4337 34CrNiMo6 1.6582 SNCM439 817M40 Engineering Alloy Steel

Product Overview

34CrNiMo6 (also designated as 1.6582 under European standards) is a high-performance alloy structural steel compliant with EN 10083-3 and EN 10250-3. Renowned for its exceptional comprehensive mechanical properties after quenching and tempering (QT) treatment, this chromium-nickel-molybdenum alloy steel offers a unique combination of high strength, superior toughness, excellent fatigue resistance, and impact resistance. It is widely trusted in critical applications across heavy machine building, energy engineering, aerospace, automotive manufacturing, mold production, shipbuilding, and construction machinery industries—specifically for crafting highly loaded components that demand uncompromising performance. You can find the equivalent steel grades in various national standards, such as the American standard ASTM 4337 (ASTM A29/A29M), the Japanese standard SNCM439/SNCM8 (JIS G4105) and the British standard 817M40 (BS 970).

34CrNiMo6 is a series of chromium-nickel-molybdenum steels with a carbon content of 0.30-0.38%. After quenching treatment (QT), excellent comprehensive mechanical properties can be obtained, such as high strength, high toughness, good fatigue strength and impact resistance. 34CrNiMo6 has excellent hardenability and comprehensive properties and is commonly used in the manufacture of high-load gears, shafts, connecting rods, crankshafts and other critical components requiring high strength and toughness.

This steel grade has well-established equivalent standards globally, ensuring compatibility and interchangeability in international projects:

Country	USA	Europe	British	Japan
Standard	ASTM A29	EN10083-3	BS970-3	JIS G4105
Grade	4337	34CrNiMo6/1.6582	817M40	SNCM439

Product Features

Chemical Composition (%) of 34CrNiMo6

The precise chemical makeup of 34CrNiMo6 and its equivalent grades is tailored to deliver optimal mechanical performance, with strict controls on impurities. Each element plays a critical role in enhancing the steel’s properties: carbon boosts strength and hardness; chromium improves corrosion resistance and hardenability; nickel enhances toughness and ductility; molybdenum increases wear resistance and high-temperature stability; while silicon and manganese refine the grain structure and improve processability.

Grade	C	Si	Mn	P	S	Cr	Mo	Ni
4337	0.30-0.40	0.20-0.35	0.60-0.80	0.035Max	0.040Max	0.70-0.90	0.20-0.30	1.65-2.00
34CrNiMo6/1.6582	0.30-0.38	0.4Max	0.50-0.80	0.025Max	0.035Max	1.30-1.70	0.15-0.30	1.30-1.70
817M40	0.36-0.44	0.10-0.40	0.45-0.70	0.035Max	0.040Max	1.00-1.40	0.20-0.35	/
SNCM439	0.36-0.43	0.15-0.35	0.60-0.90	0.030Max	0.030Max	0.60-1.00	0.15-0.30	1.60-2.00

Mechanical Properties of 34CrNiMo6

1. Quenching and Tempering (QT) Steel (per EN 10083-3)

Mechanical performance varies slightly by cross-sectional size, with consistent reliability across all ranges. The data below reflects the steel’s behavior under tensile stress, ensuring it meets the demands of high-load applications:

Size range	Tensile strength	Yield strength	Alongation	Area of reduction	Impact value At RT/J
d≤16 t≤8	1200-1400Mpa	1000Mpa Min	9% Min	40% Min	/
16＜d≤40 8＜t≤20	1100-1300Mpa	900Mpa Min	10% Min	45%Min	45J Min
40＜d≤100 20＜t≤60	1000-1200Mpa	800Mpa Min	11% Min	50%Min	45J Min
100＜d≤160 60＜t≤100	900-1100Mpa	700Mpa Min	12% Min	55%Min	45J Min
160＜d≤250 100＜t≤160	800-950Mpa	600Mpa Min	13% Min	55%Min	45J Min

2. Open Die Forgings (per EN 10250-3)

Forged 34CrNiMo6 maintains excellent strength and toughness in both longitudinal (L) and transverse (Tr) directions, making it suitable for large, complex components that require uniform performance:

Size range	Tensile strength	Yield strength	Alongation		Impact value at RT/J
			L	Tr	L	Tr
d≤160	800Mpa Min	600Mpa Min	13% Min	9% Min	45J Min	22J Min
160＜d≤330	750Mpa Min	540Mpa Min	14% Min	10% Min	45J Min	22J Min
330＜d≤660	700Mpa Min	490Mpa Min	15% Min	11% Min	40J Min	20J Min

Test Piece Sampling Requirements:

• For QT steel (EN 10083-1): Samples taken 12.5mm below the heat-treated surface to ensure representation of the core material.

• For open die forgings (EN 10250-1): Samples taken 4/T below the heat-treated surface (20mm min, 80mm max) and t/2 from the end (t = equivalent thickness of the forging’s ruling section) to capture accurate mechanical properties.

Custom sampling can be agreed upon in the buyer-seller contract to align with specific project needs.

3. Surface Hardness & Hardenability

34CrNiMo6 offers versatile hardness options through tailored heat treatment, with excellent hardenability for consistent performance across thick sections—critical for components where uniform hardness is non-negotiable.

