4340 Chromoly Alloy Steel Seameless Round Tube for High Temperature Service

AISI 4340 seamless chromoly tubing is a medium-carbon, low-alloy steel tube engineered for elevated-temperature applications, offering exceptional strength, toughness, fatigue resistance, and wear properties. It is manufactured by cold drawing or hot pilgering processes to tight tolerances, yielding a smooth surface finish and uniform mechanical properties. Typical dimensions range from 10 mm to 200 mm outer diameter with wall thicknesses of 1 mm to 20 mm, accommodating a broad spectrum of hydraulic, aerospace, oil-and-gas, and mechanical applications. The tubing meets key delivery conditions under ASTM A519, EN 10216-2, JIS G3445, GB/T 8162, and GOST 8732-78 standards, ensuring compatibility with global engineering specifications.

Material Description

AISI 4340 is an ultra-high strength chromoly alloy steel containing nickel, chromium, molybdenum, manganese, and silicon, with a carbon content of 0.38 – 0.43 wt %. Its alloying promotes a fine martensitic microstructure upon quenching and tempering, resulting in yield strengths from 740 MPa up to 1860 MPa and tensile strengths of 860 – 1980 MPa, depending on heat treatment. This composition delivers a hardness range of HRC 24 – 53, excellent creep resistance, and superior crack-arrest toughness at elevated temperatures.

Specifications

• Outer Diameter (OD): 10 mm – 200 mm

• Wall Thickness (WT): 1 mm – 20 mm

• Lengths: Cut to customer requirements (up to 6 m)

• Tolerance: ±0.1 mm OD, ±0.05 mm WT per ASTM A519 precise tubing tolerance

Chemical Composition Comparison

Mechanical Properties Comparison

Key Features

• High Strength & Toughness: Exceptional tensile and yield strengths with good ductility for safety under dynamic loading.

• Elevated-Temperature Performance: Maintains mechanical integrity up to 600 °C in tempered conditions.

• Fatigue & Creep Resistance: Ideal for cyclic and sustained-load service in hydraulic, aerospace, and pressure-vessel components.

• Wear & Impact Resistance: Hardenable surface layer provides abrasion resistance while core retains toughness.

• Precision & Finish: Cold-drawn surface finish with concentricity and roundness tolerances suited for high-precision assemblies.

Applicable Standards

• ASTM A519: Seamless carbon and alloy steel mechanical tubing

• EN 10216-2: Seamless steel tubes for pressure purposes – alloy steels with specified elevated-temperature properties

• JIS G3445 / G4105: Alloy steel tubes for general structural and mechanical purposes

• GB/T 8162: Seamless carbon and alloy steel tubes for general structural purpose

• GOST 8732-78: Seamless steel pipes for general purposes

Application Fields

General Sectors

• Aerospace & Defense

• Oil & Gas Exploration

• Automotive & Heavy Machinery

• Hydraulic & Pneumatic Systems

• Power Generation & Pressure Vessels

Specific Uses

• Hydraulic Cylinder Rods & Shafts: High fatigue life under cycling loads.

• Aircraft Landing Gear & Fasteners: Demanding toughness at sub-zero and elevated temperatures.

• Crankshafts & Gears: Superior wear resistance and surface hardenability.

• Oilfield Drill Collars & Tubing: Sustained load capacity and corrosion resistance in downhole environments.

• Pressure Vessel Components: Reliable performance under pressure and thermal cycling.

Q: Are you trading company or manufacturer ?

A: manufacturer,also can do trading.

Q: How long is your delivery time?

A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock,

it is according to quantity.

Q: Do you provide samples? is it free or extra ?

A: Yes, we could offer the sample for free charge but need pay the cost of freight.

Q: What is your terms of payment ?

A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.

If you have another question, pls feel free to contact with me.

Who We are ?

