Study On Microstructure And Texture Of The Domestic New Zirconium Alloys Tube During Cold Rolling

The microstructure of zirconium alloys, especially the second phase particles(SPPs), such as the size, distribution and kind of that, have a profound influence onboth corrosion-resistance and mechanical ability. In addition, textures, which couldexert effects on the hydride orientation, mechanical properties, irradiation growth andcorrosion-resistance properties, are formed during the fabrication processes ofzirconium alloys. So it is important to investigate the microstructure, SPPs and textureof the domestic new zirconium alloys tube during cold rolling. In order to provide richexperiment data for localization work of the new zirconium alloys tubes, and to shedsome light on optimizing the existing manufacturing process.In this thesis, the evolution of microstructure, SPPs and texture of domesticZr-Sn-Nb-Fe tube during cold rolling was investigated using Electron channelingcontrast (ECC), Secondary electron (SE) imaging, electron backscatter diffraction(EBSD) and X-ray diffraction (XRD) techniques.The investigation results showed that:①The grain of first annealing materials isequiaxed, and size ranges of all the grains below10μm. Grains are elongated in theaxial direction (AD) after cold deformation. The main observation on the pilgeredstructures can be stated in a single point to be ‘heterogeneous deformation’, a fewequiaxed grains were observed, albeit to a lesser extent, even after50%reductionduring first cold rolling. There are similar microstructure during second cold rolling.②The shape of SPPs in zirconium alloy tube is sphere, ellipsoid or clavate. Thoseparticles are not destructible during the cold rolling process. The distribution of SPPsduring first cold rolling is banding along AD, however, is homogeneous during secondrolling.③The statistical results by means of quantitative metallography show thatthe average size of SPPs is a bit lower than80nm after first cold rolling and theparticles mainly concentrated on the range from10nm to50nm. However, the averagesize of SPPs is higher than80nm after second cold rolling and the particles mainlyconcentrated on the range from50nm to100nm.④The investigation of evolution ofmacro-texture showed that the basal poles of annealing tube align in the tangentialdirection with a split of the basal pole maxima of certain angle (±20-40°), tilted fromthe tangential direction (TD) toward the radial direction (RD). The texture keeps stableduing the followed first cold rolling. It is similar to the basal poles of tube duing the whole second cold rolling, even after80%reduction. a <11(?)0> direction of grainparallel to the axial direction (AD) during annealing, but the basal planes rotatecontinuously by±30°around their poles during cold rolling, so that in the final stableposition, instead of the <11(?)0> direction, the <101ˉ0> direction of grain becomesparallel to the axial direction (AD).⑤The investigation of evolution of micro-textureshowed that it is similar to the results of macro-texture. The basal poles of all samplesalign in the tangential direction (TD) with a split of the basal pole maxima of certainangle (±20~40°), tilted from the tangential direction (TD) toward the radial direction(RD), and the results of orientation factor prove it.