Alloy Steel 4130 - widely used in the Aerospace, Defence & Motorsport industry

Alloy Steel 4130

4130 – AMS-T-6736 | AMS6371 | AMS6360 | AMS6361 | AMS6362

Product description

With superior strength and good workability, this Chromium Molybdenum based alloy has a rich history in usage across Aerospace and Motorsport industries. This High Strength Steel (HSS) has many acronyms, but is more commonly referred to 4130, its Society of Automotive Engineers (SAE) designation or Chromoly, which is a more palatable version of Chromium Molybdenum.

The 4130 standard falls under the SAE (Society of Automotive Engineering) and AISI (American Iron & Steel Institute) four digit numbering system where;

  • 4
    4
    Designates the material type as a Molybdenum steel
  • 1
    1
    1
    Designates the material further as a Chromium-Molybdenum steel
  • 30
    4130
    30
    Designates the material as Chromium-Molybdenum steel with an average Carbon content 0.30%, hence the final designation as 30.
4 Designates the material type as a Molybdenum steel
1 Designates the material further as a Chromium-Molybdenum steel
30 Designates the material as Chromium-Molybdenum steel with an average Carbon content 0.30%, hence the final designation as 30.

The 4130 designation gives guidance to the base grade, but in conjunction with further specifications, we have a product with chemical and mechanical limits, along with manufacturing guidelines and thermal treatments. 4130 manufactured in conjunction with these further specifications, builds a product which should be consistent in mechanical properties.

Due to the strength to weight ratio of this steel, it was widely used in the aerospace industry, and was adopted under the SAE’s Aerospace Material Specification committee. Subsequently, an AMS standard was published to give guidance on manufacturing processes, thermal treatments, chemistry, and mechanical requirements.

Technical Specification

Specification Material Publication Date
AMS6360 Steel Tubing, Seamless 01/12/1939
AMS6361 Steel Tubing, Seamless 01/06/1942
AMS6362 Steel Tubing, Seamless 01/06/1942
AMS6371 Steel Mechanical Tubing 01/12/1942
MIL-T-6736 Tubing, Chrome-Molybdenum 01/06/1950
AMS-T-6736 Tubing, Chrome-Molybdenum 01/12/1990
AMS6348 Steel, Bars 01/10/1979
AMS-S-6758 Steel, Chrome-Molybdenum Bars and Reforging Stock 01/07/1998
AMS6370 Steel, Bars, Forgings and Rings 01/12/1939
AMS6350 Steel, Sheet, Strip and Plate 01/12/1942
AMS6345 Steel, Sheet, Strip and Plate 01/11/1996

In an attempt to try and unify the designations used, a system called the Unified Numbering System was developed by the American Society for Testing and Materials (ASTM) and Society of Automotive Engineers (SAE) in 1972.

Technical Data

Mechanicals Chemistry
SpecificationTensile StrengthYield StrengthElongation
AMS636095 ksi minimum75 ksi minimum12% minimum
AMS6361125 ksi minimum100 ksi minimum12% minimum
AMS6362150 ksi minimum135 ksi minimum10% minimum
AMS634595 ksi minimum75 ksi minimum10% minimum

So what’s the deal with the weight of 4130 vs. standard steels? Truth is, nothing at a non-micro scale. Refer to our description section for the origins of the chromoly and 4130 name, but essentially it’s an alloy steel categorized in the Molybdenum Chromium family. What’s this got to do with weight? Well ultimately, the family this steel lives in sounds fun, but it's still 96.7% minimum iron, and therefore, iron has the greatest impact when looking at the weight. The table below shows the chemical differences between 4130 and a ERW (Electric Resistance Welded) tube.

4130 Chromoly per AMS6360
ElementLower %Upper %
Carbon0.280%0.330%
Manganese0.400%0.600%
Silicon0.150%0.350%
Phosphorus-0.025%
Sulfur-0.025%
Chromium0.800%1.100%
Molybdenum0.150%0.250%
Nickel-0.250%
Copper-0.350%
IronBalanceBalance
Typical ERW per E220
ElementAverage %
Carbon0.140%
Manganese0.700%
Silicon0.350%
Phosphorus0.025%
Sulfur0.025%
IronBalance

Based on the above examples, we see 4130 with a minimum iron percentage of 96.7%, and ERW with an average iron percentage of 98.7%. It would be fair to say that iron is the common denominator, and the balance elements are in real terms, a very small percentage, so the overall density of the material in hand would be very similar. So unless you have some super tolerance scales, you will not see the difference in like for like material sizes. Strength, consistency of product, and manufacturing processes however are a different thing all together.

Aerocom Stock List

Tube Sheet & Plate Bar
WT Inches
OD (Inches)0.0280.0350.0490.0580.0650.0830.0950.1250.156
0.148x
0.250xxx
0.313xxxx
0.375xxxxxxx
0.438xxx
0.500xxxxxxxxx
0.625xxxxxxxx
0.750xxxxxxxxx
0.875xxxxxxx
1.000xxxxxxxxx
1.125xxxxxxx
1.250xxxxxxxx
1.375xxxxxxx
1.500xxxxxxxx
1.625xxxxxxxx
1.750xxxxxxx
1.875x
2.000xxxxxx
2.125x
2.500xxx
Specification
Thickness (Inches)AMS6345AMS6350
0.025xx
0.032xx
0.036x
0.040xx
0.050xx
0.063xx
0.071xx
0.080xx
0.090xx
0.100xx
0.125xx
0.160xx
0.190xx
0.250xx
0.375x
0.500xx
0.625
0.750xx
0.875x
1.000xx
1.250xx
1.500xx
1.750xx
2.000xx
3.000xx
Stock
Diameter (Inches)
0.125x
0.250x
0.313x
0.375x
0.438x
0.500x
0.625x
0.750x
0.813x
0.875x
1.000x
1.250x
1.250x
1.375x
1.500x
1.625x
1.750x
2.000x
2.250x
2.500x
3.000x
4.000x
5.000x

Our Approvals

Leonardo Aerostructures Leonardo Aircraft Leonardo Helicopters Airbus Helicopters
UTC SAFRAN GE Power ISO9001:2015
AS9120B Westland SQA50 Britten-Norman

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