4Cr17Mo Tool Steel for Molds and Dies

Aobo Steel offers 4Cr17Mo Tool Steel, a specialized martensitic stainless steel engineered for demanding applications, particularly in plastic mold making. This grade offers enhanced mechanical strength and superior corrosion resistance compared to standard Cr13-type steels.

4Cr17Mo is classified as a corrosion-resistant plastic mold steel. Its specific properties make it a reliable choice for tools operating under challenging conditions.

1.  4Cr17Mo Tool Steel Chemical Composition (Typical % Mass Fraction)

The performance of 4Cr17Mo stems directly from its carefully balanced alloy composition:

• Carbon (C):36 – 0.42% (Provides hardness and strength after heat treatment)
• Chromium (Cr):00 – 18.00% (Ensures excellent corrosion resistance)
• Molybdenum (Mo):40 – 0.60% (Increases resistance to pitting and stress corrosion)
• Silicon (Si):≤0.60%
• Manganese (Mn):≤0.80%
• Phosphorus (P):≤0.030%
• Sulfur (S):≤0.030%

This composition delivers a steel that resists corrosive media while maintaining good mechanical properties.

2.  4Cr17Mo Tool Steel Manufacturing and Supply Conditions

At Aobo Steel, we understand the importance of material quality. 4Cr17Mo is typically produced via electric furnace melting, often combined with ladle refining or electroslag remelting (ESR) to ensure high purity and structural homogeneity. This guarantees consistent performance.

We supply 4Cr17Mo in a softened annealed condition, typically with a hardness of ≤230 HBW. This state offers good machinability, simplifying the process of manufacturing complex mold or die geometries.

3.  4Cr17Mo Tool Steel Heat Treatment

The final properties of 4Cr17Mo are determined by heat treatment. A correct process unlocks its full potential.

3.1 Quenching

• Heat to 1020-1050°C.
• Rapid cool (oil quench or salt bath at 500-550°C).
• Result: Achieves a hard martensitic structure, typically with a hardness of 48-51 HRC.

3.2 Tempering

• Reheat the quenched steel to a specific temperature.
• Hold, then air cool.
• Result: Adjusts hardness and toughness. Higher tempering temperatures generally decrease hardness but increase toughness, allowing you to tailor the steel to specific application requirements.

Properly heat-treated 4Cr17Mo delivers high hardness, excellent wear resistance, and strong resistance to stress corrosion.

4. Applications for 4Cr17Mo Tool Steel

Thanks to its combination of machinability, hardness, wear resistance, and corrosion resistance, 4Cr17Mo is an excellent choice for:

4.1 Plastic Molds:

• Molds require high wear resistance and operate under significant loads.
• Molds used in corrosive environments or with corrosive plastics.
• Molds for transparent plastic parts needing a high surface finish.
• Molds for high-precision components.

Cold Work Dies: Dies that demand good corrosion resistance alongside high wear resistance.

5. Surface Enhancement

For even greater surface hardness and wear resistance, 4Cr17Mo can undergo nitriding treatment after the primary heat treatment.