and the reduction rate range before plug is narrow which does not occur inner folding and the second bite is smoothly,so the process adjustment range is small.Increasing the friction coefficient of the roll inlet cone,is beneficial to the secondary bite of the perforation,and reduces roll wear and the occurrence of inner folding defect.In the current rotary piercing process,at about 80 mm away from the front end of the pierced shell,the three-direction normal stresses at the center point of the pierced shell are tensile stresses and reach the maximum value at the same time,and the maximum transverse,radial and axial tensile stresses are 87.30,12.39 and 53.38 MPa,respectively,and the internal tear occurs in the center of the pierced shell at above area and its vicinity,which results in the inner folding defect.The reduction rate before plug is adjusted from 6.39%of the original process to 5.75%,and the internal tear phenomenon does not occur in the center of pierced shell during the rotary piercing process,and the inner folding defect is not generated.The optimized adjustment parameters are as follows.The distance between two roll high points B_(CK)=133.6 mm,the distance between two guide shoes L_(CK)=145 mm,the distance of the front end of plug b=89 mm.The correctness of simulation results were verified by the inspection data from practical production.