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采用Nb-Cr微合金化控冷工艺进行准25 mmⅢ级带肋钢筋工业生产试验,对实验钢筋的生产工艺、化学成分、力学性能及金相组织进行了分析。结果表明,Nb-Cr微合金化控制冷却生产的Ⅲ级带肋钢筋的金相组织为表层回火S、心部F+P,F的晶粒度为9.0～9.5级,并且P量较多,实验钢筋屈服强度、抗拉强度和断后伸长率分别比标准要求高65 MPa、70 MPa和6.5%。在此基础上对Ⅲ级带肋钢筋进行成分优化,降低合金元素Mn、Cr、Nb的含量,成分优化后钢筋力学性能符合Ⅲ级带肋钢筋标准,达到了降低生产成本的目的。
The Nb-Cr microalloyed controlled cooling process was used to carry out the industrial production test of quasi-25 mm Ⅲ grade ribbed steel bars. The production process, chemical composition, mechanical properties and microstructure of the experimental steel bars were analyzed. The results show that the microstructure of grade Ⅲ ribbed steel produced by controlled cooling of Nb-Cr microalloying is surface tempering S. The grain size of F + P and F in core is 9.0-9.5, and the amount of P is more The yield strength, tensile strength and elongation at break of experimental steel were respectively 65 MPa, 70 MPa and 6.5% higher than the standard requirements. On the basis of this, the composition of Grade Ⅲ ribbed steel bars is optimized and the contents of Mn, Cr and Nb alloying elements are reduced. The mechanical properties of steel bars after optimization are in accordance with the standards of Grade Ⅲ ribbed steel bars, and the production cost is reduced.