Determining the Optimum Conditions for Heat Treatment of Cold Rolling Mill Rolls by Studying Their Influence on the Microstructure and Properties of the Billet

Krapivina, Polina A.; Gervasyev, Michael A.

doi:10.17516/1999-494x-0152

Cited by 2 publications

(1 citation statement)

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“…The presence of retained austenite in the hardening process of tool-grade steel often causes the steel to have lower hardness than required and poor dimensional stability [15][16][17][18]. Therefore, controlling heat treatment parameters such as feed rate (i.e., the speed at which the roll moves through the induction coil, which is measured in mm/min) during induction hardening is essential [19][20][21]. One must consider the current frequency and its effect on the penetration depth (i.e., the heating depth) of the rolls, as it is well known that the use of high current frequencies leads to low penetration depths and vice versa.…”

Section: Introductionmentioning

confidence: 99%

Effect of feed rate during induction hardening on the hardening depth, microstructure, and wear properties of tool-grade steel work roll

Sapek,

Kalin,

Donik

et al. 2024

Preprint

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Rolls are the most critical yet vulnerable parts of cold rolling mills. It is crucial for them to withstand long rolling campaigns without losing surface roughness or incurring damage. The newly developed rolls are made from tool-grade steel with high roughness, lower wear, and high damage resistance. One of the most important advantages is the elimination of the need for chrome plating, which is currently widely used on standard steel rolls but is ecologically harmful. We investigated type of steel with 8% Cr for use in cold rolling using LOM, XRD, SEM, electron backscatter diffraction (EBSD), hardness measurements, and tribological tests. In this study, a roll with a diameter of 325 mm was ESR remelted and forged, machined to a diameter of 305 mm, and quenched and tempered to simulate industrial roll production. A forged roll was induction heated and hardened at four different feed rates (i.e., 24 mm/min, 30 mm/min, 36 mm/min, and 42 mm/min), tempered at 515°C for 24 hours and again at 480°C for 24 hours, and dissected for in-depth analysis. We identified a clear relationship between the feed rate of the roll during induction hardening and the depth of hardness, the sizes of carbides, and the wear properties of the roll. By reducing the feed rate of the roll through the inductor, we increased the depth of the hardened layer from 16 mm (at a feed rate of 36 mm/min) to 25 mm (at a feed rate of 24 mm/min), which is a 56.25% increase expected to extend the lifespan of the working roll without having negative effects on the wear resistance and other important parameters. XRD analysis showed that the sample had a 0.4% residual austenite, which means it had a significantly lower risk of roll damage during operation than standard steel grades.

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