Evaluation of Mechanical Properties of Medium Carbon Low Alloy Forged Steels Quenched in Water, Oil and Polymer

Samples of medium carbon low alloy forged steels are investigated after heating to a maximum hardening temperature at 8550c in electric furnace and the soaking period of 60 minute. Step tempering is done on the hardened samples and quenched in water, oil and polymer, polyethylene glycol (PEG) H− (O−CH2−CH2)n−OH separately. The evaluation of mechanical properties was investigated using Hounsfield tensometer for tensile test, Brinell hardness tester for hardness test, Charpy test to determine the amount of energy absorbed by a material during fracture and finally the microstructure of the all quenched samples were studied using Scanning Electron Microscope. The tensile strength, hardness and impact energy values of the quenched samples were relatively higher than those as-received samples, suggesting improved mechanical properties. However, samples quenched in PEG displayed better properties compared with that of water, oil quenched and as- received samples. The microstructure consists of fine tempered martensite are in hardened and tempered condition. Heat treated specimens have fine tempered martensite structure with small amount of bainite. The formation of martensite structures gives the samples higher hardness