4140 Round Bar – AISI 4140 Alloy Steel Rod, Hex, Flat & Forged Bars
The 4140 round bar is one of the most widely used chromium-molybdenum (chrome-moly) alloy steel bars across engineering, oil & gas, automotive, tooling, and heavy machinery industries. Known for its excellent strength, toughness, wear resistance, and heat treatability, AISI 4140 steel offers a perfect balance between performance and cost.
We supply AISI 4140 round bars, hex bars, flat bars, square bars, hollow bars, threaded rods, and hot-forged alloy steel bars in multiple international standards, including ASTM A29, ASME SA29, SAE 4140, DIN 1.7225, EN 42CrMo4, UNS G41400, and JIS G4105.
Whether you need a 4140 chrome moly steel hot rolled round bar, a hardened 4140 alloy steel hex bar, or a polished 4140 bright bar, this alloy steel grade delivers reliable performance in demanding conditions.
What is AISI 4140 Steel?
AISI 4140 is a medium-carbon, low-alloy steel containing chromium and molybdenum. These alloying elements improve hardenability, tensile strength, fatigue resistance, and impact toughness compared to plain carbon steels.
It is commonly supplied under standards such as:
- ASTM A29 Grade 4140 Steel Rod
- SAE 4140 Round Bar
- ASME SA29 Flat Bar
- DIN 1.7225
- EN 42CrMo4 Steel Hex Bar
- UNS G41400 Hex Bar
- JIS G4105 Black Bar
Because of its versatility, round bar AISI 4140 is used both in as-rolled condition and heat-treated (quenched & tempered) condition.
Forms & Types of 4140 Alloy Steel Bars We Supply
We offer AISI 4140 bars in a wide range of shapes, finishes, and conditions to suit different applications.
4140 Round Bar
The most commonly used form. Available as:
- 4140 Chrome Moly Steel Hot Rolled Round Bar
- AISI 4140 Polished Bar
- Chromoly 4140 Black Bar
- SAE 4140 Round Bar (Heat Treated / Q&T)
4140 Hex Bar
Used where high torque resistance is required:
- 4140 Hex Bar
- UNS G41400 Hex Bar
- Hardened 4140 Alloy Steel Hex Bars
- 42CrMo4 Steel Hex Bar
Flat, Square & Bright Bars
- AISI 4140 Hex / Flat / Bright Bar
- ASTM A29 Grade 4140 Square Bars
- ASME SA29 Flat Bar
- ASTM A29 Grade 4140 Rods
Forged, Hollow & Threaded Bars
- AISI 4140 Hot Forged Alloy Steel Round Bar
- AISI 1.7225 Hollow Bar Supplier in India
- DIN 1.7225 Threaded Rod
Why 4140 Round Bar is So Popular
From our experience supplying alloy steel bars to a wide range of industries, 4140 alloy steel stands out because it offers:
- High tensile and yield strength
- Excellent fatigue resistance
- Good machinability after heat treatment
- Superior wear resistance compared to carbon steel
- Consistent performance under high stress and shock loads
This makes 4140 round bar suppliers a preferred source for manufacturers of shafts, gears, spindles, drill collars, and heavy-duty components.
