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18CrNiMo7-6 1.6587 alloy structural steel

18CrNiMo7-6 alloy structural steel offers excellent case-hardening response, high core strength, and outstanding fatigue resistance. With good hardenability and toughness, ideal for heavy-duty gears, shafts, and transmission components.

Standard: ISO 18CrNiMo7-6, DIN 1.6587(17CrNiMo6), GB 17Cr2Ni2Mo
Technique: EAF + LF + VD, forged or hot-rolled, multidirectional forging ratio ≥4, spheroidized annealed
Shape: Round, Flat, Plates, Blocks
Heat treatment: Supplied in annealed condition, hardness ≤229 HBW; normalized or prehardened (QT) 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 ISO 18CrNiMo7-6 in various custom sizes

Chemical Composition (%)

Grade	C	Si	Mn	P (≤)	S (≤)	Cr	Ni	Mo
18CrNiMo7-6	0.15–0.21	≤0.40	0.50–0.90	0.035	0.035	1.50–1.80	1.40–1.70	0.25–0.35
1.6587 (17CrNiMo6)	0.14–0.19	≤0.40	0.50–0.90	0.025	0.035	1.50–1.80	1.40–1.70	0.25–0.35
17Cr2Ni2Mo	0.14–0.19	0.15–0.35	0.40–0.60	0.025	0.025	1.50–1.80	1.40–1.70	0.25–0.35

Main characteristics of 18CrNiMo7-6 Alloy Steel

18CrNiMo7-6 | 1.6587 Alloy Steel applications

18CrNiMo7-6 steel for Wind Turbine Gearbox Component

Exceptional hardenability and fatigue strength ensure reliable, long-life performance under high torque and variable wind loads.

18CrNiMo7-6 steel for Heavy-Duty Axle & Transmission Shaft

Deep surface hardenability and tough core provide outstanding bending fatigue and impact resistance for heavy vehicles and construction machinery.

18CrNiMo7-6 steel for Mining & Cement Mill Gear

Superior wear resistance and contact fatigue strength withstand extreme rolling and sliding stresses in large industrial gear drives.

Our Production Technology For 18CrNiMo7-6 (1.6587 / 17CrNiMo6) Case-Hardening Alloy Steel

EAF
LF
VD
ESR / IQ
Forged or Hot Rolled
Soft Annealed / Normalized / 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)
Grain size stability: 950°C holding for 50–80 hours shall maintain 6–8 grade grain size
Delivery condition options:
Soft annealed (+A): max. 229 HB
Normalized (+N): 140 – 210 HB
Quenched and tempered (+QT): 295 – 406 HB (depending on diameter and tempering)
Mechanical properties as per EN 10084 or ASTM A29 / A322

mechanical properties & heat treatment of 18CrNiMo7-6 steel

Heat temperature	Start forging temperature	Finish forging temperature	Cooling method
1100 – 1200 °C	1050 – 1150 °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. 229 HB
Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling

Hardening

18CrNiMo7-6 is a case-hardening (carburizing) steel. The carburizing process is critical to achieve the desired case hardness and core toughness combination. Normalizing, carburizing, hardening and tempering are the recommended heat treatments to impart the desired microstructure and mechanical properties
Carburizing:
Carburizing temperature: 880 – 980°C (typical: 930–970°C)
Strong carburizing potential: 1.10%
Diffusion carbon potential: 0.65 – 0.85%
Carburizing time: typically 50 – 80 hours for large gears
The carburizing temperature should not exceed 990°C
Core Hardening:
Austenitizing temperature: 830 – 870°C
Quenching media: Water (preferred) or oil
Alternative: From carburizing temperature, cool to 820 – 830°C, then air cool, oil quench, or salt bath quench
Carburizing:
Austenitizing temperature: 780 – 820°C, water quench
Double quenching process is preferred for optimal case microstructure

Stress relieving

Perform after rough machining, heavy stock removal, or welding to reduce residual stresses
Heat to 600 – 650°C
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: 150 – 200°C
Holding time: 1 hour per 25mm of section thickness (minimum 2 hours)
Cooling method: Air cool after tempering
Purpose: Improves plasticity and toughness with a slight reduction in hardness, reducing the risk of grinding cracks

Why Choose NSPM as Your 18CrNiMo7-6 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.