Heat Treatment	Hardness
Flame or Induction hardening	55-62 HRC
Soft annealed (+A)	≤ 248 HB
Quenched and tempred (+QT)	28-32 HRC(Common Range)

Hardenability Requirements (End Quench Test)

Where the steel is ordered by using the symbols for normal (+H) or restricted (+HL, +HH) hardenability requirements, the hardenability values should apply below:

Distance in mm from quenched end
Distance		1.5	3	5	7	9	11	13	15	20	25	30	35	40	45	50
Hardness In HRC + H	max	58	58	58	58	57	57	57	57	57	57	57	57	57	57	57
	min	50	50	50	50	49	48	48	48	48	47	47	47	46	45	44
Hardness In HRC + HH	max	58	58	58	58	57	57	57	57	57	57	57	57	57	57	57
	min	53	53	53	53	52	51	51	51	51	50	50	50	50	49	48
Hardness In HRC + HL	max	55	55	55	55	54	54	54	54	54	54	54	54	53	53	53
	min	50	50	50	50	49	48	48	48	48	47	47	47	46	45	44

Scatter bands for the Rockwell - C hardness in the end quench hardenability test.

Supply & Tolerance

1. Product Types & Size Ranges

We offer 34CrNiMo6 in multiple forms to suit diverse manufacturing needs, with flexible length options that can be customized for large-scale projects or specialized applications:

Product type	Size range	Length
Hot rolled bar	Φ16-Φ300mm	6000-9000mm
Hot forged bar	Φ140-Φ800mm	3000-5800mm
Hot rolled plate/sheet	T:12-120mm; W:1500-2500mm	2000-5800mm
Hot Forged block	T: 80-800mm; W: 100-2500mm	2000-5800mm

2. Surface Finish & Tolerance

Precision is guaranteed with strict tolerance controls and various surface finish options, ensuring compatibility with downstream machining and assembly processes:

Surface Finish	Turned	Milled	Grinding(Best)	Polished(Best)	Peeled(Best)	Black Forged	Black Rolled
Tolerance	+0/+3mm	+0/+3mm	+0/+0.05mm	+0/+0.05mm	+0/+0.1mm	+0/+5mm	+0/+1mm
Straighness	1mm/1000mm max.					3mm/1000mm max.

3. Stock Availability

We maintain a large monthly stock of hot rolled and forged bars (10,000+ tons) with popular diameters including: 16mm, 18mm, 19mm, 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, 35mm, 38mm, 40mm, 42mm, 45mm, 48mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm, 200mm, 210mm, 220mm, 230mm, 240mm, 250mm, 260mm, 270mm, 280mm.

Stock levels update daily—contact our sales team for real-time availability, bulk pricing, and lead time estimates.

Processing & Heat Treatment Guidelines

1. Forging Process

The forging process optimizes the steel’s grain structure, enhancing its mechanical properties and durability:

• Heat 34CrNiMo6 ingots to 900-1100℃ in a controlled furnace (uniform heating to avoid thermal stress).

• Perform forging operations within the optimal temperature range (850-1050℃) to ensure grain refinement.

• Cool the forged component in sand to ensure uniform internal structure and minimize residual stress (prevents cracking during subsequent heat treatment).

2. Heat Treatment

Customize the heat treatment process to achieve desired mechanical properties, with recommendations tailored to specific applications:

• Soft Annealed: Heat to 650-680℃ → Soak at temperature (2-4 hours, depending on size) → Furnace cool (50-100℃/hour)

• Normalized: Heat to 850-880℃ → Soak at temperature (1-2 hours) → Air cool

• Quenching and Tempering: Heat to 830-860℃ → Soak thoroughly (1-3 hours, ensuring full penetration) → Quench in water (lower end of temp range: 830-845℃) or oil (upper end: 845-860℃) for rapid cooling → Temper at 540-660℃ (2-4 hours) → Air cool

Note: Above temperatures are guidelines—adjust based on component size, desired properties, and specific application requirements. Our technical team can provide customized heat treatment recommendations.

Weldability of 34CrNiMo6

34CrNiMo6 has relatively poor weldability due to its high carbon content (0.30-0.38%) and elevated alloying element levels. Welding may lead to crack formation and brittle microstructures if not properly controlled. To ensure successful welding, follow these best practices:

• Pre-Weld Preparation: Clean the welding area to remove oil, rust, and debris; pre-heat the base material to 150-250℃ (thicker sections require higher pre-heat temperatures) to reduce thermal gradients.

• Welding Consumables: Use low-hydrogen electrodes (e.g., E8018-B2) or flux-cored wires compatible with high-alloy steels to minimize hydrogen-induced cracking.

• Welding Parameters: Maintain low heat input (15-25 kJ/cm) to avoid overheating; use multi-pass welding with controlled interpass temperatures (≤200℃).

• Post-Weld Treatment: Perform stress relief annealing at 550-600℃ for 2-4 hours, followed by slow cooling to reduce residual stress and improve toughness.

