JIANGSU MITTEL STEEL INDUSTRIAL LIMITED
| Payment Terms | L/C, T/T |
| Supply Ability | 50000KGS |
| Delivery Time | 7 Days |
| Packaging Details | Export Packing |
| Type | Alloy Steel Bar |
| Shape | Round |
| Surface Treatment | Custom Made |
| Payment Term | 30%T/T Advance + 70% Balance |
| Color | black or bright |
| Material | Carbon Steel, Alloy Steel, Stainless Steel |
| Welding | conventional methods |
| Custom Made | Yes |
| Custom Cycle | 7-15 Days |
| Diameter | 12mm-650mm |
| Origin | China |
| Specification | According to customer requirements |
| Package | Export Standard Package/as Request |
| Brand Name | TSING SHAN |
| Model Number | 4140 42CrMo 42CrMo4 |
| Certification | ISO SGS MTC |
| Place of Origin | China |
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Product Specification
| Payment Terms | L/C, T/T | Supply Ability | 50000KGS |
| Delivery Time | 7 Days | Packaging Details | Export Packing |
| Type | Alloy Steel Bar | Shape | Round |
| Surface Treatment | Custom Made | Payment Term | 30%T/T Advance + 70% Balance |
| Color | black or bright | Material | Carbon Steel, Alloy Steel, Stainless Steel |
| Welding | conventional methods | Custom Made | Yes |
| Custom Cycle | 7-15 Days | Diameter | 12mm-650mm |
| Origin | China | Specification | According to customer requirements |
| Package | Export Standard Package/as Request | Brand Name | TSING SHAN |
| Model Number | 4140 42CrMo 42CrMo4 | Certification | ISO SGS MTC |
| Place of Origin | China | ||
| High Light | AISI 4140 alloy steel round bar ，42CrMo4 hot rolled steel rod ，DIN 1.7225 forged steel bar | ||
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
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.
Company Details
Business Type:
Manufacturer,Distributor/Wholesaler,Agent,Exporter,Seller
Year Established:
1998
Total Annual:
80Millen-100 Millen
Employee Number:
200~500
Ecer Certification：
Verified Supplier
Jiangsu Mittel Steel Industrial Limited is located in Wuxi City, a beautiful city near Shanghai. Wuxi is close to Shanghai (BAO STEEL) ,Zhangjiagang (ZPSS),Ningbo (BAO XIN),KUN SHAN (DKSS), enjoy excellent geographic location and convenient water, land and air transporta... Jiangsu Mittel Steel Industrial Limited is located in Wuxi City, a beautiful city near Shanghai. Wuxi is close to Shanghai (BAO STEEL) ,Zhangjiagang (ZPSS),Ningbo (BAO XIN),KUN SHAN (DKSS), enjoy excellent geographic location and convenient water, land and air transporta...
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