Improvement of mechanical properties of reinforcing steel used in the reinforced concrete structures

Abstract

SAEIOIO structural carbon steel, which has a low cost price and wide range of use in the construction industry, has been studied as dual phase (DP) steel subjected to appropriate heat treatment, and its mechanical properties have been investigated under various tempering conditions. Intercritical annealing heat treatment has been applied to the reinforcing steel in order to obtain DP steels with different martensite volume fraction. In addition, these DP steels have been tempered at 200, 300 and 400 'C for 45 min and then cooled to the room temperature. Mechanical properties such as tensile strength, yield strength, reduction in cross-sectional area, total elongation, resilience modulus and toughness have been examined. Furthermore, fractographic examination has been done with scanning electron microscope (SEM) as well as metallographic examination of the steels. As a result of this study, it is found that mechanical properties of DP steel have changed according to the hardness and ratio of martensite phase. In addition, tensile strength, yield strength and resilience modulus of the steels have been reduced. In contrast, the total elongation, reduction of the cross-sectional area and toughness have been increased.

A Finite Element Method for the Prediction of Thermal, Metallurgical, and Mechanical Behavior of Rebars in the TempCore Process

“…In rebar produced by this method, the microstructure, and hence the mechanical properties, continuously varies from the surface to the centre of the rebar. The overall yield strength of the rebar depends on the volume fraction of the individual phases present and is, therefore, in turn dependent on the process parameters, the most important being the water flow rate, the quenching time (rebar finishing speed), the finishing temperature, and the steel chemical composition …”

Tensile strength and oxide analysis of carbon steel in concrete exposed in atmospheric environment for 53 years

“…The tensile stress-strain curve of the rebar (without concrete cover layer) was obtained using a universal testing machine (LETRY Machine Company, Xi'an, China) with a strain rate of 1 mm・min -1 [15] . Subsequently, the fracture surface of the tensile test sample was investigated with a ZEISS SUPRA 55 SAPPHIRE (Carl Zeiss AG, Germany) scanning electron microscope.…”

“…In the Raman test, the source used for excitation was an argon ion laser with a wavelength of 514.5 nm, and an area with a diameter of 2 μm was chosen for analysis, the excitation laser power on the sample was chosen at 0.47 mW [2,4] . The prepared samples were etched in alcohol with 2% nitric acid [15] . The microstructure of the substrate was observed with a Batuo BMM-100 (Batuo Instrument Co., Ltd, Shanghai, China) optical microscope system.…”

The Effect of Carbon Content in Martensite on the Strength of Dual Phase Steel

“…The dual phase heat treatment can be applied to low-carbon steels with carbon content higher than 0.1% and to specimens which have sections larger than 1.0 mm [5]. Dual phase steels are identified as a class of HSLA steels designated by a composite microstructure constituted by hard martensite phase dispersed in the soft ferrite matrix.…”