Alloy Steel 4130 Round Bar
➡️ AISI 4130 | UNS G41300 | EN 1.7218
➡️ 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:
G41300
Wr. No.:
1.7218
MTC Available:
EN 10204 3.1
Product Description for Alloy Steel 4130 Round Bar
Alloy Steel 4130 Round Bar is a solid cylindrical bar produced from low-alloy chromium-molybdenum steel grade AISI/SAE 4130 (UNS G41300). Bar is supplied to ASTM A29 / A29M for general requirements and ASTM A322 for hot-wrought alloy steel bars, with cold-finished bar under ASTM A108 and aerospace material typically to AMS 6348 or AMS 6370.
The grade contains approximately 0.30% carbon with 0.80-1.10% chromium and 0.15-0.25% molybdenum. That gives much better hardenability, strength and elevated-temperature performance than plain carbon steel, while the relatively low carbon keeps it weldable. Grade 4130 is widely regarded as the most weldable of the through-hardening alloy steels, and is welded in the normalised condition without preheat in thin sections.
In the normalised condition tensile strength is typically around 670 MPa. After quenching and tempering, strengths of 850-1000 MPa are readily achieved with good ductility and toughness. The grade is also commonly used in the normalised and stress-relieved condition for welded tubular structures.
Bars are supplied hot-rolled, annealed, normalised, or quenched and tempered, in diameters from about 6 mm to 350 mm and lengths of 3 to 6 m. Machinability in the annealed condition is good.
Typical applications include aircraft engine mounts, tubular airframe structures, landing gear parts, motorsport chassis and roll cages, bicycle frames, hydraulic and pneumatic cylinders, gears, shafts, spindles, valve bodies, drilling and wellhead components and pressure vessel parts. Industries served include aerospace, motorsport, oil and gas, defence, machine building and general engineering.
Common Applications of Alloy Steel 4130 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 AS 4130 Round Bar
Standard
Country / Region
Grade
ASTM A29 / A29M
USA
Grade 4130 (UNS G41300)
ASTM A322
USA
Grade 4130 - hot-wrought alloy steel bar
ASTM A108
USA
Grade 4130 - cold-finished bar
SAE J404
USA
4130
AMS 6348 / AMS 6370
USA
4130 bar for aerospace applications
EN 10083-3
Europe / EU
25CrMo4 (1.7218)
BS EN 10083-3
United Kingdom
25CrMo4 (1.7218)
JIS G4105
Japan
SCM430
GB/T 3077
China
30CrMo
KS D 3867
South Korea
SCM430
ISO 683-2
International
25CrMo4
Technical Specification for Alloy Steel 4130 Round Bar
Specification
Value
Unit
Material
Alloy steel
-
Grade
4130 / UNS G41300 / 25CrMo4
-
Product Form
Round bar / rod
-
Standard
ASTM A29 / A29M and ASTM A322
-
Diameter
6 - 350 (available range)
mm
Length
3 - 6 (standard random or fixed)
m
Manufacturing Process
Hot rolled, forged, or hot rolled and cold drawn
-
Production Route
EAF melting with ladle refining, continuous cast or ingot, hot rolling or forging, heat treatment
-
Surface Finish
Hot-rolled black, peeled, rough turned, cold-drawn bright, turned ground and polished
-
Heat Treatment / Delivery Condition
Annealed, normalised, normalised and stress relieved, or quenched and tempered as ordered
-
Annealing Temperature
800 - 845 then furnace cool (typical)
deg C
Normalising Temperature
870 - 900 then air cool (typical)
deg C
Hardening Temperature
845 - 870 followed by oil quench (typical)
deg C
Tempering Temperature
480 - 650 depending on required strength (typical)
deg C
Tolerance Standard
ASTM A29 / A29M and ASTM A108
-
Carbon Equivalent (CEV)
0.62 (typical, IIW formula)
-
Density
7.85 (typical)
g/cm3
Melting Point
1432 - 1510 (approximate)
deg C
Thermal Conductivity
42.7 at 100 deg C (typical)
W/m.K
Coefficient of Thermal Expansion
12.2 at 20 - 100 deg C (typical)
micro-m/m.K
Specific Heat
477 at 50 - 100 deg C (typical)
J/kg.K
Electrical Resistivity
0.223 (typical)
micro-ohm.m
Modulus of Elasticity
205 (typical)
GPa
Magnetic Properties
Ferromagnetic
-
Applicable Testing Standard
ASTM A370, ASTM E8 / E8M, ASTM E23, ASTM E10, ASTM E415
-
Certification / Inspection Documents
EN 10204 Type 3.1 or 3.2 mill test certificate
-
Technical Specifications
Get the key technical specifications for Alloy Steel 4130 Round Bar
Alloy Steel 4130 Round Bar is ordered to ASTM A29 / A29M and ASTM A322 for hot-wrought bar, ASTM A108 for cold-finished bar, or to AMS 6348 and AMS 6370 for aerospace applications where cleanliness, grain size and additional testing are controlled. Where the European system is used, EN 10083-3 covers the equivalent grade 25CrMo4 and does impose mandatory mechanical minima by ruling section, unlike the ASTM bar standards.
Hardening is carried out from 845-870 deg C with an oil quench, followed by tempering between about 480 and 650 deg C. The chromium and molybdenum additions increase hardenability so that sections up to roughly 50-65 mm can be through-hardened with an oil quench.
Grade 4130 is frequently supplied normalised or normalised and stress relieved rather than quenched and tempered, particularly for welded tubular structures such as airframes and roll cages. In this condition the strength is lower but the material is dimensionally stable and easy to weld.
