4130 Chromoly
Tubing & Pipe Supplier
Gnee supply precision 4130 chromoly steel tubing compliant with ASTM A519 and other standards. We offer custom heat treatment, 100% NDT inspection with 3.1 MTC certificates, flexible low-MOQ orders, and fast global delivery at direct factory pricing.
Supplied in all conditions — Annealed, Normalized, Stress Relieved, or Quenched & Tempered.
What Is 4130 Chromoly Tubing?
4130 Chromoly Pipe For Sale
Gnee 4130 chromoly tubing combines superior fatigue resistance with easy weldability. Our 4130 steel tubing supports custom heat treatments for precise mechanical performance. We provide cost-effective, high-performance chrome moly 4130 tube solution for global customers. Bulk Supply From Factory. Request Quote Now.
International Designations — Same Material
| Standard System | Désignation |
|---|---|
| SAE / AISI | 4130 |
| UNS | G41300 |
| AMS (Aerospace) | AMS 6360, AMS 6345 |
| Military | Mil-T-6736B |
| ASTM (Mechanical Tubing) | ASTM A519 Grade 4130 |
| European EN | 25CrMo4 / 1.7218 |
| Japanese JIS | SCM430 |
| British BS | 708A25 |
Available Sizes & Standards
Full size range across two manufacturing methods, covered by all major international standards
Cold Drawn Seamless (CDS)
Tube is drawn through a die at room temperature. Tighter dimensional tolerances, smoother surface finish, and higher strength than hot-finished tube.
Hot Finished Seamless (HFS)
Made by piercing and rolling a heated billet. Slightly looser tolerances and rougher surface than CDS, but available in larger sizes and at lower cost.
Applicable Standards
| Standard | Application |
|---|---|
| ASTMA519 | Seamless carbon and alloy steel mechanical tubing — most common commercial spec |
| AMS 6360 | Aerospace — cold drawn seamless 4130 tubing with tighter controls |
| AMS 6345 | Aerospace — 4130 bars, forgings and tubing |
| Mil-T-6736B | Military specification for 4130 tubing |
| ASME SA519 | Pressure equipment applications (same as ASTM A519) |
4130 Steel Chemical Composition
ASTM A519 4130 — every element serves a purpose
Chemical Composition (wt%)
| Élément | Contenu (%) |
|---|---|
| Carbone (C) | 0.28 – 0.33 |
| Chrome (Cr) | 0.80 – 1.10 |
| Molybdène (Mo) | 0.15 – 0.25 |
| Manganèse (Mn) | 0.40 – 0.60 |
| Silicium (Si) | 0.15 – 0.35 |
| Phosphore (P) | Max 0.035 |
| Soufre (S) | Max 0,040 |
| Fer (Fe) | Balance |
Carbon (0.28–0.33%)
Controls base hardness and strength. Medium-low carbon level means it’s strong but still easy to weld — a critical balance for tubular structures.
Chromium (0.80–1.10%)
Increases hardenability — how deep the steel can be hardened by heat treatment. Also improves corrosion resistance and high-temperature strength.
Molybdenum (0.15–0.25%)
Improves toughness and impact resistance. Increases the steel’s ability to maintain strength at elevated temperatures — critical for aerospace and motorsport.
Manganese (0.40–0.60%)
Improves hardenability and acts as a deoxidizer during steelmaking, contributing to a cleaner microstructure.
Mechanical Properties by Condition
Properties vary depending on the delivery condition — how the tube was treated after manufacturing
Typical Mechanical Properties
| Condition | Résistance à la traction | Limite d'élasticité | Élongation | Dureté |
|---|---|---|---|---|
| recuit | 560 MPa (81 ksi) | 415 MPa (67 ksi) | 28% | ~156 HB |
| Normalisé | 670 MPa (97 ksi) | 485 MPa (63 ksi) | 20% | ~197 HB |
| Normalized & Tempered | 690 MPa (100 ksi) | 550 MPa (80 ksi) | 22% | ~201 HB |
| Quenched & Tempered | 1,020 MPa (148 ksi) | 895 MPa (130 ksi) | 15% | ~302 HB |
Annealed (A)
Slowly cooled after heating. Softest, most ductile condition — easiest to machine and form, but lowest strength.
Normalized (N)
Heated and air-cooled. More uniform grain structure and moderate strength improvement. Most common for general-purpose supply.
Stress Relieved (SR)
Heated to lower temperature to reduce residual stresses. Used when dimensional stability during machining is critical.
Quenched & Tempered (QT)
Oil-quenched from high temperature, then tempered. Highest strength and hardness — for maximum mechanical performance.
Five Performance Advantages
What makes 4130 chromoly steel tubing one of the most versatile alloys in engineering
Strength-to-Weight Ratio
Significantly higher yield and tensile strength than mild steel at the same or lighter wall thickness. Thinner walls, same safety — that’s why aerospace and motorsport engineers have relied on chromoly for decades.
