Metallurgical Grade CaSi

 

Metallurgical Grade Calcium Silicon (CaSi) is a high-performance ferroalloy specifically designed for steel refinement and cast iron modification. Composed of 28-35% calcium (Ca) and 55-65% silicon (Si), it serves as a powerful deoxidizer, desulfurizer, and inclusion modifier in modern metallurgy.

 

Produced in electric arc furnaces through carbothermic reduction, our CaSi ensures consistent quality, high reactivity, and superior performance in demanding industrial applications.

 

 

 

Chemical Composition

 

Element	Content (%)	Function
Calcium (Ca)	28-35%	Enhances deoxidation & controls inclusions
Silicon (Si)	55-65%	Improves fluidity & reduces oxidation
Aluminum (Al)	≤1.5%	Minimizes unwanted impurities
Carbon (C)	≤0.5%	Reduces contamination in high-grade steel
Iron (Fe)	Balance	Provides structural stability

 

Physical Properties

Form: Lumps (10-50mm), Powder (0-5mm), Granules (5-10mm)

Melting Point: ~1200°C

Density: 2.5-2.8 g/cm³

 

Compliance Standards

✔ ISO 5445 | ✔ ASTM A495 | ✔ GB/T 3419

 

 

 

✔ Superior Steel Refinement

• Deep Deoxidation – Removes dissolved oxygen, preventing porosity & defects.
• Effective Desulfurization – Lowers sulfur to <0.005%, enhancing steel toughness.
• Inclusion Shape Control – Converts harmful oxides into harmless globular inclusions.

 

✔ Foundry & Cast Iron Advantages

• Excellent Inoculant – Promotes uniform graphite formation in ductile iron.
• Nodularization Agent – Essential for automotive & pipe-grade castings.

 

✔ Operational Efficiency

• Reduces Slag Volume – Improves metal yield & lowers waste.
• Fast Melting – Saves energy & shortens furnace processing time.

 

 

 

 

 Steel Industry (Primary Use)

• Ladle Furnace Treatment – Secondary metallurgy refinement.
• Continuous Casting – Cleaner steel for high-end applications.

 

 Foundry & Cast Iron Production

• Ductile Iron Manufacturing – Engine blocks, pipes, gears.
• Gray Iron Modification – Improves machinability.

 

 Non-Ferrous Metallurgy

• Aluminum Refining – Removes hydrogen & inclusions.
• Magnesium Production – Used as reduction agent.

 

Cored Wire Injection

• Precision Alloy Addition – Ensures controlled treatment.

 

 

 

 Premium Quality Guaranteed

• Strict Composition Control – Low Al & C for critical applications.
• Multiple Size Options – Lumps, powder & granules for all needs.

 

Reliable Global Supply

• Large Production Capacity – Stable supply for steel mills worldwide.
• Flexible Packaging – Moisture-proof bags, ton bags or bulk containers.

 

Technical Expertise

• 30+ Years Experience – Trusted by leading steelmakers.
• Custom Solutions – Tailored CaSi blends for special requirements.

 

 

 

With increasing demand for:

 

• Ultra-Low Carbon Steel – Green steel initiatives
• High-Performance Castings – Electric vehicle components
• Infrastructure Materials – Corrosion-resistant rebars

 

Metallurgical grade CaSi remains indispensable for advanced metal production.

 

 

 

Contact us today for:

 

Technical Specifications

Competitive Pricing

Customized Solutions

 

 

Metallurgical Grade CaSi – Enhancing Cleanliness in Bearing Steel (GCr15)

 

1. Background

 

A specialty steel mill in Eastern Europe producing GCr15 bearing steel (equivalent to AISI 52100) faced persistent quality rejections from bearing manufacturers. The primary defect was macro-inclusions (>15 µm) containing alumina (Al₂O₃) and spinel (MgO·Al₂O₃). These hard, non-deformable inclusions caused premature fatigue failure during bearing life testing.

The mill's existing secondary metallurgy practice used calcium wire feeding (CaSi cored wire) but with inconsistent results. Rejection rates for "high-cleanliness" bearing steel orders averaged 9–14%, costing over €2 million annually in downgraded material and reprocessing.

 

2. Challenge

 

The specific metallurgical challenges were:

Alumina clogging: Submerged entry nozzles (SEN) in continuous casting showed clogging after just 2–3 heats, requiring frequent changes.

Inclusion morphology: Al₂O₃ inclusions remained angular and clustered instead of being modified to low-melting-point calcium aluminates (e.g., 12CaO·7Al₂O₃).

Calcium recovery instability: Recovery of calcium from standard CaSi wire varied between 8% and 22%, making inclusion engineering unpredictable.

Hydrogen pickup: Some CaSi grades introduced hydrogen, leading to flake formation in large-diameter bars.