-------A professional steel pipes materials inventor, manufacturer and solution provider
Torich International Limited is a professional manufacturer and exporter of steel pipes materials. It is an international marketing and sales company specialized in steel tubes, which holds the factories of Seamless Steel Tubes with Carbon and Alloy Steel Grade, Welded Precision Steel Tubes,DOM Steel Tubes, Seamless & Welded Stainless Steel Tubes with Nickel and Alloy Steel Grade.
Our factory was established since 1997, with the name of TORICH INTERNATIONAL LIMITED. The factories’ technicians are of great engineering experience in steel pipe industry for more than 20 years, which are in great command of production technology for Cold Drawing and Cold Rolling. So we have strong technician team and manufacturing capability.

What products we do?

------- Invent and produce various Precision Steel Pipes

Our steel pipes cover the following ranges:
Seamless Precision Steel Pipes

Bearing Steel Tubes
Welded Precision Steel Pipes, with DOM production
Seamless Heat Exchanger Steel Pipe
Seamless Boiler Steel Pipes

Honed Tubes

Hydraulic Cylinder Steel Tubes

Hydraulic Telescopic Cylinder Tubes
Seamless Structural Steel Pipes
Seamless Mechanical Steel Pipes
Seamless Alloy Steel Tubes & Pipes
Seamless Stainless Steel tubes
Welded Stainless Steel Tubes
Seamless Stainless Steel Tubes & Pipes
Welded Stainless Steel Tubes & Pipes
Seamless Carbon Steel Tubes & Pipes
Nickel Alloy Steel Tubes & Pipes

What TORICH do:
1. Producing Steel Tubes
2. Selling both on Domestic and International Market
3. Precisely Targeting Customers’ Requirement- Sourcing the right factory for right products for Customers

Products Application:
Oil Cylinders
Air Cylinder, 
Automotive Cylinder Liners
Boilers, Pressure Vessels
Shell & Heat Exchangers
Jack Lifting
Telescopic Systems
Pneumatic Cylinders
Agricultural Machineries

Size range is: 
O.D. 4-350mm, 
W.T. 0.5-30mm, 
Length: according to customer’s requirement and agreement
 

Steel Grade:
Carbon Steel Grade:
ST35.8, ST37.0, ST44, ST52;
E155, E195, E215, E235, E275, E355;
195GH, P235GH, P265GH, P195TR1, P195TR2, P235TR1, P235TR2, P265TR1, P265TR2;
SAE1010, SAE1020, SAE1026, SAE1035, SAE1045;

Carbon steel tube: SA178, A179, A192, A210, SA213, SA214, etc.
Alloy Steel Grade:
T2, T5, T9, T11, T12, T17, T21, T22, T91,T92, 15Mo3,16Mo3, 13CrMo44;
SAE4130, SAE4140, 40Cr, 40Cr4, 10CrMo910, 12CrMo910, 11CrMo910,
25CrMo4, 35CrMo, 35CrMo4, 42CrMo4, 34CrMo4, 20MnV, 20MnV6,20CrMn;
Carbon steel tube: A179,A192,A210,DIN17175,etc.

Bearing Steel Grades:
GCr15 52100 suj2 suj3 100Cr6 SKF3S SKF3S 20CrNiMo 8620H 4118H;

Nickel Alloy Grade:
N02200/2201, N04400, N06600, N06601, N06625, N06852, N06219, N06690, N08800/8810/8811, N08825, N08028, N08535, N08904, N08925, N08926, N010276, N06022, etc.

Austenitic/Super Austenitic Stainless Steel Grade:
304/304L, 316/316L, 314, 321, 347H, 316Ti, 316LMod, 317L/N, 310S, 253MA, 330, 904L, S31254, XM-19, etc. 

Ferrite/Martensite Stainless Steel Grade:
TP410, TP405, TP420, TP430, TP430Ti, TP403, TP409, TP444, TP439, TP446, etc. 

Duplex/Super Duplex Stainless Steel Grade:
S31803, S32304, S31500, S32550, S32750, S32760, etc. 
Corporate Culture:
We focus on Quality First, Quality Traceability, and Quality Stability!
We focus on Customer First, People First, and Quality-Oriented!
Success:
First factory started in 1997, in the name of Torich , now covers 50000 square meters of factory building, with more than 100employees, and over 45 million RBM assets.
In 2008, we started the company of Torich International Limited for international business and marketing.
Welcome partners from all over the world for long term cooperation!