ANALYSING THE EFFECT OF THERMAL TREATMENT WITH AN AID OF BRINE QUENCHING ON MICROSTRUCTURAL CHARACTERISTICS AND PHYSICAL PROPERTIES OF AISI-304 PLATES

Abstract

In this work, the effects of brine quenching on the mechanical properties and microstructural attributes of AISI 304 steel have been analysed. For a reference purpose, one sample was kept in ‘as-received’ condition. Three steel plates were treated at 800oC for 1 hour, 1.5 hour and 2 hours respectively. The heated samples were cooled inside brine solution up to room temperature. For mechanical property analysis, all the four plates were cut into standard sized specimens for tensile test, hardness test and toughness test. The microstructural analysis reveals that pitting corrosion has affected the γ-grains as well as δ-boundaries. The ‘as-received’ samples have shown the highest value of ultimate tensile strength (UTS) i.e., 940 MPa with 59.5% of elongation whereas the third heat treated sample, which was heated for 2 hours, has shown a decrement of 13% and 55% in UTS and elongation respectively as compared to these of ‘as received’ sample. As a result of Cr-deterioration and carbide dissolution at grain boundaries, an increase in hardness was recorded in the heat-treated samples. Also, the lowest toughness, 35% lower than as received sample, was recorded in the third sample which are heated for a long period.