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对比研究成分为20MnSiV和16MnVNb的HRB400钢筋的屈服行为,在同一轧制工艺条件下,与含钒钢筋相比,含铌钢筋应力-应变曲线没有明显的屈服平台。对试验钢的化学成分、显微硬度进行测试分析,利用光学显微镜、扫描电镜和透射电镜对试验钢的微观组织进行观察。结果表明,20MnSiV试验钢组织主要为铁素体+珠光体组织,16MnVNb的组织为等轴状铁素体+珠光体+针状铁素体,其中针状铁素体周围珠光体退化明显。针状铁素体的显微硬度介于珠光体与铁素体之间,其内部存在高密度位错。针状铁素体组织的大量存在是导致含铌HRB400钢筋无屈服平台的原因。
Compared with the yield behavior of HRB400 steel with 20MnSiV and 16MnVNb, the stress-strain curve of Nb-containing steel does not have obvious yield platform under the same rolling conditions compared with vanadium-containing steel. The chemical composition and microhardness of the test steel were tested and analyzed. The microstructure of the test steel was observed by optical microscope, scanning electron microscope and transmission electron microscope. The results show that the microstructure of 20MnSiV steel is mainly ferrite + pearlite, and the microstructure of 16MnVNb is equiaxed ferrite + pearlite + acicular ferrite. The degeneration of acicular pearlite is obvious. Acicular ferrite microhardness between the pearlite and ferrite, its internal high-density dislocations. The presence of acicular ferrite in large numbers is responsible for the yieldless platform of the niobium-containing HRB400 steel.