Effect of Isothermal Annealing on Microstructure and Mechanical Properties of a High Carbon Steel
Serdar Kuzkaya Yakup Yurekturk Faiz Muhaffel Murat Baydogan
AbstractIn this study, isothermal annealing was performed to C70 quality steel sheet in a salt bath at 250 °C and 350 °C for 10 s, 1 min, 10 min, and 60 min after austenitizing performed at 850 °C for 150 s and the samples were then tempered at 415 °C for 150 s. Effect of these heat treatments on microstructure, hardness and bending properties was then investigated. Results showed that the initial ferrite and pearlite microstructure generally transformed into martensite. Tempered martensitic microstructure was obtained after tempering heat treatment. Hardness of the samples has a decreasing tendency with increasing annealing times at a given annealing temperature. Tempering heat treatment decreases the hardness values obtained after isothermal annealing, as expected. However, hardness values after tempering did not exhibit a significant variation with respect to isothermal annealing time. As compared to original sample, the application of tempering after isothermal annealing increases bending strength, and bending strain also increases getting closer to values exhibited by the original sample.