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T: +86-0731-85185770
E: enquiry@qilumetal.com
E: enquiry@qilumetal.com
No. 18 Xiangfu Middle Road,Yuhua District, Changsha City
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42CrMo4 / 1.7225 is the most commonly used alloy steel belongs to European standard EN10083-3 and EN10250-3. It could be used in many different industries, such as petrochemical engineering, machining and manufacturing, aerospace and automobile industry etc, so you could find its equivalent steel from different country standard, such as ASTM 4140 from American standard ASTM A29/A29M, SCM440 from Japanese standard JIS G4105, 42CrMo from Chinese standard GB/T1299, 708M40/EN19 from British standard BS970.
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4140
Qilu
AISI 4140 steel is a chromium-molybdenum alloy steel widely used for shafts, gears, bolts, spindles and other high-stress machinery parts. We supply 4140 QT alloy steel in multiple bar forms, including 4140 round bar, 4140 steel bar and forged bar, for machining, heat treatment and industrial component manufacturing.
SAE 4140 steel is a commonly used equivalent designation in North American sourcing. This grade is also associated with 42CrMo4 / 1.7225 and SCM440. For buyers looking for stable material performance and flexible supply, we offer hot rolled, cold drawn and forged sizes with reliable chemistry, consistent mechanical properties and cut-to-length service.
AISI 4140 (equivalent to DIN 42CrMo4 1.7225, JIS SCM440, and BS 708M40) is a high-performance quenching and tempering alloy steel widely recognized for its exceptional mechanical properties. As a key member of the Cr-Mo steel family, it features a carbon content of 0.38-0.45%, which, when combined with chromium (0.8-1.2%) and molybdenum (0.15-0.30%) additions, delivers a balanced blend of strength, toughness, and wear resistance.
This alloy steel undergoes strict quenching and tempering (QT) processes. Its versatility is further enhanced by its compatibility with various manufacturing processes, including forging, machining, and heat treatment, ensuring consistent performance in both small components and large structural parts.
The carefully calibrated chemical makeup of AISI 4140 and its equivalents ensures optimal performance. Key elements include:
Grade | C | Si | Mn | Cr | Mo |
AISI 4140 | 0.38-0.43 | 0.15-0.35 | 0.75-1.00 | 0.8-1.1 | 0.15-0.25 |
DIN 42CrMo4 1.7225 | 0.38-0.45 | 0.4Max | 0.6-0.9 | 0.9-1.2 | 0.15-0.30 |
JIS SCM440 | 0.38-0.43 | 0.15-0.35 | 0.6-0.85 | 0.9-1.2 | 0.15-0.30 |
This composition minimizes impurities (phosphorus ≤ 0.035%, sulfur ≤ 0.04%), reducing brittleness and improving structural integrity.
After QT treatment, AISI 4140 exhibits impressive mechanical performance, varying slightly with size:
Size Range | Tensile Strength | Yield Strength | Elongation |
d≤16mm / t≤8mm | 1100-1300 Mpa | 900 Mpa Min | 10% Min |
16＜d≤40mm / 8＜t≤20mm | 1100-1200 Mpa | 750 Mpa Min | 11% Min |
40＜d≤100mm / 20＜t≤60mm | 900-1100 Mpa | 650 Mpa Min | 12% Min |
These properties make it ideal for load-bearing components requiring both strength and ductility.
AISI 4140 responds well to various heat treatments, allowing customization for specific needs:
· Quenched and Tempered (+QT): Achieves a hardness range of HRC28-32 (common for general applications).
· Flame/Induction Hardening: Reaches 53 HRC for high-wear surfaces.
· Soft Annealed (+A): Reduces hardness to HB241 Max for easier machining.
It is available in multiple forms to suit manufacturing needs:
· Cold drawn bars: Φ3-Φ80mm, length 6000-9000mm
· Hot rolled bars: Φ16-Φ310mm, length 6000-9000mm
· Hot forged bars: Φ100-Φ1200mm, length 3000-5800mm
4140 Steel Bar, Round Bar and Forged Bar Supply
We supply AISI 4140 steel in hot rolled bar, cold drawn bar and hot forged bar conditions. If you are looking for 4140 round bar or 4140 steel round bar for shafts, gears, pins, studs or tooling parts, we can match size range and heat treatment requirements for machining and industrial use.
4140 steel bar / round bar: cold drawn Φ3–Φ80 mm
4140 round bar: hot rolled Φ16–Φ310 mm
4140 forged alloy steel bar: hot forged Φ100–Φ1200 mm
Supply condition: annealed, normalized or 4140 QT according to project needs
AISI 4140 is a staple in automotive manufacturing, used for:
· Crankshafts and connecting rods (withstanding high rotational stress).
· Transmission gears (resisting wear from constant meshing).
Its high strength-to-weight ratio makes it suitable for:
· Aircraft engine components and landing gear parts (supporting heavy loads during takeoff/landing).
· Missile and drone structural elements (withstanding extreme pressure).
Common applications include:
· Machine tool spindles and shafts (maintaining precision under high torque).
· Mining crusher gears and conveyor couplings (resisting abrasion from debris).
While both are Cr-Mo alloy steels, DIN 42CrMo4 1.7225 has a slightly wider carbon range (0.38-0.45% vs. 0.38-0.43% for AISI 4140) and higher molybdenum content (0.15-0.30% vs. 0.15-0.25%), leading to marginally better hardenability.
Weldability is limited due to its carbon content (≈0.42%). Pre-heating (to 200-300°C) and post-weld tempering are recommended to reduce cracking risks.
We maintain large stocks of hot rolled bars (Φ16-Φ310mm) and forged bars (Φ310-Φ550mm). For specific sizes, contact our sales team for real-time updates.
Q: Is SAE 4140 steel the same as AISI 4140 steel?
A: SAE 4140 steel and AISI 4140 steel are commonly used equivalent designations for the same chromium-molybdenum alloy steel grade in engineering and commercial sourcing.
Q: What does 4140 QT mean?
A: 4140 QT means AISI 4140 steel supplied in quenched and tempered condition. This heat treatment improves strength, toughness and wear resistance for demanding machinery components.
Q: Is ASTM 4140 the correct name?
A: Many buyers use ASTM 4140 as shorthand, but a more precise description is AISI/SAE 4140 steel supplied to the applicable ASTM bar specification, such as ASTM A29/A29M, depending on order requirements.
