Español
Türkçe
Français
عربي 
dansk
한국어
Deutsch
Việt Nam
Italiano
日本語
Português
4140 / 42CrMo High Strength Alloy Steel
BRAND: PROMISTEEL
GRADES: AISI 4140, 42CrMo, 42CrMo4 (1.7225), SCM440
SHAPES: Round Bar, Flat Bar, Heavy Plate, Block
DELIVERY CONDITION: Hot Rolled, Annealed, Q+T (Pre-hardened)
HARDNESS: QT Condition: 28-32 HRC; Annealed: ≤217 HB
FEATURE: High Strength, High Fatigue Resistance
APPLICATION: Axles, Drive Shafts, Gears, Drill Collars, Bolts
MOQ: 25 Tons
AISI 4140 (42CrMo) is the world's most versatile and widely used "Chrome-Moly" alloy steel. It is renowned for its excellent balance of strength, toughness, and wear resistance.
Unlike standard carbon steel, the addition of Chromium (Cr) and Molybdenum (Mo) allows 4140 to be heat-treated to a uniform hardness while maintaining high fatigue strength. We supply this material primarily in the Quenched and Tempered (Q+T) condition (usually 28-32 HRC), which allows customers to machine the parts directly without further heat treatment, avoiding distortion risks. It is the material of choice for power transmission parts in automotive, oil & gas, and mining industries.
Product Specifications & Grade Equivalents
We supply high-strength 4140/42CrMo steel meeting global standards, ensuring compatibility for international projects.
Table-1
The universal standard for engineering alloy steel.
International Grade Comparison |
||||
| GB (China) | ASTM / AISI (USA) | DIN / EN (Germany) | JIS (Japan) | ISO |
| 42CrMo | 4140 | 1.7225 (42CrMo4) | SCM440 | 42CrMo4 |
| 35CrMo | 4135 | 1.7220 (34CrMo4) | SCM435 | - |
| 30CrMo | 4130 | 1.7218 (25CrMo4) | SCM430 | - |
Table-2
Molybdenum provides deep hardenability and prevents temper brittleness.
Chemical Composition (Mass Fraction %) |
|||||
| Grade | C | Cr | Mo | Mn | Si |
| 4140 / 42CrMo | 0.38~0.45 | 0.90~1.20 | 0.15~0.25 | 0.60~0.90 | 0.15~0.35 |
| 1.7225 (42CrMo4) | 0.38~0.45 | 0.90~1.20 | 0.15~0.30 | 0.60~0.90 | ≤0.40 |
| SCM440 | 0.38~0.43 | 0.90~1.20 | 0.15~0.30 | 0.60~0.85 | 0.15~0.35 |
Table-3
Huge inventory of large diameter bars and heavy plates.
Supply Range & Formats |
|||
| Product Form | Dimensions (mm) | Delivery Condition | Surface Finish |
| Round Bar | Dia: 16 - 800 | Hot Rolled / Forged / QT |
Black / Peeled / Turned |
| Flat Bar | 20 - 400 x 50 - 1000 | Forged / Milled |
Machined (6-Sides) |
| Plate | Thickness: 10 - 300 | Hot Rolled / QT |
Black / Shot Blasted |
| Block | Custom Cut | Forged | Sawn / Milled |
Key Features and Advantages
- High Hardenability: The Chromium-Molybdenum alloy allows the steel to harden deeply, ensuring uniform strength even in large cross-sections (e.g., 500mm diameter shafts).
- Excellent Fatigue Strength: Ideal for parts subjected to cyclical loads and vibration, such as vehicle axles and drill collars.
- Pre-hardened (QT) Availability: We stock 4140 in the Pre-hardened (28-32 HRC) condition. This eliminates the cost and time of post-machining heat treatment and ensures no warping of the final part.
- Good Machinability: In the annealed or pre-hardened state, it machines well with a good surface finish.
- Impact Toughness: Superior to standard carbon steel (like 1045), resisting fracture under shock loads.
Typical Applications
4140/42CrMo is the "Workhorse" of the engineering world:
Oil & Gas
Drill collars, kelly bars, and sub-sea fasteners (requires strict API standards).
Automotive
Axle shafts, crankshafts, connecting rods, and steering knuckles.
Machinery
Large gears, spindles, conveyor rolls, and high-tensile bolts (Grade 10.9).
Mining
Excavator pins, rock crusher shafts, and hydraulic cylinder rods.
Mold Bases
Often used as a high-strength holder block for plastic molds.
FAQ
Q1: What is the difference between 4140 and 42CrMo?
A1: They are virtually identical. 4140 is the American (AISI) designation, while 42CrMo is the Chinese (GB) designation. Their chemical composition and mechanical properties are interchangeable in 99% of engineering drawings.
Q2: What does "4140 QT" mean?
A2: QT stands for Quenched and Tempered. It means the steel has already been heat-treated to a hardness of usually 28-32 HRC (280-320 HB). You can machine it directly into a finished part without further heat treatment. This is our most popular delivery condition.
Q3: Can 4140 steel be welded?
A3: Yes, but with caution. Due to its hardenability, 4140 is prone to cracking if welded cold. It must be preheated (to approx. 200-300°C) before welding and cooled slowly afterwards. Use low-hydrogen electrodes.
Q4: Is 4140 stronger than 1045 steel?
A4: Yes, significantly. 4140 has much higher tensile strength, yield strength, and fatigue resistance than 1045 carbon steel. 4140 is used when 1045 is not strong enough to prevent bending or breaking.
Hot Tags: 4140 / 42crmo high strength alloy steel, China 4140 / 42crmo high strength alloy steel manufacturers, suppliers
Next
No InformationYou Might Also Like
Send Inquiry