Views:0 Author:Site Editor Publish Time: 2021-07-29 Origin:Site
The chemical composition of the high chromium cast iron roll is: 2.0% ~ 4.0%C, 10% ~ 30%Cr, 0.15% ~ 1.6%nI, 0.3% ~ 2.9%Mo. Its essence is a high-alloy white iron with high wear resistance. The chromium content is generally 10% ~ 15%. Its carbides are mainly M7C3 type, which is different from the continuous M8C type carbide of white cast iron. Good wear resistance and high hardness (HV can reach 1800). The matrix is austenitic paper, so the hardness and toughness are combined well.
The actual rolling production shows that the high chromium cast iron roll has good thermal crack resistance. The reason is that a dense and tough chromium oxide film is formed on the surface of the roll, which can reduce the number and depth of thermal cracks. Therefore, high chromium cast iron rolls were very widely used in finishing rolling front stands in the 1980s.
At present, high-chromium cast iron composite rolls have been widely used in hot-rolled strip (steel) continuous rolling mills, roughing and finishing front work rolls, wide and medium-thick plates; roughing and finishing work rolls, and small section steel and bar mill finishing rolls Wait.
There are two forms of heat treatment for high chromium cast iron rolls, one is the subcritical heat treatment below the critical transition temperature, and the other is the high temperature heat treatment above the critical point A3. The pearlite matrix of the surface material of the high chromium roll is expected to have a very fine sheet spacing, and there are large dispersed secondary carbides on the matrix, and it is required to have the lowest possible residual austenite and residual stress, so the latter type is generally selected. Form of heat treatment, specifically normalizing and tempering.