低成本含铌抗震钢筋生产工艺控制  

Technology control of low cost niobium containing seismic reinforced bar

作　　者：马正洪 朱伟娟 曹磊[1] 王哲 黄沁 MA Zhenghong;ZHU Weijuan;CAO Lei;WANG Zhe;HUANG Qin(Jiangsu Yonggang Group Co.,Ltd.,Zhangjiagang 215628,China)

机构地区：[1]江苏永钢集团有限公司,江苏张家港215628

出　　处：《轧钢》2022年第3期128-132,共5页Steel Rolling

基　　金：中信金属宁波能源有限公司资助项目(2019530101000573);江苏永钢集团有限公司资助项目(2020530101000951)。

摘　　要：为降低生产成本,江苏永钢集团有限公司采用Nb微合金化试制了HRB400E钢筋。以φ16 mm HRB400E钢筋为例,针对钢筋无屈服现象问题,对3种不同Nb含量钢筋的显微组织、析出物尺寸和分布、室温拉伸应力-应变曲线进行了分析。结果表明:由于含Nb量较高的钢筋其固溶Nb量较多,同时由于精轧区域为升温轧制,尤其是小规格钢筋采用切分轧制工艺,终轧温度较高,降低了相变点温度,再加上小规格钢筋在冷床上的冷速较快,使其容易产生针状铁素体、贝氏体等低温异常组织,导致其无屈服现象。为此,对钢筋Nb含量及生产工艺进行了优化:将钢筋中Nb质量分数从0.035%减少到0.01%;铸坯加热温度控制为1100~1150℃;保证开轧温度为1050~1080℃、精轧入口温度为950~1000℃、终轧温度为1000~1050℃,以降低终轧后钢筋固溶Nb含量;上冷床温度控制为880~920℃,并在冷床上增加可调节的保温装置,对钢筋进行轧后缓冷,以延长珠光体转变时间,这是防止小规格钢筋冷速过快导致针状铁素体、贝氏体组织过多的关键技术。生产实践表明:上述工艺措施可有效避免钢筋出现针状铁素体、贝氏体组织,屈服平台不明显比例从0.51%降至0,解决了小规格含Nb钢筋屈服不明显的问题,降低了含Nb抗震钢筋的生产成本。In order to reduce the production cost, HRB400E reinforced bar was trial-produced by using Nb microalloying in Jiangsu Yongsteel Group Co., Ltd.Taking φ16 mm HRB400E reinforced bar as an example, the microstructure, precipitate size and distribution, and tensile stress-strain curves at room temperature of three kinds of reinforced bars with different Nb contents were analyzed for the no yield phenomenon.The results show that the reinfored bars higher Nb content has mole Nb in solid solution. Because the finishing rolling area is heat rolling, especially the small gauge reinforced bars are used splitting rolling process, the finishing temperature is higher, and the phase transition temperature is reduced. Meanwhile, the cooling rate is faster of small gauges on the cooling bed, making it easy to generate low temperature abnormal microstrecture of acicular ferrite, bainite, resulting in no yield phenomenon.Therefore, the Nb content of reinforced bar and the production processes were optimized. The Nb content of bar was reduced from 0.035% to 0.01%,and the heating temperature of the billet was controlled in the range of 1 100-1 150 ℃. In order to reduce the Nb content of solid solution after finishing rolling, the starting rolling temperature, finishing inlet temperature and finishing rolling temperature were ensured to be 1 050-1 080 ℃, 950-1 000 ℃ and 1 000-1 050 ℃, respectively. The temperature of bar entering cooling bed was controlled to be 880-920 ℃, and an adjustable heat preservation device was added to the cold bed. The bar was cooled slowly after rolling to prolong the pearlite transformation time, which was the key technology to prevent the too much aciculate ferrite and bainite structure of small gauge bar caused by cooling fast. The production practice show that the above technological measures can effectively avoid the acicular-ferrite and bainite structure of the reinforced bar, and the proportion of the yield platform which is not obvious is decreased from 0.51% to 0, which solves the prob

关 键 词：含Nb钢筋 屈服平台 控轧控冷 工艺优化 NB含量 低成本 

分 类 号：TG335.64[金属学及工艺—金属压力加工]