Welding is straightforward compared with other alloy steels. Thin sections up to about 3 mm are commonly welded without preheat, while heavier sections require preheat of 150-260 deg C and post-weld stress relief.
Testing typically includes chemical analysis to ASTM E415, tensile testing to ASTM A370 and E8 / E8M, hardness to ASTM E10 and, where specified, Charpy impact testing to ASTM E23 and ultrasonic examination to ASTM A388.
Chemical Composition for Alloy Steel 4130 Round Bar
Element
Symbol
Min
Max
Unit
Carbon
C
0.28
0.33
%
Manganese
Mn
0.40
0.60
%
Silicon
Si
0.15
0.35
%
Phosphorus
P
-
0.035
%
Sulfur
S
-
0.040
%
Chromium
Cr
0.80
1.10
%
Molybdenum
Mo
0.15
0.25
%
Iron
Fe
Balance
Balance
%
Chemical Composition
View the chemical composition and applicable material limits for AS 4130 Round Bar
Carbon at 0.28-0.33% sets the attainable hardness after quenching. It is kept in the lower medium range, which is the single most important reason for the grade’s good weldability, since a lower carbon content limits the hardness and crack sensitivity of the weld heat-affected zone while still allowing tensile strengths near 1000 MPa after tempering.
Chromium at 0.80-1.10% is the principal alloying element. It raises hardenability by delaying the transformation of austenite to ferrite and pearlite, so a martensitic structure forms with an oil quench instead of the more severe water quench plain carbon steel needs. Chromium also forms stable carbides that improve wear resistance and raise the tempering resistance, allowing higher tempering temperatures without loss of strength.
The 0.15-0.25% molybdenum adds further hardenability and, just as usefully, suppresses temper embrittlement. Without it, slow cooling through the 375-575 deg C range after tempering would allow phosphorus to segregate to prior austenite grain boundaries and reduce toughness sharply. Molybdenum also adds elevated-temperature strength and creep resistance, which is what puts chromium-molybdenum steels into hot service.
The remaining additions are routine. Manganese at 0.40-0.60% adds hardenability and ties up sulphur as manganese sulphide, and silicon at 0.15-0.35% acts as the deoxidiser. Phosphorus and sulphur are held to 0.035% and 0.040% as residuals that reduce toughness.
Mechanical Properties for Alloy Steel 4130 Round Bar
Mechanical Property
Value
Unit
Tensile Strength (annealed)
560 (typical)
MPa
Yield Strength (annealed)
360 (typical)
MPa
Hardness (annealed)
156 - 187 (typical)
HBW
Tensile Strength (normalised)
670 (typical)
MPa
Yield Strength (normalised)
435 (typical)
MPa
Elongation in 50 mm (normalised)
25 (typical)
%
Reduction of Area (normalised)
60 (typical)
%
Hardness (normalised)
197 (typical)
HBW
Tensile Strength (quenched and tempered)
850 - 1000 (typical)
MPa
Yield Strength 0.2% Proof (quenched and tempered)
700 - 860 (typical)
MPa
Elongation in 50 mm (quenched and tempered)
16 (typical minimum)
%
Reduction of Area (quenched and tempered)
45 (typical minimum)
%
Hardness (quenched and tempered)
255 - 302 (typical)
HBW
Modulus of Elasticity
205 (typical)
GPa
Mechanical Properties
Check the key mechanical properties and performance requirements of AS 4130 Round Bar
ASTM A29 / A29M and ASTM A322 define composition, dimensions and quality for Alloy Steel 4130 Round Bar but do not impose mandatory mechanical minima, so the values listed are typical for the stated heat-treated condition. Purchasers requiring guaranteed properties specify the heat treatment condition and the required tensile range, yield strength and, where applicable, impact energy. Where EN 10083-3 is invoked for the equivalent grade 25CrMo4, mechanical minima are mandatory and are tabulated by ruling section.
The delivered condition governs the result. Annealed bar is soft and readily machined. Normalised bar shows around 670 MPa tensile strength with high ductility and is the usual condition for welded tubular structures, since it is dimensionally stable and needs no post-weld requalification of base metal properties. Quenching and tempering gives the highest strength, with the tempering temperature selected to reach the target.
Section size matters. Hardenability allows through-hardening to roughly 50-65 mm with an oil quench, beyond which the core transforms partly to bainite and ferrite, giving lower core strength.
Tempering in the range 250-400 deg C should be avoided because of tempered martensite embrittlement. Testing is carried out to ASTM A370, ASTM E8 / E8M and, where specified, ASTM E23.
Dimension / Sizes for Alloy Steel 4130 Round Bar
Dimension / Size
Value
Unit
Diameter (available range)
6 - 350
mm
Standard Length
3 - 6
m
Custom Length
Cut to length on request
-
Diameter Tolerance (hot-rolled)
Per ASTM A29 / A29M
-
Diameter Tolerance (cold-finished)
Per ASTM A108, h9 / h10 / h11 or as agreed
-
Length Tolerance
Per ASTM A29 / A29M or as agreed
-
Straightness Tolerance
Per ASTM A29 / A29M or as agreed
-
End Condition
Square cut, saw cut, chamfered or as ordered
-
Surface Finish
Hot-rolled black, peeled, rough turned, cold-drawn bright, turned ground and polished
-
Cut-to-Length Availability
Available
-
Dimensional Standard
ASTM A29 / A29M and ASTM A108
-
Dimensions & Sizes
Explore available diameters, lengths, and dimensional requirements for AS 4130 Round Bar
Pricing for Alloy Steel 4130 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 4130 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
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