Low Alloy Steels

AISI 4140

Low alloy 4140: ASTM A29 (VO1.05)

General scope

AISI 4140 low alloy steel containing Chromium and Molybdenum is the most widely used alloy for oil patch applications. Usually supplied in the hardened and tempered condition at 22 HRC max. it also finds favour in many applications requiring higher strength levels up to 150 KSI 0.2% PS. The grade is not NACE MR0175 approved in these conditions, and should not be used in environments containing H2S.

It is extensively used in tubular form for downhole tools.

Several hybrid analysis are available all based on the AISI chemistry. The most common change is to increase the Molybdenum level at 35% max on diameters, typically greater than 6". Increasing Molybdenum improves the hardenability.

The hardenability limitations of this grade (depth to which it will harden / obtain the specified mechanical properties after heat treatment) must always be taken into account when designing and selecting equipment.

Chemical composition

Various hybrid analyses are available to improve the hardenability of the grade.
C Si Mn P S Cr Mo Fe
Min 0.38 0.15 0.75 0.80 0.15 0.00
Max 0.43 0.35 1.00 0.035 0.040 1.10 0.25 0.00

Mechanical properties

Condition: Hardened and Tempered to 22 HRC max

U.T.S 100 KSI Min (689 N/mm2)
0.2% Proof Stress 80 KSI Min (551 N/mm2)
Elongation 20 %
Red of Area 40 %

Condition: Hardened and Tempered to 30-36 HRC max

NACE MR0175 limits the supply hardness to 22HRC max.
U.T.S 130 KSI Min (896 N/mm2)
0.2% Proof Stress 110 KSI Min (758 N/mm2)
Elongation 13 %
Red of Area 30 %
Size range: 1”∅ - 28”∅

Primarily manufactured in:

  • Dubai, UAE
  • Edmonton, Canada
  • Houston, Texas
  • Sheffield, England
  • Singapore
More in Low Alloy Steels
« AISI 4145 AISI 4130 »