34CrAlNi7-10 1.8550 alloy structural steel
1.8550 alloy structural steel offers excellent nitriding response, superior surface hardness, and enhanced wear resistance. With good tempering stability and core toughness, ideal for high-stress components such as injection screws, extrusion cylinders, and high-load gears.
- Standard: EN 34CrAlNi7-10, DIN 1.8550(34CrAlNi7)
- Technique: EAF + LF + VD, forged or hot-rolled, multidirectional forging ratio ≥4, quenched and tempered (prehardened) for uniform structure prior to nitriding
- Shape: Round, Flat, Plates, Blocks
- Heat treatment: Supplied in quenched and tempered (QT) condition, hardness 26–32 HRC typical; annealed condition available on request
- Surface Treatment: Turned, milled / ground, sawn ends. Black (hotrolled / forged surface) available for large sections
- Tolerance: flat bars & plates thickness: +0.5/-0.0 mm (turned); forged blocks: ±0.2 mm
- MOQ: 1 Ton
We supply DIN 1.8550 in various custom sizes
plate
flat
block
round size range
- Diameter: φ10-1200 mm
Chemical Composition (%)
Grade | C | Si | Mn | P (≤) | S (≤) | Cr | Ni | Al | Mo |
1.8550 (34CrAlNi7-10) | 0.30–0.37 | ≤0.40 | 0.40–0.70 | 0.035 | 0.035 | 1.50–1.80 | 0.85–1.15 | 0.80–1.20 | 0.15–0.25 |
34CrAlNi7 | 0.30–0.37 | 0.20–0.40 | 0.50–0.80 | 0.030 | 0.030 | 1.40–1.70 | 0.70–1.00 | 0.60–0.90 | 0.15–0.25 |
Main characteristics of 1.8550 alloy steel
- Excellent nitriding behavior – forms a hard, wear-resistant surface layer
- High core toughness – resists impact and withstands heavy mechanical loads
- Good tempering stability – retains strength and hardness after heat treatment.
- Superior dimensional stability – minimizes distortion during heat treatment and service
34CrAlNi7-10 | 1.8550 alloy steel applications
1.8550 steel for Precision Nitrided Spindle
Superior surface hardness and fatigue strength after nitriding guarantee long-term precision and wear resistance for machine tool and transmission spindles.
1.8550 steel for Extrusion Screw & Barrel
Good core toughness combined with a hard nitrided case resists adhesive wear and corrosive attack in plastic and rubber extrusion processes.
1.8550 steel for High-Wear Mould Insert
The nitrided layer on 1.8550 delivers outstanding abrasion resistance and dimensional stability for mould inserts subjected to high injection pressures and abrasive resins.
Our Production Technology For 1.8550 (34CrAlNi7-10 / SIQUAL 8550) Nitriding Alloy Steel
- EAF
- LF
- VD
- Forged or Hot Rolled
- Soft Annealed / Quenched and Tempered
- Machined surface / Peeled / Black finish
- 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 (upon agreement)
- Delivery condition options:Soft annealed (+A): max. 248 HBQuenched and tempered (+QT): tensile strength from 800 – 1100 MPa (depending on diameter)
- Mechanical properties as per EN 10085
mechanical properties & heat treatment of 1.8550 steel
| Heat temperature | Start forging temperature | Finish forging temperature | Cooling method |
| 1050 – 1100 °C | 1050 – 1000 °C | ≥ 850 °C | Pit, sand, or furnace cooling |
Annealing
- Annealing temperature: 650 – 700°C
- Hold at temperature for sufficient time (minimum 2 hours, or 2 minutes per mm of section thickness)
- Cool slowly in the furnace
- Hardness after annealing: max. 248 HB
- Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling
Hardening
- 1.8550 is a nitriding steel that is typically supplied in the quenched and tempered condition. If re-hardening is required, the following parameters apply
- Austenitizing temperature: 870 – 930°C.Alternative range: 850 – 900°C
- Holding time: Minimum 30 minutes at temperature
- Quenching media: Oil or water.Oil quenching is preferred for most sections to minimize distortion.Water quenching may be used for larger sections or when maximum hardness is required
- Hardness after quenching: Dependent on section size and quenching medium; typically achieves high hardness prior to tempering
Stress relieving
- Perform after rough machining, heavy stock removal, or other cold working operations to reduce residual stresses
- Heat carefully to 600 – 650°C (below the tempering temperature)
- Hold at temperature for 1 hour per 25mm of section thickness (minimum 2 hours)
- Air cool after holding
- This operation reduces the risk of distortion during final heat treatment and improves dimensional stability
Tempering
- Temper immediately after quenching to avoid cracking
- Tempering temperature:Standard range: 580 – 700°C.Alternative: 570 – 660°C.Hold for a minimum of 1 hour
- Number of tempers: Minimum 1 time; 2 times recommended for critical component
- Cooling method: Air cool after tempering
- Purpose: Achieve the required core strength and toughness while preparing the microstructure for the final nitriding process
Why Choose NSPM as Your 1.8550 alloy 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.
