Alloy Ductile Cast Iron Roll
The alloy ductile cast iron roll is made of acicular nodular cast iron mixing with nickel, chromium, molybdenum. The finished spheroidal graphite iron roll can also be used in the case of a low load. When the finished roll is subjected to a heavy load, it is preferable to use as a nodular cast iron chill roll with high strength and wear resistance. High resistance to accidental breakage even under high rolling pressure.
The ductile iron roll family covers three matrix types — SGP, bainitic and pearlitic — selected by stand position and wear load.
Introduction
The alloy ductile cast iron roll is made of acicular nodular cast iron mixing with nickel, chromium, molybdenum. It can be used in various blanking rolling mills for section steel, bar, wire rod and narrow strip, roughing mills, work roll for seamless steel tube, intermediate stand and finishing stand for section steel, bar, wire rod and narrow strip and rolling mills before finishing rolling for various sections and plate steels. The finished spheroidal graphite iron roll can also be used in the case of a low load. When the finished roll is subjected to a heavy load, it is preferable to use as a nodular cast iron chill roll with high strength and wear resistance.
Technical Advantages of TINVO Alloy Ductile Iron (SGP) Rolls
TINVO’s Alloy Ductile Iron Rolls (also known as Spheroidal Graphite Iron Rolls) are specifically designed for mill stands where high strength and resistance to thermal cracking are paramount. By adding alloying elements such as Ni, Cr, and Mo into the nodular base, we create a roll that bridges the gap between cast iron and steel.
Exceptional Tensile Strength: The spheroidal (nodular) shape of the graphite minimizes the stress concentration effect, providing much higher tensile strength and heat resistance compared to standard grey iron rolls.
Superior Thermal Fatigue Resistance: Our SGP rolls feature a fine pearlitic or acicular matrix, which effectively arrests the propagation of thermal cracks during high-temperature rolling cycles.
Controlled Hardness Gradient: Through advanced heat treatment and alloy control, we ensure a deep and stable hardness layer, making these rolls ideal for Intermediate and Finishing stands of bar, wire rod, and section mills.
Excellent Bite Performance: The unique surface characteristics of ductile iron provide a consistent “bite,” reducing slippage and ensuring stable rolling even under heavy reduction loads.
Bainitic (Acicular) Nodular Iron Rolls
Bainitic Nodular Cast Iron Rolls, also widely referred to as Acicular Ductile Iron Rolls, represent a higher grade of Spheroidal Graphite (SGP) technology. By incorporating higher levels of alloying elements such as Ni, Mn, Cr, and Mo, and employing specialized heat treatments, we transform the matrix into a tough, wear-resistant bainitic structure.
Exceptional Wear Resistance: The bainitic matrix provides a significantly higher hardness (up to 75-85 HSD) compared to pearlitic grades, extending the roll life in high-tonnage mill campaigns.
High Thermal Shock Resistance: The acicular (needle-like) structure is exceptionally effective at absorbing thermal stresses, which prevents the formation of deep fire-cracks during high-speed rolling.
Superior Tensile Strength: These rolls maintain the inherent toughness of ductile iron while offering steel-like strength, making them highly resistant to accidental breakages even under extreme rolling pressures.
Optimal for Heavy-Duty Stands: Due to their robust mechanical properties, they are the preferred choice for heavy duty application, like the finishing stands of wire rod mills and the pre-finishing stands of bar and section mills.
Pearlitic Nodular Iron Rolls
Pearlitic Nodular Cast Iron Rolls, often categorized under the SGP grade, are characterized by a microstructure consisting of nodular graphite and a fine pearlitic matrix. These rolls are the workhorse for modern mills requiring a balance between wear resistance and mechanical strength.
Uniform Hardness Layer: Our specialized heat treatment ensures a remarkably consistent hardness throughout the working layer. This “uniformity” is critical for maintaining stable section dimensions during long rolling campaigns.
Superior Surface Finish: The fine pearlite structure allows the roll to be machined and ground to a very high precision, ensuring that the finished steel products have a smooth, defect-free surface.
Excellent Heat Crack Resistance: Compared to standard iron rolls, the pearlitic matrix provides better resistance to thermal fatigue, significantly reducing the depth and propagation of fire-cracks in hot rolling conditions.
Optimized Machinability: Despite their high wear resistance, these rolls offer excellent machinability, making it easier for your maintenance team to re-groove and restore the roll profile.
Application
Alloy spheroidal graphite iron roll has a lot of usage following as:
- Blooming roll rack of rolling mills for section steel, bar, wire rod and narrow strip
- Rolling mill work roll for seamless steel tube
- Intermediate and finishing roll rack of rolling mill for section steel, bar, wire rod and narrow strip
The nodular cast iron roll usually is used in large blanking machines, section steel tandem rolling, bar and wire rough rolling, intermediate and finish rolling mill. When the finished roll bears a large load, it is best to use a ductile iron roll with a casting groove, high strength and excellent wear resistance.
- For high-precision finishing stands with extreme performance requirements: we recommend our ICDP Rolls.
- For standard load applications and general rolling conditions: our Pearlitic Nodular Iron Rolls offer the best balance of cost-efficiency and reliable mechanical strength.
- For heavy-duty wear applications in bar, section and rod mills: see our Bainitic (Acicular) Nodular Iron Rolls.
