Mechanical Properties of Quenched and Tempered Low Alloy Steel Grinding Media

The effect of tempering temperature on mechanical properties of the quenched low alloy steel was studied. The as-received low alloy steel samples were heated to 950 °C, held for 30 min, and then oil-quenched. The as-quenched samples were finally tempered in the temperature range of 200–600 °C for 30 min. The chemical composition of as-received alloy steel was determined using spectrometer. The microstructures of the samples were observed using optical microscope. A Rockwell hardness test was done to measure the hardness of the alloy steel samples, and a Charpy impact test were conducted to measure the impact toughness of the samples. The results showed the microstructures of the as-quenched and as-tempered samples consist of martensite with different orientation and small inclusions of irregular shapes. Compared with the as-received low alloy steel, the hardness of the quenched steel increased while the impact energy decreased. In comparison with the quenched samples, increasing tempering temperature in the range of 200–600 °C would improve the impact energy of the tempered steels, and it significantly increased above 400 °C.