Effect of ambient temperature on the wear performance of typical gun barrel steels

The wear and wear mechanisms of two typical gun barrel steels at room temperature, 200, 400, and 600℃ were investigated by wear, high-temperature hardness, and other types of tests. It was found that the friction coefficients of the two typical gun barrel steels varied little with temperature owing to the formation of triboxides. The wear rate of 32Cr2MoVA first decreased, then increased, and finally decreased with increasing temperature, whereas the wear rate of 30SiMn2MoVA first decreased and then increased with increasing temperature, reaching its maximum at 600℃. The triboxides on the wear surface depended on the temperature, the hardness of the gun barrel steel, and the difference between disc and pin hardness (H_d-H_p) at high temperatures. The temperaturedependent wear of both gun barrel steels depends on the triboxides up to 200℃. Adhesive wear prevailed with simultaneous abrasive wear at room temperature, whereas mild oxidative wear was dominant at 200℃ in both steels. The wear depends on the hardness of the gun barrel steels and disc at 400℃. Severe oxidative wear was dominant at 400℃ in both steels. At 600℃, thick and compact triboxides formed at the wear surface of 32Cr2MoVA owing to the decreasing H_d-H_p; consequently, mild oxidative wear became the dominant mechanism. For 30SiMn2MoVA, the extrusion of pin material, which is attributed to the abrupt increase in H_d-H_p, suggests that extrusion wear prevailed.