Alloy Steel 40CrNiMoA Round Bar
➡️ UNS G43400 | AISI 4340 | EN 1.6582 | ASTM A29
➡️ ASTM, EN, JIS & International Standards
➡️ Supply Conditions
➡️ Multiple Diameters & Supply Lengths
➡️ Global Export & International Delivery
Country of Origin:
Europe, Japan, USA
Material Type:
Alloy Steel
UNS Number:
G43400
Wr. No.:
1.6582
MTC Available:
EN 10204 3.1
Product Description for Alloy Steel 40CrNiMoA Round Bar
Alloy Steel 40CrNiMoA Round Bar is a high-grade nickel-chromium-molybdenum alloy structural steel to the Chinese standard GB/T 3077. The letter A shows that it is a high-quality grade with tighter phosphorus and sulfur limits than the normal grade.
The steel contains about 0.37–0.44% carbon, 0.60–0.90% chromium, 1.25–1.65% nickel and 0.15–0.25% molybdenum. It is broadly similar to the American AISI 4340 and the Japanese SNCM439, though the chemistry is not identical.
The combination of nickel, chromium and molybdenum gives high hardenability and a very good balance of strength and toughness after quenching and tempering. The steel keeps good impact toughness at low temperature and has good fatigue strength.
40CrNiMoA bars are produced hot rolled or forged, annealed or quenched and tempered, and finished by peeling or turning. The high carbon equivalent means welding needs careful preheat and post-weld heat treatment.
Common applications include heavy-duty shafts, crankshafts, gears, high-strength bolts, turbine shafts, aircraft landing gear parts and other highly stressed components in machinery, power generation and transport. It is widely used in Chinese standards-based projects and export supply where a 4340-type steel is required. The letter A marks high quality, with phosphorus and sulfur each held to 0.020% maximum, which improves fatigue life in rotating shafts. Chinese aerospace, defence and mining suppliers use the grade widely. It is often compared with AISI 4340, SNCM439 and 36CrNiMo4, but its nickel content is lower than in 4340, so any substitution should be checked against the design. Forged blanks for large shafts are also available on request.
Common Applications of Alloy Steel 40CrNiMoA Round Bar
➡️ Machined shafts, spindles, valve stems, pump sleeves and pins for food, beverage, dairy and pharmaceutical equipment, where the passive chromium oxide film resists both product acids and caustic clean-in-place chemicals.
➡️ Fasteners, studs, bolts, threaded rod and anchor components produced from bar stock, chosen for corrosion resistance combined with the ductility needed for cold heading and thread rolling.
➡️ Chemical, water treatment and general process plant parts such as agitator shafts, flange blanks, nozzles and support components handling water, steam and mildly corrosive media free of significant chlorides.
➡️ Architectural and structural hardware including handrail stanchions, balustrade fittings, tension rods and bollards, where a bright ground or polished bar finish provides both appearance and low maintenance.
International Equivalent Grade for 40CrNiMoA Round Bar
Standard
Country / Region
Grade
UNS
USA
UNS G43400 / UNS G98400
AISI / SAE / ASTM
USA
4340 / 9840
DIN / EN
Europe
1.6582 (34CrNiMo6) / 1.6511 (36CrNiMo4)
JIS
Japan
SNCM439
GB/T 3077
China
40CrNiMoA
KS
South Korea
SNCM439
GOST
Russia
40KhN2MA (40ХН2МА)
Technical Specification for Alloy Steel 40CrNiMoA Round Bar
Specification
Value
Unit
Material
Alloy steel
-
Grade
40CrNiMoA
-
Standard
GB/T 3077
-
Product Form
Round bar (hot rolled, forged or bright)
-
Diameter (supply range)
10–500
mm
Length (random)
3–6
m
Manufacturing Process
Hot rolled or forged, optional peeling, turning, cold drawing or grinding
-
Production Route
EAF or BOF + ladle refining + vacuum degassing
-
Surface Finish
Black, shot blasted, peeled, turned, cold drawn or ground
-
Heat Treatment / Delivery Condition
Annealed or quenched and tempered as ordered
-
Tolerance Standard
GB/T 702 (hot rolled bars) or GB/T 908 (forged bars), or as agreed
-
Carbon Equivalent CEV (IIW, calculated from mid-range analysis)
≈ 0.8
-
Density
7.85
g/cm³
Thermal Conductivity at 20°C
42
W/m·K
Coefficient of Thermal Expansion 20–100°C
11.5
µm/m·K
Specific Heat at 20°C
460
J/kg·K
Modulus of Elasticity at 20°C
210
GPa
Magnetic Properties
Ferromagnetic
-
Testing / Inspection
Chemical analysis, hardness, tensile and impact where specified, UT (EN 10308 / SEP 1921 / ASTM A388), grain size, Jominy on request
-
Certification
EN 10204 3.1 mill test certificate (3.2 on request)
-
Technical Specifications
Get the key technical specifications for Alloy Steel 40CrNiMoA Round Bar
Alloy Steel 40CrNiMoA Round Bar is ordered to GB/T 3077, the Chinese standard for alloy structural steel. Hot rolled bar sizes and tolerances follow GB/T 702, and forged bars follow GB/T 908.
