AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 Hot Work Tool Steel

Product Overview

AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 falls under the category of hot work tool steel, a class of materials engineered to withstand repeated exposure to high temperatures (often 500–800°C) and mechanical stress. Its cross-standard compatibility is a major advantage: it corresponds to ASTM A681 L6 (U.S.), DIN 17350 55NiCrMoV6 1.2713 (Germany), JIS G4404 SKT4 (Japan), and GB/T 1299 5CrNiMo (China), making it easy to integrate into existing production lines worldwide.

The core appeal of this steel lies in its balanced chemical composition, which includes elements like nickel (Ni), chromium (Cr), and molybdenum (Mo) to boost toughness and wear resistance. For example, Ni content ranges from 1.25–2.00% (AISI L6) to 1.50–1.80% (DIN 1.2713/JIS SKT4), a key factor in resisting impact damage during forging or extrusion. Additionally, the low phosphorus (P ≤ 0.030%) and sulfur (S ≤ 0.030%) content minimizes brittleness, ensuring long service life for tools made from this material.

Hunan Qilu Steel offers flexible supply options for AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4, including hot-rolled bars (Φ10–Φ190mm), hot-forged bars (Φ200–Φ600mm), hot-rolled plates (10–60mm thick), and hot-forged blocks (260–500mm thick). All products come with controlled length (2000–5800mm) and precise surface finishes—from black forged (tolerance +0/+5mm) to grinding (tolerance +0/+0.05mm)—to reduce post-processing time for customers.

Product Features

Optimized Chemical Composition for Enhanced Performance

The chemical makeup of AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 is tailored to meet the demands of hot work applications. Each element plays a critical role in defining the steel’s properties:

Carbon (C): Ranges from 0.50–0.75% (0.50–0.60% for DIN 1.2713/JIS SKT4; 0.65–0.75% for AISI L6). Carbon enhances hardness and wear resistance, while the controlled range prevents excessive brittleness.

Chromium (Cr): 0.6–1.2% (AISI L6) to 0.8–1.2% (JIS SKT4). Cr forms hard carbides, improving resistance to abrasion—essential for tools that shape metal components repeatedly.

Molybdenum (Mo): 0.25–0.55% (0.25–0.35% for DIN 1.2713; 0.35–0.55% for JIS SKT4). Mo boosts thermal stability, allowing the steel to retain hardness even at high temperatures.

Vanadium (V): 0.05–0.15% (DIN 1.2713/JIS SKT4 only). V refines grain structure, enhancing toughness and reducing the risk of cracking under thermal cycling.

This composition ensures the steel outperforms generic tool steels in environments where heat and impact are constant, such as forging shops or die-casting facilities.

Superior Hardness and Hardenability

Hardness and hardenability are critical for tool steel, as they determine how well a tool retains its shape and sharpness. AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 excels in both areas:

Annealed Condition: Maximum hardness of HB 248 (cold-drawn condition: HB 262 max). This soft state makes the steel easy to machine, allowing manufacturers to shape it into complex tool geometries (e.g., forging die cavities) without excessive wear on cutting tools.

Hardened & Tempered Condition: Minimum hardness of HRC 46. After heat treatment (preheat to 649°C, quench at 830–850°C in oil, temper at 490–510°C), the steel develops a uniform, high-strength microstructure that resists deformation under heavy loads.

Its excellent hardenability means even large-section tools (e.g., Φ600mm forged blocks) achieve consistent hardness throughout, avoiding weak spots that lead to premature failure.

Exceptional Thermal Fatigue Resistance

Thermal fatigue—cracking caused by repeated heating and cooling—is a common issue for hot work tools. AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 addresses this with its ability to withstand thermal cycling without degradation.

During forging or die-casting, tools made from this steel are exposed to rapid temperature changes (e.g., from 800°C to room temperature). The steel’s balanced alloy content (especially Cr and Mo) forms a stable oxide layer that reduces heat absorption, while its fine grain structure minimizes internal stress. This translates to a longer tool life: tests show that forging dies made from DIN 55NiCrMoV6 1.2713 last up to 30% longer than those made from standard hot work steels.

Rigorous Quality Inspection

Hunan Qilu Steel prioritizes quality control for AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4, implementing strict testing protocols to ensure every batch meets international standards:

Ultrasonic Testing: Complies with EN10228-3 Class III or SEP 1921-84 D/D, detecting internal defects (e.g., voids, inclusions) that could compromise tool performance.

Chemical Analysis: Each coil or bar undergoes spectral analysis to verify chemical composition, ensuring alignment with ASTM, DIN, or JIS standards.

Hardness Testing: Random samples are tested for hardness at multiple points to confirm consistency across the product.

These measures guarantee that customers receive steel with reliable, predictable properties—critical for high-volume manufacturing.

Applications

Hot Work Dies

The primary application of AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 is hot work dies, where its thermal fatigue resistance and toughness are most valuable:

Forging Dies: Used for heavy-duty forging processes, such as hammer forging and press forging. These dies shape large metal components like gears, crankshafts, and connecting rods—parts that require high precision and strength. The steel’s HRC 46+ hardness resists wear from repeated metal-on-metal contact, while its toughness prevents cracking during high-impact forging.

