Title : VARIATIONS IN MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THERMO-MECHANICALLY-TREATED (TMT) STEEL REINFORCEMENT BARS
Authors : Sooraj A.O. Nair, Gokul P.R., Sethuraj R., Sarvani Nandipati, Radhakrishna G. Pillai
Publication : 8 - 10, October 2015
Volume : 1
Pages :
Price : 250
Abstract : Thermo-Mechanically-Treated (TMT) or Quenched-and-Self-Tempered (QST) steel bars are extensively used for reinforced concrete construction in India. The unique microstructure (say, with a hard periphery and a soft/ductile core) helps in providing sufficient surface hardness and ductility. To ensure quality construction, the distribution of tempered martensite and ferrite-pearlite in the cross-sectional area should be concentric and uniform and the variations in the yield strength and elongation should be reasonable. In this study, four commercially available TMT steel rebars were evaluated for their microstructure, yield strength, and ductility. Multiple specimens of 500D Grade TMT/QST bars with 8, 12, and 16 mm diameter were evaluated. The results show significant variations in the microstructure features (i.e., the distribution of martensite and pearlite-ferrite regions) and the mechanical properties (i.e., yield strength, tensile strength, and elongation/ductility). These indicate that there is a dire need to amend the existing IS 1786 (2008) specifications to ensure better quality TMT/QST steel products.