4130 Chromoly Tubing
4130 chromoly tubing is seamless tube made from a chromium-molybdenum low alloy steel. It combines high strength with good weldability, which is why it is the standard choice for roll cages, race chassis, light aircraft structures and highly loaded machine parts.
What Makes 4130 Distinct
Compared with standard carbon steel, the alloying additions in 4130 — chromium (approximately 0.80–1.10%) and molybdenum (approximately 0.15–0.25%) — increase hardenability, improve toughness, and allow the steel to achieve higher yield strength in heat-treated conditions. The carbon content is low enough to retain reasonable weldability, making it practical for fabricated structures.
Note: Specific chemistry limits depend on the applicable specification. Buyers should refer to the ladle analysis on the Mill Test Certificate for the actual values of the specific heat supplied.
| Designation | Description |
|---|---|
| AISI / SAE 4130 | North American alloy identification — chromium-molybdenum family |
| UNS G41300 | Unified Numbering System designation |
| 25CrMo4 | European EN equivalent |
| 1.7218 | European material number (Werkstoff-Nr) |
| Supply form | Seamless tubing |
| OD range (verified) | 0.25 in – 5.0 in |
| Wall range (verified) | 0.035 in – 0.500 in |
| Certification | EN 10204 3.1 MTC available |
Manufacturing Form
The standard supply form for structural and aerospace-grade 4130 is Cold Drawn Seamless (CDS). The seamless manufacturing process — piercing a solid billet rather than welding a formed strip — results in a tube with no longitudinal weld seam. This is important for applications where isotropic strength across the full cross-section is required, or where the applicable standard mandates seamless manufacture.
Applicable Standards
4130 seamless tubing is commonly supplied to ASTM A519 (Seamless Carbon and Alloy Steel Mechanical Tubing). For aerospace applications, AMS-T-6736 (formerly MIL-T-6736) governs. The EN equivalent for seamless mechanical tubes is EN 10297. Buyers should specify the applicable standard at the enquiry stage, as the dimensional and testing requirements vary between specifications.
Ordering Requirements
A complete purchase specification for 4130 chromoly tubing should include: Outside Diameter (OD) in decimal inches or millimetres, wall thickness, total footage or weight, manufacturing form (Cold Drawn Seamless), applicable standard or condition (e.g., Normalized), and documentation requirement (EN 10204 3.1 MTC). Incomplete specifications result in re-quoting delays or incorrect material being supplied.
Composition and Where to Go Next
| Element | AISI 4130 range (%) |
|---|---|
| Carbon | 0.28 – 0.33 |
| Manganese | 0.40 – 0.60 |
| Chromium | 0.80 – 1.10 |
| Molybdenum | 0.15 – 0.25 |
| Silicon | 0.15 – 0.35 |
| Phosphorus, sulphur | 0.040 maximum each (typical standard limit) |
The heat analysis of the tube you receive is recorded on its mill test certificate. For the role of each element see chemical composition; for strength figures see mechanical properties.
From here, the quickest routes are the size chart for dimensions, seamless tubing for how the product is made, ASTM A519 for the governing standard and normalized tubing for the usual delivery condition. Every page is listed in the product and guide index.
Frequently Asked Questions
What does '4130' mean in the grade designation?
The first two digits (41) identify the alloy family — chromium-molybdenum. The last two digits (30) indicate the nominal carbon content in hundredths of a percent, so 0.30% nominal carbon.
Is 4130 the same as chromoly?
'Chromoly' is an informal term for chromium-molybdenum alloy steel. 4130 is the most widely used chromoly tubing grade. Not all chromoly steel is 4130 — 4140 and 4340 are also chromoly grades — but in the context of tubing, '4130 chromoly' refers specifically to this grade.
Can 4130 tubing be welded?
Yes. 4130 has adequate weldability for TIG (GTAW) welding using appropriate filler metal and technique. Thicker walls or high-constraint joints may require pre-heating and post-weld heat treatment. The applicable welding procedure specification should be consulted for the specific application.
What sizes does 4130 chromoly tubing come in?
Regular supply covers roughly 0.250" to 5.000" outside diameter in walls from 0.035" to 0.500". Confirm the specific combination when you enquire.
Does 4130 chromoly tubing rust?
Yes. It is not a stainless steel and needs oil, primer, paint or another coating to protect it.
Request a Quotation
Provide your complete specification to receive an accurate B2B quotation.
- Outside Diameter (OD) in inches or mm
- Wall Thickness in inches or mm
- Total footage or weight
- Manufacturing form (Cold Drawn Seamless preferred)
- Applicable standard or condition
- EN 10204 3.1 MTC requirement
- Delivery location