SGP Rolls for Roughing and Intermediate Stands
LONSUN supplies nodular pearlitic cast iron rolls, also known as SGP rolls, for section, bar, wire and universal mill duties. Selection is based on stand position, required strength, barrel hardness, graphite and carbide structure, current wear and operating conditions.
Discuss Your SGP Roll RequirementSGP rolls contain nodular graphite and carbides in a pearlitic matrix. Compared with indefinite chilled cast iron, the graphite changes from flake to spheroidal form, supporting higher strength. SGP rolls can be made by static casting or centrifugal double-pour casting according to the roll design and application.
SGP Grades and Stand Applications
The SGP I–III range covers progressively different nickel and hardness directions for long-product and universal-mill applications.
| APPLICATION AREA | TYPICAL POSITION | COMMON REQUIREMENT | DATA TO REVIEW |
|---|---|---|---|
| Medium section, bar and wire mills | Roughing stands | Provide strength and stable wear under heavy long-product passes | Pass, reduction, torque, temperature, cooling and current material |
| Bar mills | Intermediate and finishing stands | Maintain groove geometry and product dimensions through the campaign | Pass profile, speed, product mix, guides, wear map and grinding |
| Universal mills | Roll sleeves | Match sleeve strength, hardness, fit and service position | Sleeve and shaft drawing, interference, mounting method, load and cooling |
Final grade and casting route are confirmed against the roll drawing, stand duty, required hardness and current performance baseline.
Material Structure and Technical Reference
The published SGP chemistry and property ranges describe the available material directions. Carbon, silicon, nickel, molybdenum and magnesium must be considered with graphite morphology, carbide level and heat treatment.
Chemical Composition
| Symbol | C | Si | Mn | Cr | Ni | Mo | Mg |
|---|---|---|---|---|---|---|---|
| SGP I | 2.90-3.60 | 1.40-2.20 | 0.40-1.00 | 0.10-0.60 | 1.50-2.00 | 0.20-0.80 | ≥0.04 |
| SGP II | 2.90-3.60 | 1.20-2.00 | 0.40-1.00 | 0.20-1.00 | 2.01-2.50 | 0.20-0.80 | ≥0.04 |
| SGP III | 2.90-3.60 | 1.00-2.00 | 0.40-1.00 | 0.20-1.20 | 2.51-3.00 | 0.20-0.80 | ≥0.04 |
Physical Properties
| Symbol | Barrel Hardness | Roll Neck Hardness | Tensile Strength (MPa)* |
|---|---|---|---|
| SGP I | 45-55 HS | 35-55 HS | ≥350/450 MPa |
| SGP II | 55-65 HS | 35-55 HS | ≥350/450 MPa |
| SGP III | 62-72 HS | 35-55 HS | ≥350/450 MPa |
* The published tensile-strength cells use paired values (≥350/450 MPa). Confirm which value applies to the selected casting route, together with hardness scale, test location and acceptance method.
A visible symptom should be reviewed against the SGP grade, casting route, pass duty, cooling, mill incidents and grinding history.
| SYMPTOM | POSSIBLE AREAS TO CHECK | INFORMATION NEEDED |
|---|---|---|
| Rapid groove wear | Grade/hardness match, abrasion, scale, slip, pass load and grinding basis | Stand, pass, tonnage, wear map, current diameter and stock removed |
| Fire cracks | Thermal cycling, uneven cooling, stoppage, cobble and incomplete crack removal | Crack map, cooling/event log, campaign and grind/NDT history |
| Peeling or spalling | Surface crack growth, indentation, local overload, casting indication and redressing quality | Roll ID, diameter, incident record, photographs, spall depth and NDT result |
| Uneven pass wear | Guide alignment, pass profile, top/bottom load balance, stock temperature and spray coverage | Axial measurements, setup record, pass drawing and drive/operator-side photographs |
| Neck or sleeve-fit distress | Bearing/chock condition, alignment, fit, fillet geometry, torque and handling | Drawing, damage location, assembly data, load/event history and inspection record |
Safety note: visible spalling, deep or growing cracks, neck or sleeve distress, abnormal vibration/noise, coolant loss or a major cobble requires action under the mill’s own safety procedure.
RFQ and Procurement Checklist
A complete RFQ reduces repeated clarification and prevents the quotation from being based only on size and hardness. The buyer’s data and the supplier’s confirmation should form one technical-commercial baseline.
| RFQ ITEM | BUYER PROVIDES | LONSUN CONFIRMS |
|---|---|---|
| Drawing and dimensions | Drawing revision, barrel and neck dimensions, fillets, grooves or pass details, and mounting features | Manufacturing scope, tolerances, machining, working layer where applicable, and drawing exceptions |
| Mill and application | Mill type, stand, roll function, rolled product, steel grade and pass | Proposed SGP grade, hardness and application basis |
| Operating conditions | Rolling force, torque, reduction, speed, stock temperature, cooling and lubrication where used | Material direction, key operating risks and inspection conditions |
| Current performance | Current roll material, hardness, campaign, wear, grinding and incident history | Comparison basis, evaluation method and technical risks to monitor |
| Quality documents | Required chemistry, hardness, microstructure, NDT, dimensions and third-party inspection | Test method, coverage, acceptance criteria and document list |
| Commercial requirement | Quantity, destination, required delivery date, packaging and Incoterm | Price basis, production scope, delivery basis, packing and quotation validity |