Excellente soudabilité
Easily welded using all commercial processes — TIG (GTAW), MIG (GMAW), and oxy-acetylene. Recommended filler: ER80S-D2 for full-strength welds. Preheating only required for wall thicknesses above 6mm.
Résistance à la corrosion
Chromium content forms a partial passive layer that slows surface oxidation. Significantly better than plain carbon steel. Better suited than stainless for saltwater applications in aviation, racing, and cycling.
Heat Treatable to High Strength
One of few structural alloys that can be heat treated to very high strength while remaining machinable and weldable in annealed condition. Machine first, harden second — a key workflow advantage.
Fatigue & Impact Resistance
Chromium-molybdenum content delivers strong toughness, high fatigue strength, and good impact resistance even at low temperatures. Critical for aircraft structures that flex during flight, roll cages absorbing crash energy, and suspension components handling millions of load cycles.
4130 vs Other Steel Grades
How 4130 chromoly compares to common alternatives — so you choose the right material
4130 vs 1020 Carbon Steel
+76% Strength| Propriété | 1020 Carbon Steel | 4130 Chromoly |
|---|---|---|
| Tensile (norm.) | ~380 MPa | ~670 MPa |
| Yield (norm.) | ~210 MPa | ~435 MPa |
| Hardenability | Low — surface only | Good — through |
| Soudabilité | Excellent | Excellent |
| Corrosion | Poor | Modéré |
| Relative Cost | Lowest | Higher |
| Best Use | General structural | Aerospace, motorsport |
Rule: If you need high strength, heat treatability, or better corrosion resistance — choose 4130. For general low-stress structural, 1020 is more cost-effective.
4130 vs 4140 Chromoly
Same Family| Propriété | 4130 | 4140 |
|---|---|---|
| teneur en carbone | 0.28–0.33% | 0.38–0.43% |
| Strength (QT) | Slightly lower | Higher |
| Soudabilité | Better — easier | Difficult — needs preheat |
| Utilisation typique | Thin-wall tubing, welded structures | Heavy sections, shafts, gears |
Rule: Use 4130 for welded tubular structures (frames, roll cages). Use 4140 for solid bar, shafts, and components that won’t be welded.
Where 4130 Chromoly Is Used
From aircraft frames to oil rig components — trusted across industries where performance is non-negotiable
Aircraft fuselage frames, engine mounts, landing gear components, and hydraulic system tubing. AMS 6360 specification covers tighter dimensional and quality controls.
Race car chassis, roll cages, suspension pick-up points, front and rear subframes, and driveline components. High strength-to-weight ratio directly translates to faster lap times.
High-end road bikes, mountain bikes, and touring bikes. “Chromoly frame” is a recognized quality indicator — better ride quality, stronger and lighter than standard carbon steel.
Downhole tool components, pump housings, valve bodies, and structural wellhead members where strength and moderate corrosion resistance are both needed.
Barrel assemblies, receiver housings, and structural firearm components where strength, machinability, and heat treatability are all required.
Heavy machinery frames, hydraulic cylinder bodies, crane booms, and agricultural equipment structural members where the strength advantage justifies the cost.
Processing Services
Complete in-house processing — your material arrives ready to use. All services can be combined to minimize total lead time.
Cut to Length
1–2 days lead timePrecision cold saws and automated band saws. Tolerance: ±1mm standard, ±0.5mm on request. Square-end and angled cuts available.
Bending
2–5 days lead timeMandrel bending (CNC), rotary draw bending, and hot bending for thick-wall sections. Min 1.5D bend radius. Proper tooling prevents stress cracking.
Traitement thermique
2–4 days lead timeAnnealing, normalizing, stress relieving, and quenching & tempering. Full furnace records and time-temperature charts included. PWHT also available.
Precision Machining
3–7 days lead timeOD centreless grinding (±0.01mm), ID honing for hydraulic cylinders, and gun drilling for deep accurate bores through solid or semi-hollow bar.
Threading & End Prep
1–3 days lead timeNPT, BSPT, API threading, and custom threading to drawing. Bevel end prep (30°/37.5° per ASME B16.25), deburring, and chamfering as standard.
Tube Notching
2–4 days lead timeCNC cope cutting for roll cage fabrication. Angles 30°–90°, to customer drawings or CAD models. Tubes arrive ready to tack-weld with zero gap fitting.
Traitement de surface
2–5 days lead timePhosphate & oil, epoxy primer, powder coating, zinc plating, black oxide, and oiled finish. Options for every environment from indoor storage to outdoor exposure.
Straightening
0–1 day lead timePrecision roller straightening to 1mm per 1,000mm (ASTM A519 requirement). Tighter tolerances available with CNC roller and laser measurement.
NDT & Testing
1–2 days lead timeUltrasonic testing, eddy current testing, hardness testing, and full dimensional inspection. SGS, BV, or TÜV third-party inspection available.
