NSPM8350 4Cr5Mo2V W350 hot work tool steel
8350 tool steel offers outstanding hot toughness, superior thermal-fatigue resistance, and excellent temper stability, making it ideal for die-casting molds, hot-forging die inserts, and extrusion tooling.
- Standard: Ningshing NSPM8350, GB 4Cr5Mo2V, Böhler W350
- Technique: Vacuum refining + Electroslag remelting (ESR) + Special forging process + Ultrafine treatment. Ensures high purity, uniform microstructure, and high isotropy.
- Shape: Round , Blocks
- Heat treatment: Annealing: 840–860 °C, hold 3–4 h, air cool below 500 °C → hardness ≤ 235 HB. Quenching: 1010–1020 °C, oil or air (media 20–60 °C), cool to room temperature → hardness 52–54 HRC. Tempering: 560–620 °C, air furnace, air cool → hardness 45–50 HRC.
- Surface Treatment: Delivered in annealed condition (as-forged / black surface).
- Tolerance: According to Ningshing’s standard supply specification
- MOQ: 1 Ton
We supply NSPM 8350 in various custom sizes
plate
flat
block
round
Chemical Composition (%)
钢种 | C | Si | Mn | Cr | Mo | V | P | S |
NSPM8350 (Ningshing) | 0.35 | 0.30 | 0.50 | 5.10 | 1.85 | 0.55 | ≤0.015 | ≤0.005 |
4Cr5Mo2V (GB/T 1299-2014) | 0.35~0.42 | 0.25~0.50 | 0.40~0.60 | 5.00~5.50 | 2.30~2.60 | 0.60~0.80 | ≤0.020 | ≤0.008 |
W350 | 0.38 | 0.20 | 0.55 | 5.00 | 1.80 | 0.55 | — | — |
Main characteristics of 8350 tool steel
- Outstanding hot toughness ‑ anti‑cracking under cyclic thermal loads
- Superior thermal fatigue resistance ‑ reduces heat checking
- Exceptional temper stability ‑ maintains hardness at high temperatures
- Favorable hot‑wear resistance ‑ extended service life for hot‑work tooling
8350 tool steel applications
8350 steel for Die-Casting Molds
NSPM8350 delivers an exceptional balance of high toughness and thermal fatigue resistance, purpose-built for large, complex high-pressure and low-pressure die-casting molds where resistance to gross cracking is critical.
8350 steel for Hot-Forging Die Inserts
Outstanding impact toughness in heavy sections minimizes premature fracture in medium-to-large hot-forging die inserts, ensuring reliable performance under severe mechanical and thermal shock.
8350 steel for Extrusion Tooling
High hot strength combined with superior wear and crack resistance makes NSPM8350 the preferred choice for critical extrusion tooling components—liners, dies, and stems—under sustained thermal and mechanical loads.
Our Production Technology For NSPM8350 (4Cr5Mo2V / W350) Premium Hot Work Tool Steel
- EAF
- LF
- VD
- ESR
- Special Forging Process
- Ultra-Fine Grain Treatment
- Spheroidizing Annealed
- Machined surface / Peeled
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Quality Control:
Ultrasonic testing (UT) as per SEP 1921 or ASTM A388 (upon request)
Micro Cleanliness as per ASTM E45 — ultra-low inclusion levels (P ≤ 0.015%, S ≤ 0.005%)
Grain size ultra-fine, homogeneous structure - Delivery condition: Soft annealed, hardness ≤ 235 HB
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Product forms:
Forged blocks: 80 – 500 × 300 – 1200 mm
Round bars: Φ60 – 600 mm
mechanical properties & heat treatment of 8350 steel
| Heat temperature | Start forging temperature | Finish forging temperature | Cooling method |
| 1100 – 1150 °C | 1100 – 1050 °C | ≥ 900 °C | Pit, sand, or furnace cooling |
Spheroidizing Annealing
- Spheroidizing annealing is performed to produce a fine, uniform spheroidized carbide microstructure for optimum machinability and to prepare the steel for final hardening
- Annealing temperature 840 – 860°C
- Holding time 3 – 4 hours
- Cooling rate 15°C/h (controlled furnace cooling)
- Cooling method Furnace cool to below 500°C, then air cool to room temperature
- Hardness after annealing ≤ 235 HB
Hardening
- NSPM8350 is a premium hot work tool steel with excellent hardenability. Proper preheating and austenitizing are critical to achieve the desired hardness without cracking. The steel can be quenched in oil or air, providing flexibility for distortion control.
- Pre-heating (recommended) 600 – 850°C (two-stage preheat recommended to reduce thermal stress)
- Austenitizing temperature 1010 – 1020°C
- Holding time 15 – 30 minutes after temperature equalization
- Quenching media Oil (preferred) or Air
- Cooling medium temperature 20 – 60°C
- Cool to Room temperature
- Hardness after quenching 52 – 54 HRC
Stress relieving
- Perform after rough machining, heavy stock removal, or EDM to reduce residual stresses 2. Heat carefully to 600 – 650°C
- Heat carefully to 600 – 650°C
- Hold at temperature for 1 – 2 hours (minimum)
- Air cool after holding
- This operation reduces the risk of distortion during final hardening and improves dimensional stability
Tempering
- Temper immediately after the workpiece cools to handwarm temperature (approx. 50–70°C). Delayed tempering may cause cracking
- Number of tempers: Minimum 2 times. Double tempering is mandatory for this grade to ensure complete transformation of retained austenite and optimal property stability
- Holding time: 2 hours minimum per cycle (or 1 hour per 20mm of section thickness)
- Cooling method: Air cool after each tempering cycle
- Tempering temperature range: 560 – 620°C
- Avoid the range 425 – 550°C to prevent temper embrittlement
Why Choose NSPM as Your 8350 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.
