摘要
乏燃料后处理是核燃料循环后段的关键环节,也是核反应堆中卸出乏燃料较为常见的处理方式,但传统耐蚀不锈钢难以满足长期高温、浓硝酸溶液和高辐射环境条件下的使用要求。本文针对乏燃料后处理设备用新型耐高浓度沸腾硝酸腐蚀的Ti35合金,采用斜轧穿孔+热轧+冷轧+机加工工艺路线,生产规格为Ф375 mm×10 mm×L mm(L,长度根据坯料及使用需求确定)的成品Ti35无缝管材,并对其取样进行二次大气热处理,旨在研究二次热处理对管材组织及室温力学性能的影响,掌握管材组织与性能之间的匹配关系。结果表明:当冷轧态管材经过630℃×150 min/空冷(AC)成品热处理后,管材的显微组织由拉长α晶粒和少量等轴晶粒组成,为单相混合组织;经二次热处理500℃×150 min/AC后,管材显微组织中的等轴α晶粒相对于成品热处理有所增加,但增幅不明显,室温力学性能也未发生明显变化;当二次热处理温度从500℃逐步升至760℃时,等轴晶粒α相明显长大,室温抗拉强度逐渐减小,延伸率逐渐增大;提高至870℃时,显微组织中有强化片层相析出,室温抗拉强度显著增大,断裂延伸率降低。管材抗拉强度总体呈现先降低后升高的趋势,且均满足应用要求。该结果说明,Ti35合金经成品热处理和二次热处理,均可获得力学性能和塑性匹配良好的成品管材,同时表明在Ti35合金生产过程中延长成品热处理时间或者进行二次热处理,对管材的力学性能影响不大。
Spent fuel reprocessing is one of the most critical stages in the nuclear fuel cycle and is the most widely used method for han⁃dling spent fuel from nuclear reactors.Traditional corrosion-resistant stainless steel can no longer meet the requirements for long-term use under high temperature,concentrated nitric acid solution,and high radiation conditions.This study focused on a new type of Ti35 alloy that was specially used for post-processing equipment.Rotary piercing,hot rolling,cold rolling,and mechanical machining were used to fabricate Ti35 alloy seamless tubes with a specification ofФ375 mm×10 mm×L mm(L stands for length which is determined ac⁃cording to the billet material and the usage requirements).The effect of secondary heat treatment on the microstructure and mechanical properties was studied.The results showed that after final heat treatment at 630℃×150 min and air cooling(AC),microstructure of Ti35 tubular product was composed of a singleαphase consisting of mixed grains with elongated shape and a small amount of equiaxed shape.After secondary heat treatment at 500℃×150 min and AC,an increase in equiaxedαgrains was found but not significant com⁃pared to the finished Ti35 tube,and there was no obvious change in the mechanical properties.When increased from 500 to 760℃,the equiaxedαgrains grew significantly,the strength gradually decreased while the elongation gradually increases.While the secondary heat treatment increased to 870℃,little amount of layered strengthening phase precipitated in the microstructure,resulting in in⁃creased strength and decreased plongation.The overall strength of Ti35 tubes showed a trend of decreasing before increasing,and all of the values met the requirement.This result indicated that both final heat treatment and secondary heat treatment equipped tubes with good mechanical properties,meaning that secondary heat treatment or extended processing time of final heat treatment had little effect on the mechanical properties of the tubes.
作者
姬坤海
张辉
杨帆
吴金平
张鹏飞
张国君
JI Kunhai;ZHANG Hui;YANG Fan;WU Jinping;ZHANG Pengfei;ZHANG Guojun(Department of Materials Science and Engineering,Xi’an University of Technology,Xi’an 710048,China;Xi’an Rare Metal Materials Institute Co.,Ltd.,Xi’an 710016,China)
出处
《铜业工程》
2025年第4期81-87,共7页
Copper Engineering
基金
陕西省重点研发计划项目(2024GX-YBXM-227,2024GX-YBXM-358)
秦创原引用高层次创新创业人才项目(QCYRCXM-2022-290)资助。
关键词
Ti35合金管材
二次热处理
显微组织
力学性能
Ti35 alloy tube
secondary heat treatment
microstructure
mechanical properties
作者简介
姬坤海(1987-),男,陕西西安人,博士,高级工程师,研究方向:稀有金属材料加工,E-mail:jikunhai@126.com;通信作者:张辉,工程师,E-mail:zhang_630224@163.com。
