Effects of Heat Treatment Parameters on Properties of AISI M2 High-Speed Steel
The AISI M2 high-speed steel is by far one of the most widely used and versatile tool steels. This offers excellent wear resistance, high strength, and good toughness, making it suitable for numerous applications including cold hobbing, milling, and forming. In addition, with its good resistance to thermal fatigue and tempering stability, M2 can easily be heat treated to obtain the desired properties.
Heat treatment is one of the key factors in affecting the properties of AISI M2 steel. Heat treatment parameters such as heating rate, temperature, and cooling rate play an important role on the mechanical and physical properties, such as hardness, strength, and toughness for the M2 steel parts. In this paper, the effects of heat treatment parameters on the mechanical and physical properties of AISI M2 high speed steel is studied.
The AISI M2 high speed steel parts were subjected to various heat treatment processes, including a traditional heating process of 845°C for 40 minutes and an austenization process of 815°C for 1 hour. Following the heating process, the parts were cooled at different rates: air cooling, oil quenching, and air quenching. These processes were repeated three times, with and without tempering treatments. The hardness of the parts were then measured and compared between the different heat treatment processes.
The results of the tests show that the heat treatment parameters such as the heating rate, temperature, cooling rate, and tempering processes have a direct effect on the hardness of the parts. The highest hardness levels were achieved with the fastest heating and cooling rates and with tempering treatments. The hardest parts were achieved with a rapid heating and cooling rate followed by tempering, with temperatures ranging from 845°C to 815°C, and cooling rate ranging from air cooling to oil quenching.
The tests also revealed that a proper balance is needed between the heating and cooling rates. Parts heated too quickly and cooled too slowly will result in an increase in hardness, but the parts will become brittle due to the presence of the retained austenite. On the other hand, parts heated too slowly and cooling too quickly will result in a decrease in hardness, as the formation of martensite can result in a decrease in hardness due to the inability of the austenite to transform.
In addition to the effects of the heating and cooling rates, it is shown that the tempering process has a significant effect on the properties of the AISI M2 high-speed steel parts. In tempering, the hardened parts are heated at lower temperatures in order to achieve the desired level of hardness and toughness. The tempering process helps to promote the development of the wear resistance of the parts and reduces the risk of cracking and brittleness in the part.
From the results of this experiment, it is concluded that heat treatments plays an important role in determining the mechanical and physical properties of the AISI M2 high-speed steel parts. The study demonstrates that an appropriate balance between heating and cooling rates is essential to achieving the desired properties, and that a tempering process is essential to reach optimal levels of hardness and toughness. This shows that through a proper understanding of the heat treatment process, the properties of the steel parts can be significantly improved and optimized.
