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We are a world-class supplier of engineering raw materials. Our objective is to provide all our customers, from the small machine shop to the large multi-national corporation, a supply path that continuously delivers the highest levels of service, quality and value.

4130 (AMS 6346, SAE 4130)

Chromium Molybdenum Alloy Steel

4130 Steel Alloy

This chromium-molybdenum alloy is one of the most widely used aircraft steels because of its combination of weldability, ease of fabrication and mild hardenability.


In relatively thin sections it will respond to heat treatment to high strength levels and yet in the normalised condition it has adequate strength for many applications. When resistance to wear and abrasion is required, it may be nitrided. This grade is a quality product melted under the best steelmaking practices for aircraft quality steels. It is vacuum degassed to meet the magnetic particle inspection standards of AMS 2301. The density of this material is typically 7.85kg/dm³.


Intended for use in the manufacture of parts and components with sections ½” thick or less at time of heat treatments which required a through-hardening steel capable of developing hardness as high as Rockwell “C” 35, and also for parts with greater thickness requiring proportionately lower hardness. It may be used for parts requiring fusion welding. Hardenability and weldability are considered equivalent to 8630 (MIL-S-6250).

Typical Applications

Commercial applications for this engineering material include:

  • Fusion welded parts
  • Parts requiring lower hardness
  • Aircraft components

We stock AMS 6346 (4130) in flats, round bar, plate, sheet, round tube, rectangular tube, square tube, hollow bar, square bar and hexagon bar.

Technical Assistance

Our knowledgeable staff and resident metallurgists will be pleased to assist you further on any technical topic. Smiths Metal Centres Limited also boasts an in-house UKAS Accredited Testing Laboratory which is unique within the multi-metal and plastic stockholding sector. We believe this underlines our total commitment to quality and our ethos of being the complete service provider.

Additional Info

A technical datasheet for AMS 6346 (4130) is available in PDF file format. To view and download, please click here.

We offer in-house processing options - for more information, please refer to our processing services.

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