Description

HSS rolls are aka high speed rolls, are becoming more and more popular for bar mills finishing stands or hot strip mills. However there’re different chemical content & working layer depth between these two applications.

Advantages of HSS rolls：

1, For ordinary rolls, its working layer is distributed by M3C or M7C3 eutectic compounds, which has low hardness. On the contrary, high speed steel rolls working layer/shell employ high-carbon, high alloy, in which distributed by MC、M2C and M6C; MC and M2C are the dominant carbides.

2, Due to the chemical addition of Vanadium, chromium, tungsten, molybdenum, niobium and other alloy element for HSS roll outer shell. Thus, it has good thermal stability, high hardness under high-temperature, and excellent wear-resistance as hot work rolls.

3, HSS rolls possess good hardenability; the hardness hardly drops from barrel surface to inner working layer. Therefore, the rolls from outside to inside have similar good wear resistance.

4, Because spin-casting high speed steel outer shell can employ graphite steel or nodular iron as core material. Thus, journal has good strength, and core has little chance for breakage. In that case, improves bending strength of rolls, which is good for rolling strips.

5, While the HSS roll is working, under good cooling conditions, barrel surface can form thin & compact oxidation film. This type of film will not be so easy to fall off, thus improves the waerability of rolls. Compared to other ordinary rolls, HSS rolls wear less in the beginning, which is good for its waerability.

6, The hardness of ordinary rolls drops while temper temperature rises. On the other hands, HSS rolls keep a hardness above 80HS, when the temper temperature is 550℃. Due to this, it has excellent roll-failure resistance.

7, HSS rolls have big swelling factor, good thermal conductivity, even the grooves wears due to rolling process. However, barrel will swell, in return reduce the grooves sizes, thus keeps stable shapes of grooves. Especially, while rolling bar or rebars, it has better control of input material negative allowances.