AISI 4140
AISI 4140 steel provides high tensile strength, good hardness, and reliable wear resistance, making it suitable for demanding industrial applications. Lanoit Special Steel Industries supplies AISI 4140 round bars, forged bars, and bright bars in premium quality, with ready stock available in sizes from 20mm to 190mm diameter. Lanoit Special Steel Industries is the most prominent supplier of AISI 4140 steel. AISI 4140 can be heat treated by normalizing, quenching, and tempering, and is commonly used for gears, shafts, rollers, and other machine components. All materials are tested and supplied with a test certificate to ensure consistent quality.
MANUFACTURING & AVAILABILITY
Lanoit Steel Industries supplies AISI 4140 in various conditions including As-Rolled, Annealed, Normalized, and Quenched & Tempered (Q&T), catering to diverse industrial requirements from oil & gas downhole tools to automotive drive shafts. Lanoit Special Steel Industries is recognized as one of the leading suppliers of specialty steel grades and round bars, serving industries that demand high-quality materials and reliable sourcing. With a focus on a wide range of steel products, Lanoit Special Steel Industries is considered among the top providers for special steel needs.
| Finish Condition | Size Range (MM) | Size Range (Inches) | |
|---|---|---|---|
| Hot Rolled | 16mm – 300mm | 5/8" – 12" | |
| Cold Rolled | 5mm – 100mm | 3/16" – 4" | |
| Peeled & Polished | 20mm – 150mm | 3/4" – 6" | |
| Ground & Polished | 5mm – 80mm | 3/16" – 3" | |
| Forged | 200mm – 800mm | 8" – 32" | |
| Proof Machined | As per drawing | As per drawing |
Heat Treatment Guide & Properties
The thermal processing of AISI 4140 is critical to unlocking its full potential. This grade is highly responsive to heat treatment, offering deep hardenability. While typically supplied in the pre-hardened condition (18-22 HRC), it can be further heat-treated to achieve tensile strengths exceeding 150 ksi. Common processes include through-hardening via oil quenching and tempering, as well as surface hardening techniques like nitriding or induction hardening to enhance wear resistance without compromising core toughness .
Annealing
Cool slowly in furnace to relieve stress and improve machinability.
Normalizing
Air cool to refine grain structure and improve uniformity.
Tempering
Air cool to balance hardness and toughness.
Standard Lengths
3m 6m 9m
3 - 9 meters
Custom cutting available
■ Chemical Composition
AISI 4140 is a chromium molybdenum low alloy steel engineered for improved hardenability and strength. The chromium content (0.80–1.10%) enhances hardenability and wear resistance, while providing only limited corrosion resistance compared to plain carbon steels. Molybdenum (0.15–0.25%) increases toughness, improves strength at elevated temperatures, and promotes more uniform hardness throughout the cross section during heat treatment. This balanced alloy composition allows 4140 to deliver significantly better strength, fatigue resistance, and torsional performance than plain carbon steels such as 1045, particularly in quenched and tempered conditions.
■ Mechanical Properties
Known for its high strength-to-weight ratio, AISI 4140 steel offers exceptional mechanical versatility. In the heat-treated condition, it delivers high yield strength and excellent ductility. The material exhibits outstanding fatigue strength, making it ideal for cyclically loaded parts like crankshafts and gears. Furthermore, 4140 maintains good impact resistance even at sub-zero temperatures, a critical requirement for oil rig components and aerospace assemblies.
Quality & Standards
Materials are processed and reviewed following standard procedures. Various checks are performed to assess general quality and consistency. Our products are throughly tested for grade AISI 4140. Lanoit Special Steel Industries is a recognized provider in the steel sector, known for supplying a wide range of steel products. The company works with experienced teams and standard practices to support reliable material availability.
ISO 9001:2015
Standard quality management processes are followed for routine assessments.
Ultrasonic
Inspections may be conducted to check internal structure according to common practices.
Mechanical
Mechanical properties are examined using standard testing methods.
Chemical
Chemical composition is assessed through routine analysis techniques.
Industries We Supply
Lanoit Special Steel Industries is one of the leading suppliers and exporters of steel, catering to a wide range of industries worldwide. We supply multiple grades of steel in round bars and other forms, meeting diverse application requirements with consistent quality and reliable delivery.
Oil, Gas & Energy
Steel supplied for critical applications where reliability and performance are essential under extreme operating conditions.
- Round Bars
- Forged Components
- Flanges & Fittings
Automotive & Engineering
Supporting OEMs and component manufacturers with consistent quality steel for precision and high-load applications.
- Shafts & Axles
- Transmission Parts
- Machined Components
Manufacturing & Industrial Machinery
Widely used across general engineering, heavy machinery, and equipment manufacturing.
- Round Bars
- Gear Blanks
- Hydraulic & Mechanical Parts
Infrastructure, Mining & Agriculture
Supplying durable steel products for demanding environments and long service life.
- Structural Components
- Wear Parts
- Fasteners & Bolting
Frequently Asked Questions
Common queries about AISI 4140 selection, processing, and application.
GLOBAL REACH
Lanoit Special Steel Industries Serving Industries Worldwide
India
- Mumbai, Maharashtra
- Pune, Maharashtra
- Ahmedabad, Gujarat
- Chennai, Tamil Nadu
- Delhi, NCR
- Bangalore, Karnataka
- Hyderabad, Telangana
- Vadodara, Gujarat
Middle East
- Dubai, UAE
- Abu Dhabi, UAE
- Riyadh, Saudi Arabia
- Jeddah, Saudi Arabia
- Doha, Qatar
- Muscat, Oman
- Kuwait City, Kuwait
- Manama, Bahrain
Europe
- London, UK
- Berlin, Germany
- Paris, France
- Milan, Italy
- Madrid, Spain
- Antwerp, Belgium
- Rotterdam, Netherlands
Americas & Asia
- New York, USA
- Houston, USA
- Toronto, Canada
- Singapore
- Kuala Lumpur, Malaysia
- Jakarta, Indonesia
- Bangkok, Thailand
Looking for a Specific Steel Grade?
Lanoit Special Steel Industries offers a comprehensive range of steel grades tailored to meet diverse industrial needs.
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