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AISI 4140 Steel Specifications

ASTM A29 | Chromium-Molybdenum Low Alloy Steel

Complete specifications for AISI 4140 low alloy steel, the most widely used chromium-molybdenum steel for oil patch applications and high-strength manufacturing components.

AISI 4140 Steel Overview

Material Description

AISI 4140 low alloy steel containing chromium and molybdenum is the most widely used low alloy steel for oil patch applications. Usually supplied in the hardened and tempered condition at 22 HRC maximum, it also finds favor in applications requiring higher strength levels up to 150 KSI.

The hardenability limitations of this grade must always be taken into account when designing equipment. Several hybrid analyses are available, with the most common modification increasing molybdenum to 0.35% max to improve hardenability.

Key Benefits:

  • Excellent hardenability and strength
  • Good toughness and wear resistance
  • Versatile heat treatment response
  • Widely available and cost-effective

Available Forms

Round Bars

1" to 12" diameter

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Seamless Tubes

Downhole tool applications

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Flat Bars

Various dimensions

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Forgings

Custom shapes available

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Technical Specifications

Chemical Composition (%)

ElementMin %Max %
C0.380.43
Si0.150.35
Mn0.751.00
P-0.035
S-0.040
Cr0.801.10
Mo0.150.25
FeBalanceBalance

Mechanical Properties

Hardened and Tempered (22 HRC Max)
Ultimate Tensile Strength:100 ksi min (689 MPa)
0.2% Yield Strength:80 ksi min (552 MPa)
Elongation in 2 inches:20% min
Reduction of Area:40% min
Hardness (Rockwell C):22 HRC max
Higher Strength Heat Treatment
Ultimate Tensile Strength:130 ksi min (896 MPa)
0.2% Yield Strength:110 ksi min (758 MPa)
Elongation in 2 inches:18% min
Reduction of Area:30% min
Hardness (Rockwell C):28-32 HRC

AISI 4140 Applications by Industry

Oil & Gas

Common Applications:

  • Downhole tools
  • Drill collars
  • Stabilizers
  • Pump rods
  • Casing accessories
  • Wellhead components

Key Benefits:

Excellent hardenability and strength for demanding downhole applications

Service Temperature:Up to 400°F (204°C)

Industrial Manufacturing

Common Applications:

  • Shafts and axles
  • Gears and sprockets
  • Bolts and fasteners
  • Machine components
  • Hydraulic cylinders
  • Tool holders

Key Benefits:

High strength-to-weight ratio with good toughness and wear resistance

Service Temperature:Up to 400°F (204°C) continuous

Technical Resources & Downloads

AISI 4140 Technical Datasheet

Complete chemical composition, mechanical properties, and heat treatment specifications

Heat Treatment Guide

Detailed procedures for achieving various strength levels and hardness ranges

Hardenability Chart

Jominy hardenability curves and depth penetration data for 4140 steel

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