Coupling Thermo-mechancial And Microstructure Analysis Of Super Diameter Shell In Hot Forming Process

The hot rolling Super Diameter Shell(SDS) is an advanced plastic forming techniquefor manufacturing large seamless shell ring, which is used in production of large pressurevessel. And its products have been widely applied in many industry fields, such asAeronautics and Astronautics, petroleum-chemical industry, atomic energy etc. It is greatsignificance that the hot rolling SDS will promote further application and development onits hot forming process in our country. Studies section of the hot forming for the SDS is asfollows:First of all, the thermal properties parameters of the austenitic stainless steel0Cr18Ni9Ti are obtained by simulation with the hlep of software-Jmatpro. Besides,considering several impact factors of the deformation temperature and strain rate, the flowstress constitutive model of0Cr18Ni9Ti were acquired by the experiment, in which themodel is compressed on thermal modeling test machine.In the next place, proprietary the finite element software program DEFORM is usedto develop a two-dimensional rigid-viscoplastic finite element model, a coupledsimulation of deformation with heat transfer and microstructural evolution has beencarried out for the SDS hot forming. The research results indicate that the shell ’sdeformation extent form the local small regional to the noodle layers of the arc andcylinder inside in the plastic deformation region of the SDS, and the deformation of innerand outer layer region is gradually extended to the region of the intermediate layer; itstemperature fields trun on zonal distribution, the high temperature zone locate in place ofits interlayer region, and the low temperature zone locate in place of its inner and outerlayer regional; its internal microstructure distribution also trun on zonal distribution, andits average grain size have good refining effect in an outer layer and an inner layer region,rolling force represent a periodic distribution.Besides, there are several main rollingprocess parameters, such as the feed speed of driving roller, friction factor, the initialtemperature and the thickness of the shell blank, it make further research on the influencelaw of the rolling craft parameters on what is deformation filed, temperature filed rolling force and microstructure evolution. The results have been presented that, first, moderatelyincreasing the driving roller’s speed of can make enlargement of rolling force and havemore uniform distribution in temperature field and microstructure; second, if the factionfactor between shell and roller is adjusted appropriately, it will have correspondinginfluence on uniform distribution of temperature; accompanied by rolling force to reducein the initial shell temperature rising, and under proper temperature can also have betteruniform distribution of microstructure and more fine of grain in formed SDS; The thickerinitial shell thickness leads to greater rolling force, and that can also makes more unevendistribution of deformation and temperature filed, however, the formed SDS can obtainbetter microstructure distribution and more fine grain. Thus it is able to optimize thedesign of the rolling process parameters.In the end, finite element simulation results are obtained during the SDS hot rollingprocess with multiple sets of rolling craft parameters, including deformation, temperature,rolling force and microstructure evolution. The parameters and results are used to train thetrain Back Propagation Network, what is Back Propagation Network, and finally thenetwork modal is acquired, which can predict thermal-mechanical-microstructure varyingcondition during hot forming of the SDS.