Pearlitic ductile iron roll II is a pearlitic ductile iron roll used in the intermediate rolling mill. The SGPII roll has high strength and toughness, can withstand high pressure and impact load, and is not prone to breakage or deformation, ensuring the stability of rolling. It is suitable for intermediate rolling mills and can meet the rolling needs of metal blanks of different sizes and materials. The cold hardness requirements are high. The SGPII roll can maintain good hardness and shape stability at high temperatures to ensure the size of the rolled products. Accuracy. SGPII rollers can improve the production efficiency of the intermediate rolling mill, and reduce downtime during the production process and the frequency of roll replacement, thereby reducing production costs. SGPII rollers are widely used in intermediate rolling mills and play an important role in the metal processing industry due to their advantages such as wear resistance, high strength, good cooling and hardening properties, and cost-effectiveness.
Hardness HSD: 55-65
Nickel composition %: 2.01-2.5
Suitable for racks: Chinese steel rolling
| Chemical Composition% | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | C | Si | Mn | P | S | Cr | Ni | Mo | Mg |
| SGPⅠ | 2.90-3.60 | 1.40-2.20 | 0.40-1.00 | ≤0.15 | ≤0.03 | 0.10-0.60 | 1.50-2.00 | 0.20-0.80 | ≥0.04 |
| SGPⅡ | 2.90-3.60 | 1.20-2.00 | 0.40-1.00 | ≤0.15 | ≤0.03 | 0.20-1.00 | 2.01-2.50 | 0.20-0.80 | ≥0.04 |
| SGPⅢ | 2.90-3.60 | 1.00-2.00 | 0.40-1.00 | ≤0.15 | ≤0.03 | 0.20-1.20 | 2.51-3.00 | 0.20-0.80 | ≥0.04 |
| Prosperities & Application | |||||||
|---|---|---|---|---|---|---|---|
| Symbol | Hardness | Tensile Strength | Dimension | Application | |||
| HSD | MPa | MM | |||||
| SGPⅠ | 45-55 | ≥450 | ￠300-1350 | Roughing and slabbing mills; large, medium section mills, wire mills, and narrow strip mills. | |||
| SGPⅡ | 55-65 | ≥450 | |||||
| SGPⅢ | 62-72 | ≥450 | |||||
SGPII sits one step further along the line than the roughing grades. By the intermediate stands, the heaviest breakdown is finished and the stock starts to take on its real cross-section. The roll now has to be strong enough to take heavy loads and hard enough to hold its pass shape. SGPII is built around that balance, and it is a well-matched choice among Intermediate Mill Rolls for lines that cannot afford drift in dimensions.
The grade is supplied at 55-65 HSD, a clear step up from roughing-duty hardness. Nickel is raised to 2.01-2.5%, which strengthens the pearlitic matrix and helps hardness stay consistent as the working surface is dressed back. A ductile iron core underneath keeps the roll resistant to breakage, so the extra surface hardness does not come at the cost of reliability.
Higher surface hardness slows the rate at which grooves open up. Operators spend less time compensating for wear, and the pass stays closer to its design shape for the whole campaign.
Intermediate stands still see pressure spikes when stock temperature or section thickness varies. The tough core of the roll keeps these events from turning into cracks or permanent deformation.
Contact with hot stock raises roll surface temperature again and again. SGPII retains its hardness and shape through this cycle, so the working surface does not soften or distort as a run progresses.
Because groove geometry changes slowly, each bar, section, or rod leaves the stand closer to its target size. This lowers the amount of out-of-tolerance product and reduces rework.
Fewer stand stoppages and less handling work keep the mill running longer between interruptions. The gain in rolling time shows up directly in output.
Pearlitic ductile iron is economical to produce compared with more expensive alloy rolls. For intermediate duty, it delivers the required performance at a modest price per ton rolled.
Rolls that retain usable hardness after regrinding can be reassigned to new groove designs. This suits producers who switch between several sizes within one rolling schedule.
Where customers inspect finished dimensions closely, a roll that resists wear drift gives the mill a margin of safety. The shape stability of SGPII supports this requirement.
Mills that run around the clock need rolls that last through long campaigns. Strength and wear resistance are both required, and this grade supplies each without extreme cost.
The listed range of use covers roughing and slabbing mills, large and medium section mills, wire mills, and narrow strip mills. Within these settings, SGPII is most often placed in intermediate stands, and it can be chosen as Intermediate Mill Rolls for both steel and other metal billets of varied size. Roll dimensions and groove layouts are adjusted to each mill's practice.
It offers higher surface hardness, at 55-65 HSD, and a higher nickel range of 2.01-2.5%. This makes it better for stands where wear control and dimensional accuracy matter more than raw impact tolerance.
Added nickel supports a stronger, more uniform pearlitic structure and helps the roll hold hardness at depth. That consistency is valuable when grooves are recut several times over the roll's life.
Even and sufficient cooling, accurate roll alignment, and regular groove inspection all play a role. Following sound practice in these areas lets the mechanical and thermal properties of Intermediate Mill Rolls work as designed.
