The shell material of pearlitic nodular cast iron rolls consists of nodular graphite and carbides in an acicular bainitic matrix. The acicular roll material is more highly alloy than the pearlitic roll material. Acicular nodular iron rolls are more wear resistant than pearlitic nodular iron rolls of the same hardness. But pearlitic nodular Iron rolls have superior resistance to thermal cracking.
It is widely used in the intermediate stands and finishing stands of bar mills and small section mills.
This type of roll is often made by centrifugal cast unless the roll has a very deep groove in the body. Its microstructure consists of bainite & pearlite, spheroidal graphite and primary carbide type M3C up to 40%. Although this roll is hard, with proper heat treatment we can improve its cutting properties and eliminate the hard spots.
When the groove in the roll body is very deep, we recommend using rolls static cast with groove to achieve a low hardness drop between the body surface and bottom of the groove.
Chemical Composition
| Grade | C | Si | Mn | P | S | Cr | Ni | Mo | Mg | |
Ccentrifugal | Static | SGA I | 2.90-3.60 | 1.40-2.20 | 0.40-1.00 | ≤0.15 | ≤0.030 | 0.20-1.00 | 3.01-3.50 | 0.50-1.00 | ≥0.04 |
SGA II | 2.90-3.60 | 1.40-2.20 | 0.40-1.00 | ≤0.15 | ≤0.030 | 0.30-1.50 | 3.50-4.50 | 050-1.00 | ≥0.04 | ||
CORE | 2.90-3.70 | 1.40-2.60 | 0.50-1.00 | ≤0.15 | ≤0.030 | ≤0.08 | ≤0.15 | ≤0.50 | ≥0.04 | ||
Mechanical Properties
Tensile Strength (kg/mm²) | ≥350 |
Bending Strength (kg/mm²) | 970-1380 |
Elongation (%) | 0.2-0.5 |
