Formation mechanism and elimination measures of 2Cr13 seamless steel tube inner folding in rotary tube piercing process
YIN Yuan-de1,2, ZHANG Si-yu2, WANG Chun-kai3, GUO Zhao-sheng3, LI Jun3, WANG Ting2
1. Ministry of Education Key Laboratory of Metallurgical Emission Reduction and Comprehensive Utilization of Resource, Anhui University of Technology, Maanshan 243002, Anhui, China; 2. School of Metallurgy Engineering, Anhui University of Technology, Maanshan 243002, Anhui, China; 3. Jiangsu Changbao Pulaisen Seamless Steel Tube Co., Ltd., Changzhou 213200, Jiangsu, China
Abstract：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 BCK=133.6 mm,the distance between two guide shoes LCK=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.
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2023, Vol. 58 