The standard mechanical properties are measured on a 25 mm test blank after quenching at about 850°C in oil and tempering at about 600°C. Real 40CrNiMoA bars of larger size will show lower values than the 25 mm blank.
Bars are usually supplied annealed for machining, with a maximum hardness set by the standard. They may also be supplied quenched and tempered.
The carbon equivalent is high, so welding requires preheat and post-weld heat treatment. Physical data for 40CrNiMoA are reference values. Ultrasonic testing and third-party inspection can be ordered.
GB/T 3077 was revised in 2015. Some buyers still quote older editions, so state the edition on the order. The standard applies to bars up to 250 mm. Its table values apply to bars up to 80 mm, and for 80–250 mm bars it allows elongation, reduction of area and impact energy to fall by set amounts, so large bars should be checked against these reduced limits. For aerospace and defence work, orders often add vacuum degassing, low hydrogen, micro-cleanliness and ultrasonic testing requirements. Delivery hardness in the annealed condition is limited to 269 HBW, which is suitable for rough machining before heat treatment.
Chemical Composition for Alloy Steel 40CrNiMoA Round Bar
Element
Symbol
Min
Max
Unit
Carbon
C
0.37
0.44
%
Silicon
Si
0.17
0.37
%
Manganese
Mn
0.50
0.80
%
Phosphorus
P
-
0.020
%
Sulfur
S
-
0.020
%
Chromium
Cr
0.60
0.90
%
Nickel
Ni
1.25
1.65
%
Molybdenum
Mo
0.15
0.25
%
Chemical Composition
View the chemical composition and applicable material limits for 40CrNiMoA Round Bar
The table shows the GB/T 3077 limits for 40CrNiMoA. The high-grade “A” limits phosphorus and sulfur to 0.020% each.
Carbon at 0.37–0.44% gives high hardness and strength after quenching. Nickel at 1.25–1.65% improves toughness, especially at low temperature, and adds hardenability.
Chromium at 0.60–0.90% raises hardenability and strength. Molybdenum at 0.15–0.25% increases hardenability and reduces temper embrittlement, which is important in Ni-Cr steels.
Silicon and manganese act as deoxidisers and add some strength. The low phosphorus and sulfur limits improve toughness and fatigue strength. Nickel at 1.25–1.65% is lower than in AISI 4340, which has 1.65–2.00%. Chromium at 0.60–0.90% is lower than in 34CrNiMo6, which has 1.30–1.70%. This means 40CrNiMoA has good but not identical hardenability compared with these grades. The Japanese grade SNCM439 is closer, with nickel of 1.60–2.00% and chromium of 0.60–1.00%. Silicon at 0.17–0.37% and manganese at 0.50–0.80% act as deoxidisers and add a little hardenability. The high-grade limits of 0.020% for phosphorus and sulfur reduce temper embrittlement and improve fatigue life, which matters in rotating shafts and landing gear parts. Copper and residual elements are also limited by the standard.
Mechanical Properties for Alloy Steel 40CrNiMoA Round Bar
Mechanical Property
Value
Unit
Tensile Strength Rm (GB/T 3077, 25 mm blank, Q&T)
≥ 980
MPa
Yield Strength ReL (GB/T 3077, Q&T)
≥ 835
MPa
Elongation A (GB/T 3077, Q&T)
≥ 12
%
Reduction of Area Z (GB/T 3077, Q&T)
≥ 55
%
Impact Energy KU2 (GB/T 3077, Q&T)
≥ 78
J
Hardness (annealed or high-temperature tempered)
≤ 269
HBW
Mechanical Properties
Check the key mechanical properties and performance requirements of 40CrNiMoA Round Bar
The values shown are GB/T 3077 minimum requirements for 40CrNiMoA measured on a 25 mm test blank after quenching at about 850°C in oil and tempering at about 600°C. Impact energy is measured with a U-notch specimen (KU2).
