4Cr13 is a martensitic stainless mold steel with good corrosion resistance, wear resistance and machinability, which is widely used in plastic molds, small hardware molds and low-load wear-resistant molds. It is a cost-effective stainless mold steel, which is cheaper than S136 and 2083, and can meet the basic corrosion resistance requirements of general plastic processing scenarios. This article will detail the performance characteristics, chemical composition, application scenarios, heat treatment specifications and selection tips of 4Cr13 mold steel, helping you choose the right mold steel for your production needs.

Core Performance Characteristics of 4Cr13 Mold Steel

4Cr13 mold steel has the characteristics of stainless, wear-resistant and easy to process, and its comprehensive performance is suitable for medium and low-end corrosion-resistant mold scenarios:

• Good Corrosion Resistance: 4Cr13 contains about 12-14% chromium, which can form a dense chromium oxide passive film on the surface, effectively resisting the corrosion of weak corrosive plastics (such as ordinary PC, ABS flame-retardant plastics) and mold release agents, avoiding mold rust. It is suitable for general corrosion scenarios, but not for strong corrosive plastics (such as PVC).
• Good Wear Resistance: After heat treatment, 4Cr13 has a hardness of 48-52 HRC, which has good wear resistance and can resist the wear caused by plastic flow during injection molding, ensuring the service life of the mold.
• Excellent Machinability: 4Cr13 has good machinability in the annealed state, which is easy to cut, drill and mill, and can reduce tool wear during processing, improving processing efficiency and reducing processing costs.
• Cost-Effective: The price of 4Cr13 is lower than that of S136, 2083 and other stainless mold steels, which is a cost-effective choice for manufacturers with limited budget and general corrosion resistance requirements.
• Moderate Toughness: 4Cr13 has moderate toughness, which is not easy to crack during processing and use, suitable for simple and medium-complex structure molds.

Chemical Composition of 4Cr13 Mold Steel

The chemical composition of 4Cr13 determines its basic performance, and its detailed composition (mass fraction) is as follows, which is different from S136 and 2083 in carbon and alloy element content:

Applications of 4Cr13 Mold Steel

Due to its cost-effectiveness and good comprehensive performance, 4Cr13 is mainly used in medium and low-end plastic molds and low-load wear-resistant molds, and its application scenarios are concentrated in the following fields:

1. Ordinary Corrosive Plastic Injection Molds

4Cr13 is suitable for processing weak corrosive plastics, which can avoid mold rust and meet the basic production requirements:

• Ordinary PC plastic molds: PC shells, PC accessories, PC daily necessities injection molds (not high-gloss and strong corrosion requirements).
• Flame-retardant ABS plastic molds: Flame-retardant electronic accessories, flame-retardant plastic shells injection molds.
• Food-grade plastic molds: Ordinary food plastic packaging, plastic tableware injection molds (require corrosion resistance and cleanliness).

2. Low-Load Wear-Resistant Molds

With good wear resistance, 4Cr13 is suitable for low-load wear-resistant molds, such as:

• Small hardware molds: Small hardware stamping molds, small hardware forming molds (low load, small size).
• Plastic trimming molds: Trimming molds for plastic products, which need certain wear resistance to withstand repeated trimming operations.

3. Simple Structure Molds

4Cr13 has good machinability and moderate toughness, suitable for simple and medium-complex structure molds:

• Single-cavity plastic molds: Single-cavity injection molds for ordinary plastic parts, easy to process and low cost.
• Small-size molds: Small-size plastic molds, hardware molds, which do not require high precision and performance.

Heat Treatment Guide for 4Cr13 Mold Steel

The heat treatment of 4Cr13 is relatively simple, and the key is to control the quenching and tempering temperature to ensure the balance of hardness and toughness. The recommended heat treatment process is as follows:

1. Annealing (Before Processing)

Purpose: Reduce hardness, eliminate internal stress, improve machinability, and lay the foundation for subsequent processing and heat treatment.

• Annealing Temperature: 800-850℃
• Holding Time: 2-3 hours (depending on the size of the mold blank, ensure uniform heating)
• Cooling Method: Slow cooling (furnace cooling) to 500℃, then air cooling to room temperature
• Annealed Hardness: ≤ 241 HB

2. Preheating (Before Quenching)

Purpose: Avoid uneven heating of the mold during quenching, reduce internal stress, and prevent mold cracking.

• Preheating Temperature: 600-700℃
• Holding Time: 1-1.5 hours

3. Quenching (Core Heat Treatment Step)

Purpose: Form a martensitic structure, improve the hardness and wear resistance of 4Cr13, and enhance corrosion resistance.

• Quenching Temperature: 1050-1100℃
• Holding Time: 1-1.5 hours (ensure the mold is fully austenitized)
• Cooling Method: Oil cooling (cool to 150-200℃, then air cooling to room temperature); avoid water cooling to prevent mold cracking due to excessive internal stress.
• Quenched Hardness: 56-60 HRC

4. Tempering (Improve Toughness and Stabilize Structure)

Purpose: Eliminate the brittleness caused by quenching, improve the toughness of 4Cr13, stabilize the mold structure and size, and adjust the hardness to meet the working requirements.

• Tempering Temperature: 200-250℃ (for high wear resistance); 450-500℃ (for better corrosion resistance and toughness)
• Holding Time: 2-3 hours per time, twice tempering is recommended (the first tempering eliminates internal stress, the second tempering stabilizes the structure)
• Cooling Method: Air cooling to room temperature
• Tempered Hardness: 48-52 HRC (common for plastic molds and low-load wear-resistant molds)

Selection Tips & Common Mistakes for 4Cr13 Mold Steel

Selection Tips

• If you process weak corrosive plastics (ordinary PC, flame-retardant ABS) and have limited budget → Choose 4Cr13 (cost-effective, meets basic corrosion resistance requirements).
• If you need low-load wear-resistant molds (small hardware, plastic trimming) → Choose 4Cr13 (good wear resistance, low cost).
• If you process strong corrosive plastics (PVC) or need high-gloss products → Do not choose 4Cr13; choose S136 or 2083 instead.
• If you need complex structure molds or high-precision molds → Choose 2083 or S136 (better toughness and dimensional stability than 4Cr13).

Common Mistakes

1. Using 4Cr13 for PVC plastic molds → 4Cr13 cannot resist the strong corrosion of PVC, which will lead to mold rust and shorten service life.
2. Neglecting tempering after quenching → 4Cr13 has high brittleness after quenching; insufficient tempering will lead to mold cracking during use.
3. Pursuing high hardness and using excessive quenching temperature → Too high quenching temperature will lead to mold deformation and cracking, affecting mold precision.
4. Confusing 4Cr13 with 2083/S136 → 4Cr13 is a low-end cost-effective product, and its corrosion resistance and polishability are worse than 2083 and S136, which cannot be substituted.

We provide high-quality 4Cr13 mold steel, with complete chemical composition detection reports and heat treatment guidelines, and free custom cutting, forging and heat treatment services. Our professional team can provide you with personalized selection advice according to your plastic material, product requirements and budget. Contact us now to get a free quote and detailed material data sheet!

If you are looking for premium grade 4Cr13 material with optical-grade mirror polishing performance, check out our FT64 High-Precision Plastic Mold Steel Plate, which delivers exceptional corrosion resistance for electronic and optical molds.