Papers by Keyword: High Speed Steel Roll

Abstract: A study on solidification process of centrifugal cast high-speed steel (HSS) rolls and the crack forming condition is discussed. The result was represented that the crack forming was because of the solidification layer strength of HSS roll was low, and a clearance between the solidification layer and the mould, and the solidification layer of HSS roll could not endure a large centrifugal pressure. In common centrifugal casting, the free solidification constriction of HSS rolls was difficult, which accelerated the crack propagation. The appearance of mesosphere and axial solidification was unfavorable to obtaining the compact roll structures, which accelerated HSS rolls to crack.

Abstract: The effects of roll materials, mould parameter, pouring parameter and cooling parameter on the crack of high speed steel (HSS) roll fabricated by a centrifugal casting have been analyzed. The modification of HSS roll was researched. The structures and properties of HSS roll modified by potassium and rare earth were improved. The hot tearing force of modified HSS roll increased by 32.77% and reached 158N. Modification was able to decrease the line constriction. The adoption of variable speed centrifugal casting technique, variable flux pouring technique and variable speed solidification cooling technique was able to adjust the temperature field and stress field of the roll, which benefited the filling and solidification of molten steel and eliminated the crack of HSS roll.

Abstract: The influence of rare earths(RE) and Mg compound modification on eutectic carbide morphology and matrix of high speed steel(HSS) roll was investigated. The results show that the matrix can be refined by the RE-Mg compound modifier, the eutectic carbides are inclined to turn into small lump, whose distribution is homogeneous. After modification, the heat conductivity coefficient of HSS is increased and heat expansion coefficient is decreased. Moreover, RE-Mg modification is able to increase the cycles of thermal fatigue crack initiation and decrease the propagation rate. After cycling 700 times at the condition of heating at 600oC and cooling in 25oC water, the length of thermal fatigue crack is lessened by 41.12%.