Analysis Of The JCO Forming Mechanism For Large Diameter Nickel Base Alloy Thick-walled Welded Pipes

Nickel-based alloys have the advantages of good plasticity,high temperature corrosion resistance and hot and cold forming,so nickel-based alloy thick-walled tubes have a wide range of applications in the transportation of oil,gas and other fields.In the production of nickel-based alloy thick-walled tubes,the most used and the most important method is JCO forming.In actual production,this method is flexible,adaptable,but the forming route is long,there are many processes,and its complex process relationship has a certain impact on the final product quality.Therefore,this paper will analyze and study the process parameters of this forming process to provide guidance and reference for later practice.In this paper,the forming process of LSAW pipe,the process method and the current status of domestic and international research on plate bending theory are briefly introduced.Secondly,based on the elasto-plastic bending theory,the bending and forming mechanism of thick plate is studied,considering the thick plate thickness direction characteristics and neutral layer offset,and the maximum bending moment of the cross section is deduced by mathematical analysis method according to the distribution of stress-strain during bending of thick plate;then,according to the continuous bending characteristics of JCO,the geometric relationship is comprehensively analyzed,and the symmetrical and asymmetrical bending in the forming process of JCO are established respectively.The mathematical models of symmetric and asymmetric bending in the JCO forming process were established,the calculation equations for different bending modes were derived,and the relationships between variables such as bending radius,die size,forming angle and forming force were given;Matlab was used to program the mathematical models and form the corresponding processing interface to complete the calculation of the data;DEFORM software was used to simulate the whole JCO forming process and analyze the rebound of the thick plate after bending and the distribution of stress during Finally,the experimental data were compared with the calculated values by using tensile test,three-point bending test and JCO forming test to verify the results,which proved the feasibility of the mathematical model of JCO bending and forming of thick plate,calculated the error range in the process of JCO forming and analyzed the causes of the error.It can provide some reference for the subsequent JCO forming process for thick plates.