Extrusion Dies: Ideal for hot extrusion of non-ferrous metals (aluminum, copper) into profiles, pipes, or rods. The steel’s ability to retain hardness at 500–600°C ensures consistent extrusion quality, even for long production runs.

Die-Casting Molds: Suitable for die-casting zinc, aluminum, and magnesium alloys (common in automotive and electronics components). The steel’s resistance to molten metal corrosion and thermal cycling extends mold life, reducing downtime for mold replacement.

Cold Work Tools

While designed for hot work, AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 also performs well in low-temperature applications that require high impact resistance:

Thick Plate Punching Dies: Used to punch holes in thick steel plates (6–20mm thick) for construction or machinery parts. The steel’s toughness absorbs the impact of punching, preventing die chipping.

Heavy-Duty Shear Blades: For cutting large steel billets or thick sheets. The Cr-rich composition enhances wear resistance, ensuring the blades stay sharp for extended periods.

Cold Heading Dies: Shapes bolts, nuts, and other fasteners by compressing metal at room temperature. The steel’s hardness and ductility balance allows it to withstand the high pressure of cold heading without deformation.

Plastic Molds

In plastic manufacturing, AISI L6 / DIN 55NiCrMoV6 1.2713 / JIS SKT4 is used for molds that require durability and polishability:

Engineering Plastic Injection Molds: For molding high-performance plastics (e.g., nylon, polycarbonate) used in automotive or aerospace parts. The steel’s smooth surface finish (achievable via polishing) ensures plastic parts have a flawless appearance, while its wear resistance handles high-volume production.

Blow Molds: Used to make plastic containers (e.g., bottles, jars). The steel’s thermal stability resists heat buildup during blow molding, preventing mold warping and ensuring consistent container dimensions.

FAQ

What are the equivalent grades of DIN 55NiCrMoV6 1.2713?

DIN 55NiCrMoV6 1.2713 has direct equivalents in major international standards to simplify global sourcing:

U.S. Standard (ASTM A681): AISI L6

International Standard (ISO 4957): 55NiCrMoV6

Japanese Standard (JIS G4404): JIS SKT4

Chinese Standard (GB/T 1299): 5CrNiMo

All these grades share similar chemical compositions and performance characteristics, making them interchangeable in most applications.

What heat treatment process is recommended for AISI L6 steel?

For optimal performance, AISI L6 should undergo the following heat treatment:

Annealing: Heat to 780–800°C, then cool slowly in a furnace. This reduces hardness to HB ≤ 248, making the steel easy to machine.

Quenching: Preheat to 649°C, then heat to 830–850°C in a salt bath furnace. Quench in oil to achieve maximum hardness.

Tempering: Heat to 490–510°C in a furnace, then cool in air. This step relieves internal stress and stabilizes the microstructure, resulting in a final hardness of HRC ≥ 46.

Hunan Qilu Steel can also provide pre-heat-treated steel upon request, saving customers processing time.

Can Hunan Qilu Steel provide custom sizes for DIN 55NiCrMoV6 1.2713?

Yes. While standard sizes include hot-rolled bars (Φ10–Φ190mm), hot-forged bars (Φ200–Φ600mm), and plates (10–250mm thick), Hunan Qilu Steel offers custom dimensions to meet specific customer needs. For example:

Custom-forged blocks up to 500mm thick and 1000mm wide.

Cut-to-length bars (shorter or longer than the standard 2000–5800mm).

Special surface finishes (e.g., polished or peeled) with tighter tolerances (+0/+0.1mm for peeled surfaces).

To request a custom size, contact Hunan Qilu Steel via email (enquiry@qilumetal.com) or WhatsApp (+86-15084978853) with your requirements.

What is the maximum sulfur content in JIS SKT4?

JIS SKT4 has a strict sulfur limit to ensure toughness: S ≤ 0.020% (lower than the 0.030% limit for AISI L6 and DIN 1.2713). This low sulfur content reduces the risk of brittle fracture, making JIS SKT4 particularly suitable for applications that require high impact resistance, such as heavy-duty forging dies.

How does AISI L6 compare to other hot work tool steels like AISI H13?

While both are hot work tool steels, AISI L6 and AISI H13 differ in composition and application:

AISI L6: Higher Ni content (1.25–2.00%) for superior toughness, making it ideal for high-impact applications (e.g., hammer forging dies). It has a lower Mo content (0.50% max) than H13.

AISI H13: Higher Cr (5.00–5.50%) and Mo (1.25–1.75%) content for better thermal stability, suited for high-temperature applications (e.g., aluminum die-casting molds).

For applications that prioritize impact resistance over extreme temperature tolerance, AISI L6 is the better choice.

What quality certifications does Hunan Qilu Steel’s 1.2713 steel hold?

Hunan Qilu Steel’s DIN 55NiCrMoV6 1.2713 steel complies with multiple international certifications, including:

DIN 17350 (German standard for tool steels).

ASTM A681 (U.S. standard for hot work tool steels).

ISO 4957 (international standard for tool steels).

EN10228-3 Class III (ultrasonic testing for internal defects).

These certifications ensure the steel meets global quality benchmarks, making it suitable for export to markets in Europe, North America, and Asia.

1: Steel equivalent

2: Chemical composition

3: Surface hardness and hardenability.

4: Supply size & Tolerance & Stock size