Development of High-Cr Roll for Hot Strip Mill with Superior Resistance to Surface Deterioration and to Spalling of Outer Shell

Abstract

In recent years, High-Cr cast iron work rolls have been used at front finishing stands in many hot strip mills instead of Adamite rolls.
We researched and investigated heat treatment to improve the resistance to surface deterioration and centrifugal casting to improve the resistance to spalling of outer shell.
According to the above, our findings are as follows:
In case of 2.8%C-18%Cr roll,
(1) Precipitation of secondary carbide with high wear resistance and martensitization of matrix with high hardness are obtained by destabilizing heat treatment at more than 1000°C.
(2) Regarding to melting bond structure of roll with High-Cr outer shell and spheroidal graphite cast iron core, the roll cast with intermediate layer between outer shell and inner core is sounder than the conventional roll.
This intermediate layer improve the mechanical property and minimize the residual stress.
(3) This type of High-Cr rolls have been used in the actual rolling and we found the clear effects of improved resistance to surface deterioration and to spalling of outer shell.