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D2 1.2379 SKD11 Cold Work Tool Steel

D2 Cold Work Tool Steel offers excellent wear resistance, high hardness, and compressive strength. With good hardenability and dimensional stability, it is ideal for blanking dies, punches, and forming tools.

Standard: AISI D2, DIN 1.2379, JIS SKD11, GB Cr12Mo1V1
Technique: EAF + LF + VD or ESR, forged, multi-directional forging ratio ≥4, spheroidized annealed
Shape: Round, Flat, Plates, Blocks
Heat treatment: Supplied in annealed condition, hardness ≤255 HBW; pre-hardened to 58–62 HRC (quenched and tempered) available on request
Surface Treatment: Black (hot-rolled / forged surface), turned, milled / ground, sawn ends.
Tolerance: flat bars & plates thickness: +0.5/-0.0 mm (turned); forged blocks: ±0.2 mm
MOQ: 1 Ton

We supply AISI D2 in various custom sizes

Chemical Composition (%)

Grade	C	Si	Mn	P (≤)	S (≤)	Cr	Mo	V
1.2379	1.45–1.60	0.10–0.60	0.20–0.60	0.030	0.030	11.00–13.00	0.70–1.00	0.70–1.00
D2	1.40–1.60	0.10–0.60	0.20–0.60	0.030	0.030	11.00–13.00	0.70–1.20	0.50–1.10
SKD11	1.40–1.60	≤0.40	≤0.60	0.030	0.030	11.00–13.00	0.80–1.20	0.20–0.50
Cr12Mo1V1	1.40–1.60	≤0.60	≤0.60	0.030	0.030	11.00–13.00	0.70–1.20	0.50–1.10

Main characteristics of D2 tool steel

D2 | 1.2379 | SKD11 tool steel applications

D2 steel for Precision Stamping Die

Exceptional wear resistance and high compressive strength enable 1.2379 to maintain tight tolerances and sharp cutting edges in high-volume precision stamping.

D2 steel for Cold Extrusion & Deep Drawing Die

Superior anti-galling properties and dimensional stability minimize pick-up and ensure excellent surface finish under extreme cold forming pressures.

D2 steel for Thread Rolling Die

High attainable hardness and excellent fatigue resistance allow 1.2379 thread rolling dies to produce accurate threads consistently over extended production runs.

Our Production Technology For 1.2379 (D2 / SKD11 / Cr12Mo1V1) Cold Work Tool Steel

Ultrasonic testing (UT) 100% as per SEP 1921, ASTM A388, or EN 10228-3 (upon request)
Micro Cleanliness as per ASTM E45 or DIN 50602
Spheroidized microstructure as per relevant tool steel standards
Macrostructure, microstructure, grain size, and mechanical properties shall meet the standards specified in GB/T 1299-2025 for Tool and Die Steels
Delivery condition: Soft annealed, hardness max. 250-255 HB (≈ 22-26 HRC)

mechanical properties & heat treatment of D2 steel

Heat temperature	Start forging temperature	Finish forging temperature	Cooling method
1100 – 1150 °C	1050 – 1100 °C	≥ 850 °C	Pit, sand, or furnace cooling

Annealing

Heat slowly to 800 – 850°C (1472 – 1562°F) and hold for 2 – 5 hours (or 4–6 hours for larger sections)
Cool slowly in the furnace at a controlled rate of 10 – 20°C/h down to approximately 600°C
Then air cool to room temperature
Hardness after annealing: max. 250 HB

Hardening

Preheating (two-stage, required):
First stage: 550 – 600°C — hold for 30 minutes per 25mm of section thickness.
Second stage: 800 – 850°C — hold for 30 minutes per 25mm of section thickness
Austenitizing temperature (selection based on application):
980 – 1000°C — lower temperature range, minimal deformation, suitable for high dimensional stability requirements.
1020 – 1040°C — optimal range for secondary hardening and tempering at 480–540°C, best property balance.
1060 – 1080°C — high temperature range, for maximum secondary hardening effect, but increased distortion risk.
For deep cryogenic treatment: hardening is normally performed within 1010–1040°C
Holding time: After temperature equalization, hold for 30 minutes per 25mm of section thickness
Quenching media:
Air (preferred for most sections, especially ≤ 100–150 mm)
Oil (40–70°C) for larger sections or when faster cooling is required.
Warm bath at 500–550°C (martempering) for complex shapes
Hardness after quenching:
From 980–1000°C oil/air quench: approx. 63 HRC.
From 1020–1040°C air quench: 63–65 HRC.
From 1060–1080°C oil/air quench: 64–65 HRC (higher residual austenite content)

Stress relieving

Perform after rough machining or heavy stock removal to reduce the risk of distortion during final heat treatment
Heat carefully to 650°C (approximately 650–700°C range acceptable)
Hold at temperature for 1 – 2 hours (or 2 hours per 25mm section thickness)
Furnace cool to approximately 500°C, then air cool, or cool in still air
This operation is performed to reduce distortion during hardening

Tempering

Temper immediately after the workpiece cools to hand-warm temperature (approx. 50–70°C). Avoid delaying tempering. For air-quenched parts, tempering should begin no later than 2–4 hours after quenching
Number of tempers: Minimum 2 times. Three tempers are recommended for applications requiring secondary hardening or maximum dimensional stability. Double tempering is mandatory for tempering in the secondary hardening range (480–540°C)
Holding time: Soak for 1 hour per 20mm of section thickness (minimum 2 hours per cycle)
Cooling method: Air cool after each tempering cycle (must cool to room temperature before next cycle). Rapid cooling after final tempering improves dimensional stability
Tempering temperature selection:
150 – 200°C (低温回火) — Highest hardness (61–64 HRC) with excellent wear resistance, suitable for cold forming, cutting tools, and shearing blades.
250 – 300°C — intermediate range; reduced hardness (approx. 58–60 HRC), increased toughness.
480 – 540°C (高温回火 / 二次硬化区间) — Secondary hardening range, hardness 58–62 HRC with improved high-temperature strength and thermal stability. Recommended for hot work-like applications or when combined with nitriding/coating.
540 – 600°C — hardness drops significantly (approx. 45–50 HRC), used for specialized applications requiring high toughness

Why Choose NSPM as Your D2 Tool Steel Supplier

Source Direct

Direct mill cooperation ensures stable supply, competitive pricing, and consistent quality. Global resource integration and strong supply chain management guarantee reliable material sourcing and long-term availability.

Stock Ready

50,000+ tons inventory across 11 warehouses enables fast delivery. Flexible cutting, short lead times, and ready stock support urgent demands and improve customers’ production efficiency.

Expert Team

600+ professionals, including R&D specialists and technical engineers, provide application-driven support. Fast response and deep tooling knowledge ensure accurate solutions for diverse industrial needs.

Fully Inspected

Strict quality control system with full traceability, UT testing, and heat treatment records. Certified standards (ISO, CE) ensure every material meets high-performance and reliability requirements.

Full-Chain Machining

From steel supply to precision machining, heat treatment, and equipment manufacturing, NSPM offers integrated solutions that enhance accuracy, efficiency, and overall tooling performance.