Microstructure Evolution Of High Neck Flange Forming With Closed Ring Rolling Technology

The high neck flange is one of the key component to the pipe connection parts, it has theeffect of transfer pipeline working pressure.High neck flange manufacturing technologylevel directly affect the development progress on fittings.As aviation, aerospace, machinery,transportation, energy and other industrial fields demand for of a large number of circularpieces industrial areas, such as processing products in addition to meet the requirements ofshape and size,also need more excellent internal microstructure to meet the needs of thepractical use to ensure the safety, reliability, in the process of use.This paper based on highneck flange forming with closed ring rolling technology,to study the law of microstructureevolution in the process of forming.Based on the volume of metal plastic deformation invariance principle, and build themacro-micro finite element model of high-neck flange forming with closed ring rolling inDEFORM software. Secondary development of40Cr steel material microstructure evolutioncomputation model integration in the finite element calculation model,simulation of heattransfer, the deformation and microstructure evolution in a closed rolling process.Throughfinite element simulation, we obtained the stress field, strain field and temperature fieldchange rule which laid a foundation for carrying out a research into the microstructure.The study found that the flange blank metal deformation characteristics are tensile ontwo directions and compression on one direction,the same as the axial and circumferentialtensile, radial compression.In the process of rolling at about1100℃temperature range,thetop of the flange neck temperature to reduce the most obvious.In the whole rolling process,the dynamic recrystallization and recrystallization volume fraction changes started withflanged chassis of outer diameter to expand the middle part of the chassis,the axial directionfrom chassis to neck extension.Flange products final grain size changes mainly depends onthe size of dynamic recrystallization occur ratio, at the same time in the process of rollingalso occurred static recrystallization and meta-dynamic recrystallization. Among the many factors of high neck flange forming with closed ring rolling, the driveroller speed, idle roller feeding speed and initial temperature have a significant effect on thedynamic recrystallization volume, dynamic recrystallization grain size, recrystallizationvolume fraction and average grain size. Study identified that drive roller speed with8rad/sand idle roller feeding speed between1.2to1.5mm/s, the flange products overall grain sizedistribution is more uniform, and appropriately increase the value of both favorable dynamicrecrystallization occurs.In this paper, the research results in the high neck flange forming process parametersoptimization and product forming quality control have provided the basis in theory andsimulation,and laid a solid foundation for rolling complex section annular parts.