Hot Rolled AISI 4140 4130 Low Carbon Alloy Steel Solid Round Rod 6-600mm 42CrMo 30CrMo Steel Bars with Competitive Price Alloy Steel Bar

• After-sales Service: Online
• Warranty: 1 Year
• Type: Carbon Steel Bar
• Model NO.: AISI 4140 4130
• Standard: AISI, ASTM, GB, JIS, DIN, BS
• Technique: Hot Rolled
• Application: Structural Steel Bar, Tool Steel Bar, Die Steel Bar
• Surface Treatment: Color Coated
• Alloy: Alloy
• Special Use: Mold Steel, Free Cutting Steel, Cold Heading Steel
• Material: A36, S235, S275, DC01, 1045, Gr50, D2, 1066
• Delivery Time: 15-20days
• Length: 1-12m
• Shape: Round Square Flat Hexagon Irregular Bar
• Diameter: 4-800mm
• Transport Package: Seaworthy Packing for Exporting
• Specification: As Requirement
• Trademark: no
• Origin: China
• HS Code: 7301200000
• Production Capacity: 50000ton/Month

Product Description

Product Description

4140 Steel Bar: Complete Technical & Commercial Guide (English)
Quick Overview
AISI 4140 (also known as SAE 4140) is a chromium-molybdenum medium-carbon alloy steel bar defined by ASTM A29/A29M standard. It's globally recognized for its exceptional strength-toughness balance, superior hardenability, and high fatigue resistance, making it the most widely used high-tensile steel for manufacturing critical components across industries. Equivalent to DIN 42CrMo4 (1.7225), JIS SCM440, and GB/T 3077 42CrMo.

1. Basic Information & International Equivalents

Specification	Details
Primary Standard	ASTM A29/A29M (USA), SAE J403
Common Names	4140 alloy steel bar, 4140 quenched and tempered (QT) bar, 4140 chrome-moly bar
International Equivalents	- DIN EN 10083-3: 42CrMo4 (1.7225) (Europe)- JIS G4053: SCM440 (Japan)- GB/T 3077: 42CrMo (China)- ISO 683-13: 42CrMo4- BS EN 10083-3: EN19 (UK)- AFNOR: 42CD4 (France)
Typical Delivery Forms	Round bar, square bar, flat bar, hexagonal bar, forged bar
Delivery Conditions	Hot-rolled, cold-drawn, normalized, quenched & tempered (QT), annealed

2. Chemical Composition (ASTM A29/A29M)

Element	Content Range (%)	Role
Carbon (C)	0.38-0.43	Primary strength contributor; enables heat treatment
Silicon (Si)	0.15-0.35	Deoxidizer; improves strength and heat resistance
Manganese (Mn)	0.75-1.00	Enhances hardenability and tensile strength
Chromium (Cr)	0.80-1.10	Increases hardness, wear resistance, and corrosion resistance
Molybdenum (Mo)	0.15-0.25	Boosts hardenability, high-temperature strength, and prevents temper brittleness
Phosphorus (P)	≤0.035	Controlled impurity (max 0.030% for premium grades)
Sulfur (S)	≤0.040	Controlled impurity (free-machining grades have 0.08-0.15%)
Nickel (Ni)	≤0.25	Trace element (some grades may have higher content)

3. Mechanical Properties (Quenched & Tempered Condition)

Property	Minimum Value	Typical Range	Test Standard
Tensile Strength (σb)	≥1080 MPa	1080-1200 MPa	ASTM E8/E8M
Yield Strength (σ0.2)	≥930 MPa	930-1050 MPa	ASTM E8/E8M
Elongation (δ5)	≥12%	12-18%	ASTM E8/E8M
Reduction of Area (ψ)	≥45%	45-55%	ASTM E8/E8M
Impact Energy (Akv)	≥63 J (at -20°C, V-notch)	63-80 J	ASTM E23
Hardness	28-32 HRC (QT condition)	28-36 HRC	ASTM E18

Note: Properties vary with section size and heat treatment parameters

4. Key Characteristics & Advantages
Excellent Strength-Toughness Balance: Maintains ductility while delivering ultra-high strength
Superior Hardenability: Can be uniformly heat-treated even in large cross-sections
No Temper Brittleness: Molybdenum addition prevents embrittlement after tempering
High Fatigue Resistance: Ideal for components under cyclic loading (axles, shafts, gears)
Good Low-Temperature Toughness: Performs reliably down to -20°C
Surface Hardenability: Can be induction hardened to 50-55 HRC while retaining core toughness
Improved Machinability: Available in free-machining grades with controlled sulfur content
Weldability: Requires preheating (200-300°C) and post-weld heat treatment to avoid cold cracking

5. Heat Treatment Guidelines

Process	Temperature	Cooling Method	Purpose
Quenching	840-870°C	Oil cooling	Hardening to achieve base strength (55-60 HRC)
Tempering	540-680°C	Air cooling	Reducing brittleness while maintaining strength (28-36 HRC)
Normalizing	850-900°C	Air cooling	Homogenizing structure before final heat treatment
Annealing	680-700°C	Furnace cooling	Softening for improved machinability (HB ≤217)
Induction Hardening	900-950°C	Water spray	Enhancing surface hardness (50-55 HRC) for wear resistance
Stress Relieving	550-600°C	Air cooling	Removing internal stresses after machining/welding

