Numerical Simulation And Process Optimization Of Cross Rolling Perforation Of Cu-6Ni-6Sn Alloy Based On Modified GTN Model

Cu-6Ni-6Sn alloy is an ideal material for connecting rod bushing because of its high temperature resistance,shock absorption and strong wear resistance.How to prepare low cost and high mechanical properties of Cu-Ni tin alloy tube is the key problem at present.The production of Cu-6Ni-6Sn alloy pipe by extrusion or drawing process not only has low production efficiency but also easily causes serious environmental pollution.The pipe fittings are also prone to cracks and other defects,which seriously affect the mechanical properties and process formability of seamless pipe.If the damage form and location can be simulated through simulation study in advance and the process parameters can be corrected,the development cost of new process can be greatly reduced and the production of new products can be accelerated.Therefore,for the first time in this paper,the modified GTN mesoscopic damage model is introduced into the plastic deformation process of Cu-6Ni-6Sn alloy,and a new cross-rolling perforation technology of Cu-Ni-Tin seamless tube is proposed and optimized.The main research contents are as follows:（1）The flow stress-strain curves of cop-Nic-tin alloy at different temperatures（room temperature,650℃,700℃,750℃ and 800℃）were obtained and the thermal deformation behavior of Cop-Nic-tin alloy was analyzed using Gleeble-3800 thermal simulation tester.The Gleeble-3800 thermal simulation tester was used to conduct the thermal tensile test of Cop-Nic-tin alloy.The flow stress-strain curves of Cu-6Ni-6Sn alloy at different temperatures（room temperature,650℃,700℃,750℃ and 800℃）were obtained,and the thermal deformation behavior of Cu-6Ni-6Sn alloy was analyzed.（2）Based on the uniaxial thermal tensile test,Abaqus finite element simulation software was used for simulation.The response surface method and genetic algorithm were combined to optimize and reverse calibrate the characteristic damage parameters f₀、f_N f_C and f_F in the modified GTN model of copper-nickel-tin alloy.The accuracy of the parameters was verified by the comparison of tensile simulation and test.Further analysis shows that f₀ flow stressstrain curve of Cu-6Ni-6Sn alloy is almost not affected,and the increase of fN and fC will cause the peak point and failure point to move forward,while the increase of f_F will cause the failure point to move forward.Finally,through the analysis of damage evolution and equivalent strain distribution in the process of tensile simulation,it is concluded that the material damage parameters have a positive correlation with the processing temperature.（3）Based on the modified GTN damage model,the mold model required for oblique rolling perforation was constructed by using Deform finite element simulation software,and the processing process parameter scheme was designed,and the numerical simulation of diagonal rolling perforation was carried out on Φ50mm× 150mm Cu-6Ni-6Sn alloy,focusing on the changes of stress,strain,temperature field and force energy data of billet in the oblique rolling perforation process.The influence of process parameters such as processing temperature,hole diameter and head on pipe forming was thoroughly studied,and finally the reasonable process parameters were selected between 700℃ and 750℃.The radial pressure reaches 10%14%;The forward extension is controlled at 20mm.The finite element analysis results can provide a reference for the formulation of experimental protocols.