Graphite Steel Rolls for Section and Bar Mills
LONSUN supplies graphite steel rolls for grooved and thermally loaded rolling positions. Selection is based on mill type, stand position, pass geometry, required toughness, hardness, resistance to fire cracking and the performance of the current roll.
Discuss Your Graphite Steel Roll RequirementGraphite steel rolls have a pearlitic matrix containing spherical graphite and carbides. This material direction combines steel-grade strength with practical hardness, while the graphite helps resist fire cracking and scale adhesion. Grade and hardness must still be matched to the actual stand and pass.
Graphite Steel Grades and Stand Applications
Graphite steel is normally considered for long-product duties that need a balance of toughness, thermal stability and groove wear performance.
| APPLICATION AREA | TYPICAL POSITION | COMMON REQUIREMENT | DATA TO REVIEW |
|---|---|---|---|
| Section and bar mills | Intermediate stands | Maintain pass geometry with practical toughness and wear life | Pass drawing, groove depth, load, torque, stock temperature and current wear |
| Long-product mills | Grooved roll positions | Control scale adhesion and thermal cracking around the groove | Product grade, scale, pass profile, cooling, guides and redressing |
| Thermally loaded stands | Positions exposed to repeated heating and cooling | Balance fire-crack resistance with required barrel hardness | Rolling cycle, stoppages, cooling coverage, campaign and crack history |
The GS140–GS190 range represents published chemistry, hardness and strength directions. Final application remains drawing- and stand-specific.
Material Structure and Technical Reference
Spherical graphite, pearlite and carbides work as one material system. The published composition and property ranges below should be reviewed together rather than using barrel hardness as the only selection criterion.
Chemical Composition and Physical Properties
| Symbol | C | Si | Mn | Cr | Ni | Mo | Barrel Hardness (HS) | Roll Neck Hardness (HS) | Tensile Strength (MPa) |
|---|---|---|---|---|---|---|---|---|---|
| GS140 | 1.30-1.50 | 1.30-1.60 | 0.50-1.00 | 0.40-1.00 | - | 0.20-0.50 | 36-46 | ≤46 | ≥540 |
| GS150 | 1.40-1.60 | 1.00-1.70 | 0.60-1.00 | 0.60-1.00 | 0.20-1.00 | 0.20-0.50 | 40-50 | ≤50 | ≥500 |
| GS160 | 1.50-1.70 | 0.80-1.50 | 0.60-1.00 | 0.50-1.50 | 0.20-1.00 | 0.20-0.80 | 45-55 | ≤50 | ≥500 |
| GS190 | 1.80-2.00 | 0.80-1.50 | 0.60-1.00 | 0.50-2.00 | 0.60-2.20 | 0.20-0.80 | 50-65 | ≤50 | ≥450 |
Confirm grade, casting route, hardness scale and test location, microstructure, NDT, dimensions and acceptance criteria in the order specification.
Material behavior, pass duty, cooling and grinding all affect graphite steel roll performance. Use campaign evidence to separate normal wear from an abnormal event.
| SYMPTOM | POSSIBLE AREAS TO CHECK | INFORMATION NEEDED |
|---|---|---|
| Rapid groove wear | Grade/hardness match, pass load, scale, slip, product mix and grinding basis | Pass, tonnage, wear measurements, current diameter and stock removed |
| Fire cracks | Thermal cycling, cooling coverage, stoppage, cobble and incomplete crack removal | Crack map, cooling/event log, campaign and grind/NDT history |
| Scale pickup or product marks | Roll surface, oxide condition, cooling, roughness, guides and pass cleanliness | Defect pitch, product side, roll photographs, roughness and process trend |
| Peeling or spalling | Crack propagation, indentation, local overload, internal indication and redressing quality | Roll ID, diameter, incident history, spall size/depth and NDT result |
| Uneven pass wear | Guide alignment, pass profile, stock temperature, stand alignment and cooling distribution | Axial wear map, drive/operator-side photographs and setup records |
Safety note: visible spalling, deep or growing cracks, neck distress, abnormal vibration or noise, coolant loss or a major cobble should be handled 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 graphite steel 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 |