34CrNiMo6 (1.6582) Steel: Properties and Applications

34CrNiMo6 is a high-strength chromium-nickel-molybdenum alloyed quenched and tempered steel. With the material number 1.6582, this grade is defined in the EN 10083-3 standard. Thanks to its nickel content, it offers high hardenability, excellent toughness and fatigue strength even in large cross-sections. This makes it one of the preferred choices for critical machine parts operating under heavy loads, impact and fluctuating stresses. In this article, you will find the technical properties of 34CrNiMo6, how it differs from 42CrMo4 and 30CrNiMo8, and what to consider when purchasing it.

34CrNiMo6 designation

Each part of the grade name 34CrNiMo6 provides information about the steel’s composition:

• 34: Approximately 0.34% carbon (100 times the carbon content)
• Cr, Ni, Mo: The main alloying elements: chromium, nickel and molybdenum
• 6: Chromium content multiplied by the alloy factor (the factor for chromium is 4; 6 / 4 ≈ 1.5% Cr)

We explain the effects of alloying elements on steel in detail in our article The Effect of Alloying Elements on Steel Structure.

34CrNiMo6 chemical composition

Heat analysis according to EN 10083-3:

34CrNiMo6 mechanical properties (quenched and tempered, +QT)

In quenched and tempered steels, mechanical properties decrease as the cross-section increases. The minimum values by diameter range according to EN 10083-3 are as follows:

These values are significantly higher than those of 42CrMo4 in the same diameter range. For example, in the 40–100 mm range, the minimum yield strength is 650 MPa for 42CrMo4, compared with 800 MPa for 34CrNiMo6.

The nickel difference: Why 34CrNiMo6?

Nickel increases the hardenability of steel and improves toughness, especially at low temperatures. As a result, 34CrNiMo6 offers:

• Uniform structure: More uniform hardness and strength through to the core in large cross-sections.
• Impact resistance: High resistance to impact and shock loads.
• Fatigue strength: Long service life in rotating parts and parts under fluctuating loads.
• Low-temperature safety: Greater safety against brittle fracture at low temperatures.

34CrNiMo6 vs. 42CrMo4 vs. 30CrNiMo8

All three grades are quenched and tempered steels considered for similar applications; the main difference is their nickel content and the resulting hardenability:

As a general rule, 42CrMo4 is an economical and sufficient solution for medium-section, medium-load parts. As cross-sections grow and loads become heavier, 34CrNiMo6 is preferred, while 30CrNiMo8, with higher chromium, nickel and molybdenum content, is chosen for the most demanding applications with the largest cross-sections.

34CrNiMo6 heat treatment

• Soft annealing (+A): Applied to improve machinability.
• Hardening: Oil quenched from approximately 830–860 °C.
• Tempering: Usually carried out in the 540–660 °C range, depending on the target strength.
• Nitriding: Can be applied to quenched and tempered material to provide surface hardness and wear resistance.

In nickel alloyed steels, cooling conditions after tempering should be carefully determined to avoid the risk of temper embrittlement.

34CrNiMo6 applications

Typical applications of 34CrNiMo6 include:

• Large-diameter, heavily loaded transmission shafts
• Crankshafts, connecting rods and axles
• Wind turbine and gearbox gears, pinions
• Power plant and turbine components
• Construction machinery, mining equipment and crane parts
• Defense industry and aerospace supply chain components
• High-strength bolts and fasteners

34CrNiMo6 international equivalents

Grades close to 34CrNiMo6 in different standards are as follows:

Equivalent grades are not identical in chemical composition; in particular, AISI 4340 has different carbon and nickel ranges. For critical parts, the standard specified on the drawing should always be followed.

What to consider when buying 34CrNiMo6

• Delivery condition: Specify +A (annealed) or +QT (quenched and tempered).
• Cross-section and strength: Verify that the target strength is achievable for the section size.
• Inspection: For critical applications, include ultrasonic testing (UT) and internal cleanliness requirements in your request for quotation.
• Production method: Clarify whether forged or rolled material is required based on your design requirements.
• Certification: Request an EN 10204 3.1 certificate with chemical analysis and mechanical test results.

Forged or rolled?

High-alloy steels such as 34CrNiMo6 can be supplied as hot rolled bars or forged bars. Forging densifies the internal structure, especially in large diameters, aligns the grain flow with the part geometry and closes internal voids.

For this reason, forged bars are preferred in applications requiring high reliability, such as very large-diameter shafts and wind turbine and gearbox components. For medium-diameter parts intended for series production, hot rolled bars offer an economical solution.

For critical parts, checking for internal defects with ultrasonic testing prevents costly failures that could occur later.

34CrNiMo6 supply from Uyar Çelik

For alloy grades with limited production in Türkiye, Uyar Çelik offers imported hot rolled alloy steel bars and forged steel bars.

Through our European logistics center in Düsseldorf, we provide reliable and traceable supply of critical grades such as 34CrNiMo6, 30CrNiMo8 and 18CrNiMo7-6.

Frequently asked questions

What is the equivalent of 34CrNiMo6?

Its approximate equivalents are considered to be AISI 4340 and BS 817M40 (EN24); however, their chemical composition ranges are not identical.

Should I choose 34CrNiMo6 or 42CrMo4?

42CrMo4 is usually sufficient for medium cross-sections. For large-diameter parts or parts subject to impact or high fatigue loads, 34CrNiMo6 is the safer choice.

Can 34CrNiMo6 be welded?

Its weldability is limited. When welding is unavoidable, preheating, controlled interpass temperature and post-weld heat treatment should be applied.

Conclusion

34CrNiMo6 is a reliable quenched and tempered steel for heavily loaded critical parts, offering high hardenability, toughness and fatigue strength in large cross-sections thanks to its nickel content. For the right choice, section size, delivery condition, production method and inspection requirements should be evaluated together.

Get a quote for 34CrNiMo6 and other alloy steels: +90 (212) 485 98 98 or visit our contact page.