Effect of Thermomechanical Treatment on Microstructure and Mechanical Properties of ASTM A615/A615M Grade-60 Steel Reinforcement Bars

Syed Ali Afzal; Subhan Jogi; Tufail Ahmed; Abdul Qadir; Vinod Kumar; Zubair Laghari

Syed Ali Afzal Department of Metallurgy and Materials Engineering, Dawood University of Engineering and Technology, Karachi, Pakistan
Subhan Jogi Department of Metallurgy and Materials Engineering, Dawood University of Engineering and Technology, Karachi, Pakistan
Tufail Ahmed Department of Metallurgy and Materials Engineering, Dawood University of Engineering and Technology, Karachi, Pakistan
Abdul Qadir Department of Metallurgy and Materials Engineering, Dawood University of Engineering and Technology, Karachi, Pakistan
Vinod Kumar Department of Metallurgy and Materials Engineering, Dawood University of Engineering and Technology, Karachi, Pakistan
Zubair Laghari Department of Metallurgy and Materials Engineering, Dawood University of Engineering and Technology, Karachi, Pakistan

Keywords: hot rolling, thermomechanical treatment, reinforcement bars, tempered martensite, pearlite

Abstract

The purpose of this research is to manufacture steel rebars per the obligations declared in ASTM A615/615M Grade-60 via hot rolling of steel billets and thermomechanical treatment process installed at the manufacturing facility. Afterward, to understand the effect of processing parameters on the microstructure and mechanical properties of the finished product. The characterization of rebars include the chemical analysis of the final product. Moreover, the average yield strength, ultimate tensile strength, yield strength and ductility were examined. Furthermore, 180° bend testing, Charpy V-notch test, hardness, scanning electron microscopy (SEM) and optical microscopy were also explored. The results show the product perfectly endorses the demand of the standard and the values are within the specified range. But the material demonstrates menial impact energy and the characteristic features of the brittle fracture. Furthermore, hardness testing, optical microscopy and SEM corroborate the existence of dissimilar microstructures in the vicinity of core and case areas. The results shows the material satisfy the ASTM A615/615M grade-60 standard, but exhibit inferior energy absorption capabilities.