1.2312 Anti-corrosion treatment of mold steel

1.2312 mold steel (also known as P20+S, a modified version of P20 with added sulfur for improved machinability) is a pre-hardened tool steel commonly used in plastic injection molds, die-casting dies, and mold bases.

However, 1.2312 is not inherently corrosion-resistant, so anti-corrosion treatment is crucial, especially for molds exposed to moisture, corrosive plastics, or humid environments.

🛡️ Anti-Corrosion Treatment Options for 1.2312 Mold Steel

✅ 1. Nitriding (Gas or Plasma)

• Adds a hard, wear- and corrosion-resistant surface layer (Fe-N compound).

• Operating temperature: ~500–550°C.

• Does not affect core hardness, which is great for pre-hardened steels like 1.2312.

• Depth: ~0.1–0.6 mm (depending on time).

🔸 Pros:

• Improves corrosion resistance and wear resistance.

• No distortion — perfect for finished molds.

🔸 Cons:

• Surface must be cleaned and polished beforehand.

• Can crack under high mechanical loads if too brittle.

✅ 2. Nickel Plating (Chemical or Electrolytic)

• Electroless nickel plating (ENP) is widely used for corrosion protection.

• Adds a uniform, thin (~5–25 µm) coating of nickel-phosphorus alloy.

🔸 Pros:

• Excellent corrosion resistance.

• Conformal coating – even on complex geometries.

• Adds some wear resistance and release properties (great for sticky plastics).

🔸 Cons:

• Surface must be clean and well-prepared.

• Slight dimensional changes (plan accordingly).

✅ 3. PVD Coating (TiN, CrN, DLC)

• Physical Vapor Deposition adds ultra-thin ceramic coatings:

  • TiN (Titanium Nitride) – golden color, wear and corrosion resistant.

  • CrN (Chromium Nitride) – higher corrosion resistance than TiN.

  • DLC (Diamond-Like Carbon) – excellent mold release and corrosion protection.

🔸 Pros:

• Excellent wear + corrosion protection.

• Low friction and anti-sticking properties for mold cavities.

• Minimal dimensional change.

🔸 Cons:

• Requires high-vacuum PVD equipment.

• Cost is higher compared to nitriding or plating.

✅ 4. Passivation (for Short-Term Storage Protection)

• Mild chemical treatment (often nitric or citric acid based) that removes free iron from the surface.

• Creates a thin passive oxide layer to reduce corrosion.

🔸 Pros:

• Quick and easy.

• Good for short-term protection and maintenance.

🔸 Cons:

• Not a long-term or high-stress corrosion solution.

🔩 Summary Table: 1.2312 Anti-Corrosion Options

✅ Best Practice

For long-term performance, a combination of:

• Nitriding for wear + moderate corrosion, or

• Electroless Nickel Plating for strong corrosion resistance, is ideal.

Add regular mold maintenance, protective storage coatings (rust inhibitors), and climate-controlled environments for maximum life.