The Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8) mandates a specimen gauge reduction for obtaining the tensile properties of reinforcing steel bars. The standard outlines the specimen preparation requirements and methods to ensure that test results well represent the material properties. On the other hand, some codes differ regarding the approach to specimen preparation. They do not apply gauging, for both deformed and plain steel bars. Thus, the effect of specimen gauge reduction on the tensile properties of reinforcing steel bars was evaluated, and the interconnection of properties to the layer hardness was analysed. The experiment governed a range of deformed hot-rolled bar sizes, tested in tension using precision instruments. The Rockwell hardness test was implemented layerwise on the specimen’s cross section, and the hardness number (HRC) was measured as a function of the layer distance to the centre. A finite element model was constructed to study the stress concentrations induced by a constant indentation, simulating the HRCs, and to numerically construct the stress–strain relationship of ungauged steel bars based on the core properties and the section HRC relationship. Scanning electron microscopy readings were performed to visually and chemically justify the results. It was shown that the specimen gauge reduction significantly influenced the resulting stress–strain behaviour of the material, and the yield and ultimate strengths were reduced. It was also demonstrated that the hardness response is proportional to the distance to the specimen’s axes. The corresponding yield and ultimate strengths thus increased accordingly, from the inner to the outer layers of the bar. Testing a gauged specimen will therefore result in lower strength than that of an ungauged steel bar.

该金属材料的拉伸试验的标准测试方法（ASTM E8）要求减少标本规格以获得钢筋的拉伸性能。该标准概述了样品制备要求和方法，以确保测试结果能很好地代表材料的性能。另一方面，一些代码在标本制备方法上有所不同。对于变形钢筋和普通钢筋，它们均不适用测量。因此，评估了减少试样规格对钢筋的拉伸性能的影响，并且分析了性能与层硬度的相互关系。实验控制了一系列变形的热轧棒材尺寸，并使用精密仪器进行了拉力测试。洛氏硬度测试是在样品的横截面上逐层进行的，并测量硬度值（HRC）作为层到中心的距离的函数。构造了一个有限元模型来研究恒定压痕引起的应力集中，模拟HRC，并根据芯的性质和截面HRC关系以数值方式构造未固结钢筋的应力-应变关系。进行扫描电子显微镜读数以目视和化学证明结果。结果表明，试样规的减少显着影响了材料的应力应变行为，屈服强度和极限强度降低了。还证明了硬度响应与到试样轴线的距离成正比。因此，相应的屈服强度和极限强度相应提高，从棒的内层到外层 因此，测试标定的样本将导致强度低于未测量的钢筋。