Abstract

One of the most efficient and cheapest ways to improve steel reinforcement bars is the Tempcore process. In this study, the effects of water pressure, water temperature, bar diameter, and its initial temperature, as Tempcore process parameters on microstructural and mechanical properties of reinforcing rebars were numerical and experimental investigated by using the Taguchi experimental design method. Results showed that these Tempcore process parameters influence the cooling intensity, which causes the formation of martensite at the surface layer and fine-grained ferrite–pearlite at the core and improvement of tensile strength. All of the considered parameters strongly affect the volume fraction of ferrite and pearlite in the rebar center and thickness of the martensite layer, but among them, water pressure with a 59% impact has a more substantial effect. Ultimately, to figure out the mechanical characteristics of hot rolled and optimal sample’ rebar, tensile tests were conducted. Outcomes displayed that the Tempcore process increases the yield and ultimate tensile strengths as much as 1.5 and 1.3 times, respectively, but slightly decreases the elongation.

Graphic Abstract

中文翻译：

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Tempcore工艺参数对双相钢筋的组织演变和力学性能影响的实验和数值研究

摘要

Tempcore工艺是改进钢筋的最有效，最便宜的方法之一。在这项研究中，水压力，水温，棒材直径及其初始温度（作为Tempcore工艺参数）对钢筋的微结构和力学性能的影响进行了数值模拟，并使用Taguchi实验设计方法进行了实验研究。结果表明，这些Tempcore工艺参数会影响冷却强度，这会导致表层形成马氏体，并在芯层形成细晶粒铁素体-珠光体，并提高拉伸强度。所有考虑的参数都强烈影响钢筋中心的铁素体和珠光体的体积分数以及马氏体层的厚度，但其中，水压的影响为59％，效果更显着。最终，为了找出热轧和最佳样品钢筋的机械特性，进行了拉伸试验。结果表明，Tempcore工艺可将屈服强度和极限抗拉强度分别提高1.5倍和1.3倍，但伸长率却略有降低。

图形摘要