The mill required a Metallurgical Grade CaSi product with:

Consistent calcium content (30–33% min)

Controlled aluminum and magnesium trace elements

Low hydrogen potential

Predictable dissolution behavior in liquid steel

 

3. Solution Adopted: Metallurgical Grade CaSi (30% Ca, Low-Al Grade)

 

After benchmarking three suppliers, the mill selected a Metallurgical Grade Calcium Silicon manufactured via aluminothermic reduction with post-treatment to remove residual aluminum. Key specifications:

Parameter	Standard CaSi (previous)	Metallurgical Grade CaSi	Improvement
Calcium (Ca %)	28–31	31–33	Higher & stable
Silicon (Si %)	55–62	55–60	Controlled
Aluminum (Al %)	≤1.5	≤0.4	-73%
Magnesium (Mg %)	≤0.3	≤0.08	-73%
Carbon (C %)	≤0.2	≤0.05	-75%
Phosphorus (P %)	≤0.04	≤0.02	-50%
Sulfur (S %)	≤0.05	≤0.01	-80%
Hydrogen (ppm)	Not spec'd	≤2 ppm	Critical control
Particle size	0.5–2.5 mm	0.2–1.5 mm (cored wire)	Faster dissolution

Additional features:

Low magnesium to prevent spinel (MgO·Al₂O₃) formation

Tight calcium range for precise stoichiometric control of inclusion modification

Vacuum-degassed during production to ensure H₂ ≤ 2 ppm

 

4. Implementation Process

 

Phase 1 – Laboratory evaluation (2 weeks):
Differential thermal analysis confirmed the Metallurgical Grade CaSi melted at 1020°C (vs. 1150°C for standard grade), ensuring faster reaction in the ladle.

Phase 2 – Plant trial on 150-ton ladle furnace (4 weeks):

Steel grade: GCr15 (bearing steel)

Process route: EAF → LF → VD → Continuous casting (billet caster)

CaSi addition: Cored wire feeding at 2.5 m/ton (vs. 3.2 m/ton previously)

Target total oxygen (T.O.) before calcium treatment: ≤12 ppm

Phase 3 – Inclusion characterization (6 weeks):
Samples taken before and after calcium treatment. Automated SEM-EDS analysis of 1000+ inclusions per sample.

 

5. Results (After 6 Months of Production)

 

Inclusion Modification Results

Parameter	Before (Standard CaSi)	After (Metallurgical Grade)	Improvement
Calcium recovery (%)	8–22 (avg 14%)	16–24 (avg 20%)	+43% stability
Alumina (Al₂O₃) present	47% of inclusions	8% of inclusions	-83%
Liquid calcium aluminate (12CaO·7Al₂O₃)	12%	68%	+467%
Spinel (MgO·Al₂O₃)	18%	3%	-83%
Max inclusion size (µm)	35	12	-66%
Inclusions >15 µm (count/cm²)	4.2	0.6	-86%

Casting Performance

Parameter	Standard CaSi	Metallurgical Grade CaSi
Submerged entry nozzle clogging	After 2–3 heats	After 8–10 heats
Casting interruptions per month	11	2
Steel reoxidation incidents	Frequent	Rare

Mechanical & Fatigue Performance

Parameter	Before	After
Bearing fatigue life (L10, hours)	280	510
Cleanliness (ASTM E45 Plate A – B thin)	1.5	0.5
Hydrogen flakes in bars (100t production)	2 incidents	0 incidents

 

6. Metallurgical Analysis

 

The improvement was attributed to:

Controlled aluminum (<0.4%): Residual Al in CaSi does not contribute additional Al₂O₃ inclusions.

Low magnesium (<0.08%): Eliminated spinel formation, which is not modified by calcium treatment.

Higher calcium (31–33%): Achieved the stoichiometric target of dissolved Ca (approx. 15–20 ppm residual Ca in steel) required to transform solid Al₂O₃ into liquid calcium aluminate.

Low hydrogen (<2 ppm): Prevented flake formation in large-section bearing bars.

 

7. Process Optimization

 

With stable calcium recovery, the mill optimized the treatment protocol:

Before: 3.2 m/ton CaSi wire at 2.5 m/s

After: 2.0 m/ton CaSi wire at 3.5 m/s (faster feeding to reach deeper in ladle)

Result: Additional 15% reduction in CaSi consumption while maintaining inclusion control.

 

8. Financial Impact

 

Cost/Revenue Item	Annual Amount (€)
Bearing steel rejection reduction (9% → 2%)	+€1,820,000
Reduced CaSi wire consumption (€45/ton steel saved)	+€380,000
Reduced nozzle changes (€1200 per change × 108 fewer changes)	+€130,000
Premium achieved for "high-cleanliness" certified grade (€25/ton)	+€750,000
Total annual benefit	€3,080,000
Higher cost of Metallurgical Grade CaSi (€190/ton vs standard)	–€92,000
Net annual savings	€2,988,000

 

9. Additional Benefits

 

Faster ladle turnaround (12 minutes saved per heat due to reliable calcium treatment)

Reduced re-sulfuring (less sulfur pickup from CaSi → saving on sulfur wire)

Customer qualification: Two major bearing manufacturers approved the mill as a "preferred supplier" after six months of consistent quality

 

10. Conclusion

 

The switch to Metallurgical Grade CaSi (31–33% Ca, low Al, low Mg, low H₂) enabled a bearing steel producer to reduce large inclusions by 86%, eliminate nozzle clogging for extended campaigns, and achieve a 78% reduction in rejection rates. The higher unit cost of premium CaSi was quickly offset by savings in wire consumption, casting disruptions, and quality claims. For any steelmaker producing aluminum-killed grades requiring high fatigue life (bearing steels, spring steels, gear steels), specification-controlled Metallurgical Grade CaSi is a proven enabler of superior inclusion engineering.

 

11. Recommendation

 

Steel producers should consider upgrading to Metallurgical Grade CaSi when:

Total oxygen before calcium treatment is consistently below 15 ppm

Bearing or spring steel rejections exceed 5% due to oxide inclusions

Submerged entry nozzle clogging occurs within 5 heats

Spinel inclusions (>5%) are detected in final product

Critical success factors: proper argon stirring during CaSi addition, residual calcium target of 10–30 ppm, and regular inclusion rating using automated SEM-EDS.

 

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