The steel combines high strength with high toughness. Its high hardenability means larger sections still reach good core properties, although values fall as size increases.
In the annealed condition, hardness is limited to 269 HBW for machining. For large parts, the required properties at the actual section should be agreed and confirmed on the mill certificate. GB/T 3077 requires 40CrNiMoA to reach tensile strength of at least 980 MPa, lower yield strength of at least 835 MPa, elongation of at least 12%, reduction of area of at least 55% and U-notch impact energy of at least 78 J on the 25 mm test blank. The high reduction of area and impact values show that the steel keeps good ductility at high strength. Note that KU2 impact values cannot be directly compared with Charpy V-notch values from EN or ASTM standards. If a customer needs V-notch results, add them to the order with the test temperature.
Dimension / Sizes for Alloy Steel 40CrNiMoA Round Bar
Dimension / Size
Value
Unit
Available Diameter Range (supply capability)
10–600 (forged sizes on request)
mm
Standard Length (random)
3–6
m
Custom / Cut-to-Length
Available on request
-
Diameter Tolerance
GB/T 702 (hot rolled) or GB/T 908 (forged), or as agreed
-
Length Tolerance
Per ordered standard or as agreed (commonly +50 / -0 mm for cut lengths)
-
Straightness Tolerance
Per GB/T 702 / GB/T 908 or as agreed
-
End Condition
Saw cut square, chamfered or as ordered
-
Surface Finish
Black (as rolled or forged), shot blasted, peeled, rough turned, cold drawn, centreless ground
-
Dimensions & Sizes
Explore available diameters, lengths, and dimensional requirements for 40CrNiMoA Round Bar
Pricing for Alloy Steel 40CrNiMoA Round Bar
Round Bar Prices are generally quoted per kilograms or meters tonnes and can fluctuate with the global raw material and market prices. The final price will depend on a variety of factors, including the grade size, diameter, length, surface finish, the quantity and whether the bars are cut to length or in standard lengths.
For smaller quantities, we can also quote per metre or per piece basis once the required dimensions have been confirmed. Container-loads or orders that are larger in size are typically priced per tonne, based upon the specifications required and the supply conditions.
Please provide your desired dimensions, grades, length number, and end for a current quote including the lead time applicable and details for certification.
Pricing
Get current Alloy Steel 40CrNiMoA Round Bar pricing based on size, quantity, grade, finish, and delivery requirements.
Why Choose Us
Euro Steel Bars is an international distributor, stockist and exporter of stainless round steel bars that cover carbon, stainless alloy, special grades. We stock a variety of sizes and grades. We guarantee every order with mill test certificates as well as full quality-assurance documentation. Our name speaks to our roots: European-sourced materials that is backed by the certificates and rigor that buyers from Asia as well as the Gulf and Africa are looking for.
Each bar we deliver is accompanied by EN 10204 3.1 mill test certificates as well as complete documentation of quality, so what you receive corresponds to what’s written in the documents. We carry a selection of sizes and grades ready for transport, and cut length upon the request of customers, which results in quicker lead times, whether you’re ordering just a one-off spec or a complete project tonnage.
We operate an actual wholesale business that is that is supported with an internationally-operated supply chain therefore we are able to serve fabricators sourcing one grade the same way in the same way as an EPC contractor who is placing a large order. Our clients include manufacturers, fabricators EPC construction companies, engineers oil and gas projects as well as construction companies. we design our inventory as well as documentation to show what buyers need to bring projects forward.
Our customers trust us across Qatar, Oman, Bahrain, Kuwait, Jordan, Malaysia, Singapore, Thailand, Taiwan, Turkey, Italy and South Africa. If you’re looking to source an Gulf energy project, or a construction project within Southeast Asia, you get the same quality of certified material, the exact documentation, and the exact delivery procedure.
Frequently Asked Questions
Should I choose 40CrNiMoA or 42CrMo4?
Is 40CrNiMoA the same as AISI 4340?
What does the letter A mean in 40CrNiMoA?
What heat treatment is used for 40CrNiMoA?
How is 40CrNiMoA heat treated, welded and machined?
What are the limits of 40CrNiMoA?
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