AISI 4130
CHROMOLY STEEL (Cr-Mo)
Lighter. Stronger. The ultimate alloy for high-stress fabrication. We supply normalized 4130 tubing and sheets with a superior strength-to-weight ratio.
Decoding the Alloy
The name "4130" is not random. It is a precise engineering recipe defined by the AISI/SAE naming system, balancing strength and weldability.
The Strength Advantage
Why choose 4130 over standard carbon steel? The answer lies in the Yield Strength—allowing engineers to use thinner walls to save weight without sacrificing safety.
Because 4130 is nearly 2x stronger than mild steel, you can use thinner wall tubing to support the same load. This typically results in a 25-30% weight reduction for the final chassis structure.
Engineered for Extremes
From the race track to the sky, 4130 Chromoly is the material of choice where failure is not an option.
Motorsports & Racing
The universal standard for roll cages, chassis fabrication, and suspension components in Drag Racing (NHRA), Rally, and Baja.
General Aviation
Used extensively in fuselage tubing for small aircraft, engine mounts, and landing gear struts.
Performance Cycling
Favored for high-end BMX, Gravel, and Touring bike frames where ride quality and durability are paramount.
Oil & Gas Industry
Critical for high-pressure valves, fittings, and drilling tools that must survive harsh environments.
Stock Availability
We stock a comprehensive range of AMS-certified 4130 in our climate-controlled warehouse.
Seamless Tubing
AMS 6360 / 6371Sheet & Plate
AMS 6350 / 6345Round Bar
AMS 6348Fabrication FAQ
Expert answers to common questions regarding welding, heat treatment, and finishing of 4130 alloy.
Do I need to heat treat 4130 after welding?
Rule of Thumb: Thickness Matters.
For thin-wall tubing (typically under 0.120" or 3mm) common in motorsports and cycling, post-weld heat treatment (stress relief) is usually not required if proper TIG procedures are followed. However, for thicker plates or multi-pass welds, stress relief is highly recommended to prevent Heat-Affected Zone (HAZ) cracking.
Can I MIG weld 4130 Chromoly?
Yes, but TIG (GTAW) is the industry standard for aerospace and racing due to its superior control and lack of spatter. If you must MIG weld, use ER80S-D2 filler wire. Crucially, avoid rapid cooling (quenching) as this will make the weld brittle. Pre-heating to 300°F-400°F is recommended for thicker sections.
Does 4130 steel rust?
Yes. 4130 is a low-alloy carbon steel, not stainless steel. It contains ~97% iron and will oxidize (rust) quickly if exposed to moisture. All finished parts must be protected via painting, powder-coating, or plating (e.g., Nickel or Zinc) to ensure longevity.
Is 4130 harder to machine than mild steel?
Yes, it is tougher and harder than standard 1018/1020 steel. It generates more heat during cutting. We recommend using carbide tooling, running at slightly slower speeds (approx. 60-70% of mild steel speeds), and using adequate coolant. However, it machines cleanly and produces a excellent surface finish.