INFLUENCE OF INTERCRITICAL ANNEALING TEMPERATURE ON  MECHANICAL PROPERTIES AND MICROSTRUCTURE OF  0.23%C LOW ALLOY STEEL

SC Ikpeseni; BO Onyekpe; H Ovri

doi:10.4314/njt.343.968

INFLUENCE OF INTERCRITICAL ANNEALING TEMPERATURE ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF 0.23%C LOW ALLOY STEEL

Authors

SC Ikpeseni DEPARTMENT OF MECHANICAL ENGINEERING, DELTA STATE UNIVERSITY, OLEH CAMPUS, DELTA STATE. NIGERIA.
BO Onyekpe DEPARTMENT OF MECHANICAL ENGINEERING, UNIVERSITY OF BENIN, BENIN-CITY, EDO STATE. NIGERIA.
H Ovri INSTITUTE OF MATERIALS RESEARCH, MATERIALS MECHANICS, HELMHOLTZ-ZENTRUM GEESTHACHT ZENTRUM FÜR MATERIAL- UND KÜSTENFORSCHUNG, MAX-PLANCK-STRAßE 1, 21502 GEESTHACHT, GERMANY.

DOI:

https://doi.org/10.4314/njt.343.968

Keywords:

intercritical annealing, dual phase steel, mechanical properties, microstructure

Abstract

The influence of intercritical annealing temperature on the microstructure and mechanical properties of an 0.23%C low alloy steel was undertaken in this work. The as-received steel was normalised and afterwards annealed in the (?+?) region at 730^OC, 750^OC, 770^OC and 790^OC followed by quenching in hot water at about 50^OC.Mechanical testing (tensile, impact and hardness) of the annealed samples were conducted at room temperature. The fracture surfaces of the impact test samples were examined using the scanning electron microscope (SEM). Micros structural evolution of the samples was also examined with an optical microscope. The results showed that all the evaluated mechanical properties were improved by intercritical annealing, with the samples treated at 790^OC possessing the optimum combination of properties. The ultimate tensile strength (UTS), yield strength (YS), impact strength (IS), total elongation (TEL) and hardness of these samples improved by 2.7%, 13.7%, 19.7% and 31.05% respectively over the normalised sample. The microstructure photographs of the intercritically annealed samples revealed duplex structures of predominantly martensite in a ferrite matrix with little dispersions of either carbide or retained austenite, which is a typical characteristic of conventional dual phase steel.

http://dx.doi.org/10.4314/njt.v34i3.11

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Issue

Vol. 34 No. 3 (2015)

Section

Chemical, Industrial, Materials, Mechanical, Metallurgical, Petroleum & Production Engineering

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How to Cite

INFLUENCE OF INTERCRITICAL ANNEALING TEMPERATURE ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF 0.23%C LOW ALLOY STEEL. (2015). Nigerian Journal of Technology, 34(3), 499-505. https://doi.org/10.4314/njt.343.968