How to Choose the Particle Size of Recarburizer & Key Application Tips

I. Particle Size Selection

1. By furnace type

   • Medium frequency induction furnace: 0.5–5 mm (smaller furnace → finer size).

   • Cupola / Electric arc furnace: 5–15 mm.

2. By casting size

   • Large castings: 3–8 mm for sustained carburizing.

   • Small castings: 0.5–3 mm for rapid dissolution.

3. Uniformity
   Avoid too fine (<0.5 mm, easy burn-off) or too coarse (slow dissolution). Fines (<1 mm) should be <3%.

II. Factors Affecting Absorption Rate

• Too fine → high oxidation loss → low absorption.

• Too coarse → slow dissolution → low absorption.

• Optimal melt temperature: 1460–1550°C. Proper stirring, adding Mn before Si improves absorption.

III. Correct Application

• Addition method: Charge with scrap metal in the middle of furnace (absorption 90–95%) or add into molten steel stream during tapping.

• Moisture protection: Store in dry, ventilated area (5–35°C, RH <80%). Wet recarburizer causes casting blowholes.

• No slag skimming during melting.

• Add in batches to avoid over-oxidation.

• Regular inspection: Check particle size distribution per batch; send to third-party lab (e.g., SGS) for composition verification.

Proper particle size and correct operation significantly increase absorption, reduce costs, and ensure casting quality.