Image J Analysis of Six Different Annealed Temperatures of 0.17% C of HSLA Steels

Annealing is a heat treatment procedure in which the mechanical properties of a material are being altered, and such alterations cause changes in its properties such as strength and hardness. It is usually carried out to improve ductility and toughness, to reduce hardness and to remove carbides. This study deals with the use of image analysis processing method for the measurement of structure of six annealed samples of 0.17% High Strength Low Alloy (HSLA) Steels (840°C - 990°C) with 30°C interval and 30 minutes soaking time. From the optical microscope images using Image J program, some parameters like calculation of area, pixel value statistics, distances and angles measurements, edge detection, such as the circularity, ferret angle, solidity and perimeter, average area and the percentage area were examined. The annealed sample of 960°C gave the highest grain count of 543 with a perimeter of 41.518; standard deviation 7.057 and a mean of 28.722 which shows that annealing greatly improved the fatigue life of the steel. From the mechanical analysis result, the annealed sample at 840°C has a highest hardness value of 129.4 BHN and gave the lowest impact value of 58.75 J. This study shows a significant decrease in the hardness value as the annealing temperature increased which signifies that annealing temperature enhanced the fatigue property and tensile strength (wear strength) of the steel in study.