Standards & Equivalent Grades 4140 alloy steel rods
| Standard | Grade / Designation |
| ASTM | ASTM A29 Grade 4140 |
| ASME | SA29 |
| SAE | SAE 4140 |
| DIN / EN | DIN 1.7225 / EN 42CrMo4 |
| UNS | G41400 |
| JIS | JIS G4105 |
| Common Name | Chromoly 4140 Steel |
Chemical Composition of ASTM A29 Grade 4140 Steel
| Element | Percentage (%) |
| Carbon (C) | 0.38 – 0.43 |
| Manganese (Mn) | 0.75 – 1.00 |
| Chromium (Cr) | 0.80 – 1.10 |
| Molybdenum (Mo) | 0.15 – 0.25 |
| Silicon (Si) | 0.15 – 0.35 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
Mechanical Properties of AISI 4140 Round Bar (Q&T)
| Property | Typical Value |
| Tensile Strength | 850 – 1000 MPa |
| Yield Strength | ≥ 650 MPa |
| Elongation | 12 – 16% |
| Hardness | 197 – 241 HB |
| Impact Toughness | Good |
Heat Treatment of 4140 Alloy Steel
One of the biggest advantages of AISI 4140 round bar is its excellent response to heat treatment. Common heat treatments include:
- Annealing – Improves machinability
- Normalizing – Refines grain structure
- Quenching & Tempering (Q&T) – Increases strength and toughness
- Hardening – Used for wear-resistant components
Because of this flexibility, 4140 chrome moly steel hot-rolled round bar can be customised for specific applications.
Applications of 4140 Round Bar
Based on real-world industrial usage, ASTM A29 4140 steel rod is commonly used in:
- Automotive axles and crankshafts
- Oil & gas drill collars and tool joints
- Hydraulic piston rods
- Gears, pinions, and shafts
- Heavy-duty bolts and threaded rods
- Mold bases and die components
- Structural and mechanical engineering parts
Its strength and toughness make it ideal where carbon steel is not strong enough.
Why Choose Us as Your 4140 Round Bar Supplier?
From years of hands-on experience in supplying alloy steel bars, we understand that customers need more than just material—they need consistency, traceability, and technical support.
When you source 4140 round bar suppliers from us, you benefit from:
- Verified material test certificates (MTC)
- Consistent chemical & mechanical properties
- Wide size range and ready stock
- Custom cutting and heat treatment support
- Export-grade packaging
Our focus is always on delivering steel that performs exactly as expected in real applications. The 4140 round bar remains one of the most reliable and versatile alloy steel products used worldwide. Whether supplied as SAE 4140 round bar, DIN 1.7225 threaded rod, 42CrMo4 steel hex bar, or ASTM A29 grade 4140 square bars, this material delivers outstanding strength, durability, and value.
If you are looking for a trusted source for AISI 4140 hot-forged alloy steel round bar, AISI 4140 polished bar, 4140 alloy steel bars, chromoly 4140 black bar, or hardened 4140 alloy steel hex bars, AISI 4140 round bar, hex bar, flat bar, or hollow bar we are ready to support your requirements with technical expertise and consistent quality.
Global Reach
ASC LLP boasts a robust global presence, committed to delivering unparalleled service and quality to clients around the world. Our dedication to prompt delivery and exceptional customer care sets us apart in the industry. Major corporations across the USA, Europe, Asia, and other regions place their trust in our high-quality 4330V MOD Round Bars. This widespread trust underscores our reputation for reliability and excellence. By consistently meeting and exceeding the expectations of our international clientele, we continue to solidify our position as a leader in the global steel market.
Countries We Export To
UNITED STATES, EUROPE, UK, UAE, SAUDI ARABIA, OMAN, KUWAIT, JORDAN, QATAR, INDONESIA, MALAYSIA, BRAZIL, SPAIN, ITALY, FRANCE, GERMANY, BAHRAIN, SRI LANKA, AZERBAIJAN, AUSTRALIA, AUSTRIA, PHILIPPINES, TURKEY, RUSSIA, IRAN, IRAQ, CANADA, KOREA, JAPAN, YEMEN, FINLAND, ZIMBABWE, HUNGARY, PORTUGAL, VIETNAM, MOROCCO, THAILAND, SOUTH AFRICA, MEXICO, SINGAPORE, GREECE, KUWAIT, POLAND, NEW ZEALAND, SWEDEN, SWITZERLAND, BELGIUM, BHUTAN, BANGLADESH, TAIWAN, ROMANIA, CAMBODIA, KAZAKHSTAN, AFGHANISTAN.