• Inspection: Conduct non-destructive testing (NDT) such as ultrasonic testing (UT) or magnetic particle testing (MT) to detect potential cracks.

Applications of 34CrNiMo6

Leveraging its outstanding strength, toughness, and fatigue resistance, 34CrNiMo6 is the material of choice for critical, high-load components in:

1. Heavy Machinery: Gears, shafts, connecting rods, crankshafts, and transmission components for industrial presses, mining equipment, and metalworking machinery.

2. Aerospace: Aircraft landing gears, engine parts (turbine shafts, connecting rods), and drive shafts—where reliability under extreme conditions is mandatory.

3. Automotive: High-performance vehicle transmission shafts, gears, crankshafts, and differential components for luxury cars, racing vehicles, and commercial trucks.

4. Energy Industry: Wind turbine main shafts, gearbox components, and oil/gas drilling equipment parts (drill collars, stabilizers) that withstand harsh environmental conditions.

5. Mold Manufacturing: Large molds, die-casting molds, and precision tooling for plastic injection molding and metal die-casting—offering durability for high-volume production.

6. Shipbuilding: Propeller shafts, rudder shafts, marine gears, and hull structural components for commercial ships, naval vessels, and offshore platforms.

7. Construction Machinery: Excavator and crane transmission parts, hydraulic cylinder rods, and load-bearing structural components that require resistance to wear and impact.

Application Case Study: Wind Turbine Main Shafts

34CrNiMo6 is widely used in wind turbine main shafts (diameter: 300-600mm, length: 3-5 meters) due to its exceptional fatigue resistance and toughness. The QT heat treatment ensures the shaft can withstand cyclic loads from wind turbulence (up to 10^8 load cycles) while maintaining dimensional stability in outdoor environments. Our supplied 34CrNiMo6 forged bars for wind turbine shafts undergo strict quality control, including ultrasonic testing (100% coverage) and mechanical property verification, meeting the requirements of leading wind energy manufacturers.

Quality Control & Certifications

We adhere to strict quality control processes to ensure every batch of 34CrNiMo6 meets international standards and customer expectations:

• Raw Material Inspection: Verify chemical composition of ingots using optical emission spectroscopy (OES) to ensure compliance with grade requirements.

• Process Control: Monitor forging and heat treatment parameters in real-time using advanced temperature sensors and data logging systems.

• Mechanical Testing: Conduct tensile tests, impact tests (Charpy V-notch), hardness tests (Brinell/Rockwell), and fatigue tests on samples from each batch.

• Non-Destructive Testing (NDT): Perform ultrasonic testing (UT) for internal defects, magnetic particle testing (MT) or liquid penetrant testing (PT) for surface defects, and radiographic testing (RT) for critical components.

• Certifications: Provide mill test certificates (MTC) per EN 10204 3.1 or 3.2, including chemical composition, mechanical properties, and NDT results. Our products are also compliant with ISO 9001, CE, and ASTM standards for global acceptance.

Frequently Asked Questions (FAQ)

Q1: What is the difference between 34CrNiMo6 and AISI 4337?

A1: 34CrNiMo6 (European grade) and AISI 4337 (American grade) are equivalent alloy steels with similar mechanical properties. The main difference lies in chemical composition: 34CrNiMo6 has higher chromium content (1.30-1.70% vs. 0.70-0.90% for 4337) and slightly lower nickel content (1.30-1.70% vs. 1.65-2.00% for 4337). Both are suitable for high-load applications and can be interchanged in most projects.

Q2: Can 34CrNiMo6 be used in high-temperature applications?

A2: Yes, 34CrNiMo6 offers good high-temperature stability up to 450℃. For applications exceeding 450℃, we recommend consulting our technical team to adjust heat treatment parameters or consider specialized heat-resistant alloys.

Q3: What is the lead time for custom-sized 34CrNiMo6 products?

A3: Standard stock products can be delivered within 3-7 working days. Custom-sized forgings or plates typically have a lead time of 2-4 weeks, depending on the complexity and quantity. Contact our sales team for exact lead time estimates.

Q4: How to store 34CrNiMo6 to prevent corrosion?

A4: Store the steel in a dry, well-ventilated area; avoid direct contact with moisture or corrosive substances. For long-term storage, apply anti-corrosion oil or wrap the product in moisture-proof film.

Q5: Do you provide technical support for machining 34CrNiMo6?

A5: Yes, our technical team offers comprehensive machining guidelines, including recommended cutting tools, speeds, and feeds. We can also provide support for heat treatment, welding, and application-specific design.

Inquire & Order

Ready to source 34CrNiMo6 (1.6582) or its equivalent grades? Contact our sales team for personalized quotes, stock verification, and technical support. We offer flexible ordering options and reliable global delivery to meet your project timelines.

• Availability: In stock (contact for real-time quantities)

• Minimum Order Quantity: 1 unit (customizable for bulk orders)

• Global Delivery: Shipping to North America, Europe, Asia, Africa, and Oceania via sea, air, or land transport

Qilu Steel is a trusted supplier of high-quality alloy steels, committed to delivering consistent performance, competitive pricing, and exceptional customer service. All products meet international standards and undergo strict quality control inspections.

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