Processing Lead Time Summary
| Service de traitement | Lead Time | Key Specification |
|---|---|---|
| Cut to Length | 1–2 days | ±1mm standard; ±0.5mm precision |
| Bending (mandrel / rotary draw) | 2–5 days | Min 1.5D bend radius |
| Traitement thermique | 2–4 days | Full furnace records provided |
| OD Grinding / ID Honing | 3–7 days | OD ±0.01mm; ID to drawing |
| Threading & Bevel End Prep | 1–3 days | NPT / BSPT / API / custom |
| Tube Notching (cope cutting) | 2–4 days | CNC to drawing, 30°–90° |
| Revêtement de surface | 2–5 days | Primer / powder coat / zinc / P&O |
| Straightening | 0–1 days | 1mm per 1,000mm standard |
| Ultrasonic Testing (UT) | 1–2 days | Full-length automated scanning |
Gnee Real Buyer Cases
How global customers source 4130 chromoly tubing from Gnee Steel
Aircraft Modification Company
Needed AMS 6360 tubing for structural engine mount frames on bush planes. US/EU distributors quoted 8–12 week lead times.
Result: Delivered in 4 weeks with full EN 10204 Type 3.1 documentation. Accepted by airworthiness authority without additional requests. Now sources all chromoly tubing through Gnee.
Off-Road Race Buggy Builder
Needed CDS round tube for chassis and roll cages. Previous supplier had variable wall thickness causing alignment issues during assembly.
Result: 800 kg from a single certified mill with consistent tolerances. Chassis assembly time reduced ~20%, zero alignment corrections required. Standing order placed for three race seasons.
Downhole Tool Manufacturer
Needed large-diameter heavy-wall 4130 in QT condition for machined tool body blanks. European mills quoted 14–16 weeks.
Result: First shipment of 2.5 metric tons in 7 weeks — half the European mill lead time. All hardness values within spec. Approved as qualified supplier.
Pourquoi choisir Gnee Steel
18+ years of alloy steel tubing supply to global B2B buyers — factory-direct with in-house processing
Factory-Direct Supply
No middlemen. Direct from certified mills with full material traceability and competitive pricing.
All Conditions In Stock
Annealed, Normalized, Stress Relieved, and QT — ready to ship from our warehouse inventory.
In-House Processing
Cut, bend, heat treat, machine, coat — all completed before shipment. Material arrives ready to use.
Complete Certification
EN 10204 Type 3.1 standard. Type 3.2, AMS, and ISO documentation available. Third-party inspection by SGS, BV, TÜV.
Low MOQ, Flexible Orders
Trial orders welcome for new customers. Small quantities accepted depending on stock and specifications.
Dedicated Account Manager
Personal technical sales support available 24/7, including weekends and holidays. 24-hour quote response guaranteed.
Questions fréquemment posées
Common questions about 4130 chromoly tubing from buyers and engineers
Chromoly is a short form of chromium-molybdenum — the two key alloying elements in 4130 steel. Chromium improves hardenability and corrosion resistance; molybdenum improves toughness and high-temperature strength. Together, they transform ordinary carbon steel into a high-performance alloy that is significantly stronger, tougher, and more durable.
In common usage, “tubing” and “pipe” are sometimes used interchangeably for 4130 products. Technically, “tubing” is defined by outside diameter and wall thickness (ASTM A519 for mechanical applications), while “pipe” is defined by nominal pipe size and schedule (ASTM A335 for pressure piping). For most structural and mechanical applications, 4130 is ordered as tubing under ASTM A519. When ordering, always specify which standard applies.
Yes. 4130 chromoly round tubing is great for sleeving and bending. In the annealed or normalised condition, it bends well without cracking. Cold bending is possible for thin wall sections. For tighter radius bends, mandrel bending is recommended to prevent wall collapse. Avoid bending in the quenched and tempered condition — the higher hardness increases cracking risk.
The most common recommendation is ER80S-D2, which produces welds that closely match the base metal strength. ER70S-2 is also widely used and produces slightly lower-strength welds — acceptable for many applications. For aerospace applications, consult the applicable welding specification (typically AWS D17.1). Preheating to 150–200°C is recommended for wall thicknesses above 6mm and always for quenched and tempered material.
Most standard sizes in stock accept orders from 50–100 kg. For non-standard sizes, specialty wall thicknesses, or AMS-certified aerospace material, minimum quantities are typically 200–500 kg. Contact us to discuss your specific requirement — trial orders are welcome for new customers.
For standard sizes in stock: loading in 5–10 working days. Production orders: 4–6 weeks. Sea freight from Tianjin or Shanghai: 14–18 days to Southeast Asia, 18–25 days to Middle East, 25–35 days to Europe or North America.
How to Order Correctly
Ordering the wrong specification is an expensive mistake. Include all of the following when contacting suppliers.
Required Information Checklist
Example Order Description
4130 Chromoly Tubing,
ASTM A519, cold drawn seamless,
Round, 50.8mm OD × 3.05mm wall
× 6000mm length,
Normalized condition,
500 kg,
Pickled and oiled finish,
EN 10204 Type 3.1 MTR required.
