Effect of heat treatment on the pearlitic structure of steel

• Main Author: Yap, Jonathan Boon Kwang.
• Other Authors: Oh Joo Tien
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/15604
• Institution: Nanyang Technological University

The aim of this project is to study the effect of heat treatment on steel as well as the effect in relation to the amount of carbon. Samples of 0.77 and 1 percent carbon in iron were put into an oven and heated from intervals of 4 to 48 hours. The use of Scanning Electron Microscope (SEM) micrographs substantiates the pearlitic structural change to a spheriodised structure. This report details the change in inter-lamellar spacing and will note the concurrent change of pearlite to spheroidite as observed in the experiment. Henceforth, by detailing the changes in inter-lamellar spacing, it is found that the interlamellar spacing increases with heat treatment. This increase stimulates the diffusional growth of the pearlitic lamellar structure which in turn, promotes the coalescence of spheroids from the lamellar plates. Spheriodisation commences at about 16 hours at a temperature of 700 º C, this can be attributed to the preference for a reduced surface energy state concurrent with the 2nd law of thermodynamics. The rate of spheriodisation is reduced with increasing inter-lamellar spacing.