矫直工艺对Zr-Sn-Nb系合金管材氢化物取向的影响

核反应堆包壳管的氢化物取向因子会较大程度的影响其力学性能和使用性能。为此,使用6辊精密管材矫直机对?10 mm的Zr-Sn-Nb系合金成品管材进行矫直实验,研究辊缝值、弯曲量及矫直辊角度对其氢化物取向因子的影响。采用X射线衍射技术分析矫直管材的残余应力,采用光学显微镜观察高压釜渗氢试样的氢化物分布,并通过评级软件检测氢化物取向因子(Fn~(40°))。结果表明:辊缝值、弯曲量及矫直辊角度均对矫直后管材的残余应力有显著影响,并且管材氢化物取向因子随着残余应力的增大而增大。当辊缝值≥10 mm,弯曲量≤4.2 mm,矫直辊角度在31.5°～33.5°之间时管材残余正应力≤35.6 MPa,切应力≤37.8 MPa,此时氢化物取向呈周向或接近周向,氢化物取向因子满足技术要求。

Effect of Straightening Process on Hydride Orientation of Zr-Sn-Nb Alloy Tube

The hydride orientation factor has great influence on the mechanical properties and service performance of the fuel cladding tube during the nuclear reactor operation. The straightening experiment was carried out by using 6-roll precision tube straightener, the influence of roll gap, bending and straightening roller angle on the hydride orientation of Zr-Sn-Nb alloy pipe with ?10 mm was studied. The residual stress of the straightened sample was analyzed by X-ray diffraction technique, the hydride distribution of autoclave hydrogenated samples was observed by optical microscope, the hydride orientation factor(Fn~(40°))was detected by rating software. The results show that roll gap, bending and angle of straightening roller have significant influence on the residual stress of pipe after straightening, the hydride orientation factor increases with the increase of residual stress. When the roll gap is greater than or equal to 10 mm, the bending less than or equal to 4.2 mm,and the angle of straightening roller is between 31.5°and 33.5°, the residual normal stress is less than or equal to 35.6 MPa, shearing stress is less than or equal to 37.8 MPa. The hydride orientation is circumferential or near circumferential, hydride orientation factor to meet the technical requirements.