Ductile iron infinitely chilled Hard cast iron roll grade V (SGV) is suitable for section steel rolling mills and can meet the rolling needs of section steels of different sizes and materials, including angle steel, I-beam, channel steel, etc. SGV rolls can improve the production efficiency of the rolling mill, and reduce downtime during the production process and the frequency of roll replacement, thereby reducing production costs. The rollers are precision machined to ensure that the rolled steel products have high-quality surface finish and dimensional accuracy. Compared with some more expensive roll materials, ductile iron rolls have lower manufacturing costs, but their performance can still meet the requirements of section steel rolling mills and are cost-effective. Ductile iron infinitely chilled cast iron rollers Grade V (SGV) play an important role in profile rolling mills and are widely used in the metal processing industry due to their wear resistance, chilling properties, a wide range of applications, and improved production efficiency.
Hardness HSD: 60-70
Nickel composition %: 1.01-2.0
Suitable for racks: Chinese steel rolling
Usage: Intermediate stands of section mills, bar mills, and wire mills.
| Chemical Composition % | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | C | Si | Mn | P | S | Cr | Ni | Mo | Mg |
| SGⅣ | 2.90-3.60 | 0.80-2.50 | 0.40-1.20 | ≤0.25 | ≤0.03 | 0.20-0.60 | 0.50-1.00 | 0.20-0.80 | ≥0.04 |
| SGⅤ | 2.90-3.60 | 0.80-2.50 | 0.40-1.20 | ≤0.20 | ≤0.03 | 0.30-1.20 | 1.01-2.00 | 0.20-0.80 | ≥0.04 |
| Prosperities & Application | ||||
|---|---|---|---|---|
| Symbol | Hardness | Tensile Strength | Dimension | Application |
| HSD | MPa | MM | ||
| SGⅣ | 55-70 | ≥320 | ￠300-1300 | Intermediate stands of section mills,bar mills and wire mills. |
| SGⅤ | 60-70 | ≥320 | ||
SGV pairs a spheroidal graphite iron body with an infinite chill working layer. This combination is aimed at stands that carry heavy and uneven loads, and it makes the grade a practical, high-performing choice among Section Mill Rolls for intermediate positions.
A hardness of 60-70 HSD gives the pass surface enough resistance to abrasion by hot steel, while leaving the roll machinable for regrooving. Nickel in the 1.01-2.0% range refines the matrix and improves hardenability. This helps hardness decline gradually from the surface toward the core instead of falling away abruptly, which is the essence of an infinite chill profile.
Spheroidal graphite nodules play a separate role. They add core strength and slow crack growth, so the roll can tolerate the bending and torsional stress of large profile passes. In effect, the hard layer handles wear while the ductile body handles load, and neither has to be compromised for the other.
This division of work matters in section rolling. Flanges, webs, and legs are reduced at different rates within the same groove, which creates uneven pressure and localized heat. A roll that is hard only at the surface can chip under these conditions, and a roll that is soft throughout wears out too quickly. The graded structure of SGV is designed to avoid both outcomes.
Because the hardness gradient is gradual, the roll does not lose its protective layer after the first few turn-downs. Grooves can be recut several times and still work in a hard, wear-resistant zone.
Flanged and webbed sections create uneven reductions across the groove. The ductile iron core carries this load without the brittleness found in conventional chilled rolls, reducing the risk of breakage.
Intermediate stands see repeated contact with hot steel followed by water cooling. SGV resists surface roughening and fine thermal cracking, so groove surfaces stay in good condition for longer.
Slow, even wear keeps groove geometry close to its original form. Finished sections therefore hold their dimensions more consistently, and the surface finish stays clean from the start of a campaign to the end.
Longer campaigns mean fewer stand changes, less idle time, and steadier mill rhythm. Production planners gain more predictable schedules and higher effective output.
Ductile iron is less costly to produce than many premium roll grades. For intermediate stands, its performance is more than adequate, so cost per ton rolled remains low and the return on each roll is strong.
By mill type. SGV is developed for section mills and is equally at home in bar mills and wire mills, where intermediate stands face a similar mix of abrasion, thermal cycling, and load variation.
By stand position. The grade is intended mainly for intermediate stands. At this point in the rolling sequence, the stock has already been broken down and the passes begin to define the final shape, so both wear resistance and structural strength are required.
By product shape. Typical products include equal and unequal angles, beams, channels, and other structural profiles, along with a range of bar and wire sizes. Carbon steel and alloy steel grades can both be processed, with roll dimensions and groove layouts adapted to the section being rolled.
By operating pattern. Mills that switch between several sizes benefit most. Since the hard layer extends deep into the barrel, rolls can be reground and reassigned to new groove designs without sacrificing performance.
Nickel strengthens the matrix and improves hardenability, supporting a more uniform hardness distribution below the surface. Keeping it within this range balances working-layer performance with core toughness and manufacturing cost.
Yes. Its intermediate-stand design also suits bar mills and wire mills. The exact grade and groove design should be matched to the product size, rolling speed, and stand conditions of each mill.
It is positioned for intermediate stands. For roughing or finishing positions, the stand load and surface requirements should be reviewed first, so the most suitable roll grade can be recommended for your process.