Chemical Composition
| Roll | C | Si | Mn | P | S | Ni | Cr | Mo | Mg |
| Cr-Mo semi chilled nodular cast iron roll | 3.20~3.70 | 1.00~2.50 | 0.50~1.00 | ≤0.20 | ≤0.03 | 0.20~0.60 | 0.20~0.60 | ＞0.04 | |
| Cr-Mo infinite chilled nodular cast iron roll | 3.20~3.70 | 1.00~2.50 | 0.50~1.00 | ≤0.20 | ≤0.03 | 0.20~0.60 | 0.20~0.60 | ＞0.04 | |
| Ni-Cr-Mo infinite chilled nodular cast iron roll(I) | 3.20~3.70 | 1.00~2.50 | 0.50~1.00 | ≤0.20 | ≤0.03 | 0.50~1.00 | 0.20~0.60 | 0.20~0.60 | ＞0.04 |
| Ni-Cr-Mo infinite chilled nodular cast iron roll(II) | 3.20~3.70 | 1.00~2.50 | 0.50~1.00 | ≤0.20 | ≤0.03 | 1.01~3.00 | 0.30~1.20 | 0.20~0.60 | ＞0.04 |
| Ni-Mo nodular cast iron roll(I) | 3.20~3.70 | 1.50~2.40 | 0.40~0.80 | ≤0.20 | ≤0.03 | 1.00~2.50 | 0.10~0.50 | 0.40~0.80 | ＞0.04 |
| Ni-Mo nodular cast iron roll(II) | 3.20~3.70 | 1.20~2.40 | 0.40~0.80 | ≤0.20 | ≤0.03 | 2.51~3.50 | 0.10~0.50 | 0.40~1.00 | ＞0.04 |
Bainitic (Acicular) Nodular Iron Rolls
| Roll | C | Si | Mn | Cr | Ni | Mo | Mg |
| Item 1 | 3.00~3.50 | 1.60~2.40 | 0.40~1.00 | 0.10~0.40 | 1.20~2.00 | 0.20~0.60 | ≥0.04 |
| Item 2 | 3.00~3.50 | 1.40~2.20 | 0.40~1.00 | 0.20~1.00 | 1.50~2.50 | 0.30~0.80 | ≥0.04 |
| Item 3 | 3.00~3.50 | 1.20~2.0 | 0.40~1.00 | 0.20~1.00 | 2.00~3.00 | 0.30~0.80 | ≥0.04 |
Pearlitic Nodular Cast Iron Rolls
| Roll | C | Si | Mn | Cr | Ni | Mo | Mg |
| Item 1 | 3.00~3.50 | 1.60~2.40 | 0.40~1.00 | 0.10~0.40 | 1.20~2.00 | 0.20~0.60 | ≥0.04 |
| Item 2 | 3.00~3.50 | 1.40~2.20 | 0.40~1.00 | 0.20~1.00 | 1.50~2.50 | 0.30~0.80 | ≥0.04 |
| Item 3 | 3.00~3.50 | 1.20~2.0 | 0.40~1.00 | 0.20~1.00 | 2.00~3.00 | 0.30~0.80 | ≥0.04 |
Physical Properties
| Roll | Roll-body hardness HSD | Roll-neck hardness HSD | Tensile strength Mpa |
| Cr-Mo semi chilled nodular cast iron roll | 40~55 | 32~50 | ＞300 |
| Cr-Mo infinite chilled nodular cast iron roll | 55~70 | 35~55 | ＞300 |
| Ni-Cr-Mo infinite chilled nodular cast iron roll(I) | 48~70 | 35~55 | ＞320 |
| Ni-Cr-Mo infinite chilled nodular cast iron roll(II) | 48~70 | 35~55 | ＞320 |
| Ni-Mo nodular cast iron roll(I) | 42~52 | 32~43 | ＞400 |
| Ni-Mo nodular cast iron roll(II) | 55~75 | 35~55 | ＞400 |
Bainitic (Acicular) Nodular Iron Rolls
| Roll | Roll-body hardness HSD | Tensile strength Mpa |
| Item1 | 40~55 | ≥360 |
| Item2 | 50~65 | ≥360 |
| Item3 | 60~72 | ≥360 |
Pearlitic Nodular Cast Iron Rolls
| Roll | Roll-body hardness HSD | Tensile strength Mpa |
| Item1 | 40~55 | ≥360 |
| Item2 | 50~65 | ≥360 |
| Item3 | 60~72 | ≥360 |
Metallographic Structure
| Roll name | Metallurgical structure |
| Cr-Mo semi chilled nodular cast iron roll | Pearlite + cementite + nodular graphite + a little ferrite |
| Cr-Mo infinite chilled nodular cast iron roll | Pearlite + cementite + nodular graphite |
| Ni-Cr-Mo infinite chilled nodular cast iron roll(I) | Pearlite + cementite + nodular graphite |
| Ni-Cr-Mo infinite chilled nodular cast iron roll(II) | Fine pearlite + cementite + nodular graphite |
| Ni-Mo nodular cast iron roll(I) | Sorbite + cementite + nodular graphite |
| Ni-Mo nodular cast iron roll(II) | Bainite+ cementite + nodular graphite |
Customization
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