Metallographic diagram of W18Cr4V (heated to 1240°C. quenched oil)

The present paper aims to provide an evaluation of the microstructure of W18Cr4V following heat treatment processes. In this paper, a sample of W18Cr4V is heated to 1240 ℃ and quenched in oil to reveal its microstructure.

The W18Cr4V sample stock is first heated to 1240 °C. Then, the sample is quenched in oil to cool it down to room temperature. After the heating and quenching process, metallophobia is performed on the sample to observe the microstructure. From the metallophobia analysis, it is found that the microstructure of the sample consists of pearlite, tempered bainite, and retained austenite.

The pearlite structure, an interleaving of ferrite and cementite layers, is observed in the form of needle-like structures, which is the result of slow cooling from the heat treatment process. The transformation of the austenite to pearlite has occurred, as evidenced by the presence of ferrite and cementite.

The presence of tempered bainite is also identified by the metallography. Bainite, a hardened and tempered crystalline structure, is formed from the transformation from austenite to tempered bainite. This transformation is the result of heating at a moderate temperature and cooling at a rate higher than the pearlite formation rate.

Finally, the retained austenite is observed by metallography. The retained austenite is the uncrystallized austenite that is still present after the heat treatment process. The retained austenite is present in lower percentages compared to the pearlite and the tempered bainite, indicating the transformation of austenite to the two hardened and tempered structures.

It is observed that the microstructure of the W18Cr4V sample after heat treatment consists of pearlite, tempered bainite, and retained austenite. This microstructure is formed through the transformations of the austenite. The pearlite is formed through slow cooling, while the tempered bainite is formed through the heat treatment processes of moderated temperatures and accelerated cooling rates. The presence of retained austenite is also observed, although in lower percentages compared to pearlite and bainite.

W18Cr4V is a high-carbon high-chromium alloy with tungsten, molybdenum and vanadium added. Its main features are high strength, high-temperature strength, wear resistance and corrosion resistance. The alloy is widely applied in the production of corrosion resistant parts, mechanical structures and automotive parts.

In order to obtain the optimal properties of W18Cr4V, heat treatment is necessary. The commonly used heat treatment method is quenching and tempering. First, heat the alloy up to 1240℃, and then put it into the quenching tank quickly, so that the martensite and carbide are precipitated to form a martensite structure, which can improve the wear resistance and hardness of the material. Finally, temper the material slowly to refine the structure, reduce the internal stress, and improve the plasticity and toughness of the material.

Metallographic analysis reveals that after heat treatment, W18Cr4V alloy has a two-phase structure. The matrix is composed of spherical carbide and tough martensite, with a hardness of HRC 45-50. This combination of ductility and wear resistance makes W18Cr4V ideal for manufacturing high-strength components for industries such as aerospace and automotive, and for tooling applications.

By optimizing the composition of W18Cr4V and using high-precision thermal processing techniques, its wear resistance and corrosion resistance can be further improved. The heat-treated high-carbon high-chromium alloy W18Cr4V is widely applied in the manufacture of metallurgical components, machine tools and automotive parts, to ensure their durability and high service life.