6. Typical Applications
4140 steel bar is the material of choice for highly stressed components requiring strength, toughness, and durability:
Automotive Industry: Crankshafts, connecting rods, drive shafts, gears, steering knuckles, axle shafts
Oil & Gas Industry: Drill pipe joints, wellhead equipment, pressure vessels, downhole tools, offshore platform components
Heavy Machinery: Gearboxes, hydraulic cylinders, machine tool spindles, roller shafts, forging dies
Power Generation: Turbine components, generator shafts, high-pressure steam pipes
Aerospace: Landing gear components, structural parts (after special heat treatment)
General Engineering: Bolts, nuts, fasteners, couplings, sprockets, pinions, and other load-bearing parts

7. Standard Sizes & Supply Range

Bar Type	Dimension Range	Notes
Round Bar	- Hot-rolled: Ø5mm - 200mm- Forged: Ø140mm - 900mm (custom up to 3000mm)- Cold-drawn: Ø3mm - 100mm	Most common form; available in precision tolerances
Square Bar	10mm × 10mm - 300mm × 300mm	Used for shafts, keys, and structural components
Flat Bar	Thickness: 5mm - 100mmWidth: 20mm - 300mm	Ideal for wear plates, brackets, and custom fabrication
Hexagonal Bar	Across flats: 10mm - 100mm	Used for bolts, nuts, and precision components
Length	3000mm - 12000mm	Standard length: 6000mm/12000mm; custom lengths available
Surface Finish	Hot-rolled (black), cold-drawn (bright), shot-blasted, or coated	According to customer requirements
Quality Grade	I/II/III (ultrasonic testing available for critical applications)	EN 10160 UT Class II standard for high-integrity components

8. Commercial Product Description Template (For Export)
Product Name: AISI 4140 (SAE 4140) Quenched & Tempered Alloy Steel Round Bar (Equivalent to DIN 42CrMo4/1.7225, JIS SCM440)
Specifications:
Diameter: Ø50mm
Length: 6000mm
Delivery Condition: Quenched & Tempered (QT)
Hardness: 28-32 HRC
Surface Finish: Shot-blasted and oiled
Certification: MTC 3.1 (EN 10204), ISO 9001, ultrasonic test report (EN 10160 Class II)
Key Advantages:
High tensile strength (≥1080 MPa) with excellent toughness balance
Full compliance with ASTM A29/A29M and international equivalents
Stable supply from Shagang/Baosteel mill sources
Custom cutting-to-length, chamfering, and surface treatment services available
Packaging: Seaworthy wooden crates with moisture-proof paper, steel strapping, and end protectors

9. Quotation Inquiry Response Guide (For International Trade)
When responding to 4140 steel bar inquiries, emphasize these value points to differentiate your offer:
Material Certification: Provide MTC (Mill Test Certificate) 3.1, EN 10204 compliance, and ISO 9001 certification
Equivalent Assurance: Clearly state compatibility with 42CrMo4/SCM440 for global acceptance
Quality Control: Highlight ultrasonic testing, chemical composition verification, and mechanical property testing
Supply Capacity: Mention monthly production volume and delivery lead time (typically 3-4 weeks)
Technical Support: Offer free material selection advice and heat treatment recommendations
Custom Solutions: Provide cutting-to-length, chamfering, threading, and surface treatment services
Cost Efficiency: Highlight competitive pricing for QT bars compared to alternative high-strength materials

• Durable and Versatile Material: Our carbon steel round bars are made from high-quality 1.2714, 1.2738, 1.2311, 1.2312, 4340, and 4130 alloy steel, ensuring excellent durability and versatility for various applications.
• Wide Range of Standards: We cater to global requirements with our products meeting AISI, ASTM, BS, DIN, GB, and JIS standards, ensuring seamless integration into any project.
• Customizable Options: Available in various shapes, including round, square, flat, hexagon, and irregular, our carbon steel round bars can be tailored to meet specific user requirements, such as for a construction project.

 
Q1: Why choose us?
A: Our company, as an internationally experienced and professionalsupplier, has been engaged in steel business for more than ten years. Wecan provide a variety of steel products with high quality to our clients.

Q2: Can you provide OEM/ODM service?
A: Yes. Please feel free to contact us for more details

Q3:What is your terms of payment?
A: 100% T/T advance.
30% T/T and balance against copy of documents.
30% T/T advance, balance L/C at sight.

Q4: Can we visit your factory?
A: Warmly welcome. Once we have your schedule, we will arrange theprofessional sales team to follow up your case.

Q5: Can you provide sample?
A: Yes. Sample is free for regular sizes, but the buyer needs to pay freightcost.

Q6: How long is your delivery time?
A: Regular lead time is 15 to 30 days after receiving deposit.