ASTM A519 4140 honed tube is a cold-drawn or hot-finished seamless mechanical tube of UNS G41400 chromium-molybdenum alloy steel whose internal bore is finished by precision honing to H8/H9 tolerance and Ra 0.2–0.4 μm. It is the ready-to-assemble barrel of a hydraulic cylinder: the steel carries the hoop stress, and the honed bore carries the seal and the piston. For cylinder service the tube is normally quenched and tempered to 28–32 HRC, and three things decide whether a given order performs - the delivery condition, the finished bore tolerance class, and the wall thickness relative to working pressure.
ASTM A519 is a seamless mechanical tubing specification, not a pressure-pipe standard. It defines the parent tube - chemistry, condition, outside diameter and wall - while honing defines the bore that A519 itself does not cover. The two requirements must be written on the purchase order as one specification, and the cylinder design pressure is calculated separately from the tube geometry and condition.
Technical Specifications
| Parameter | Capability |
|---|---|
| Base standard | ASTM A519 / A519M-24a (Grade 4140, UNS G41400) |
| Outside diameter (parent tube) | Up to 325 mm (12¾ in); typical supply 40–260 mm |
| Wall thickness | Per design, typical 5–40 mm; dimensions quoted as OD × wall, not NPS |
| Finished bore (ID) | Custom to drawing; tolerance H7 / H8 / H9 per ISO 286-1 |
| Surface finish (bore) | Ra 0.2–0.4 μm honed; Ra ≤0.2 μm SRB |
| Straightness | ≤0.3 mm/m standard; ≤0.1–0.15 mm/m for long barrels |
| Length | Up to 12 m, fixed or random |
| Ends | Plain, beveled or threaded; bore protected by plastic caps |
| Heat treatment | Annealed / normalized / stress-relieved / quenched & tempered |
| Certification | EN 10204 3.1; third-party inspection (SGS / BV / TÜV) available |
Chemical Composition
The A519 4140 chemical composition is a chromium-molybdenum balance governed by UNS G41400; the limits below are heat-analysis values.
| Element | 4140 (max / range) |
|---|---|
| Carbon (C) | 0.38–0.43 % |
| Manganese (Mn) | 0.75–1.00 % |
| Phosphorus (P) | 0.040 % max |
| Sulfur (S) | 0.040 % max |
| Silicon (Si) | 0.15–0.35 % |
| Chromium (Cr) | 0.80–1.10 % |
| Molybdenum (Mo) | 0.15–0.25 % |
Chromium and molybdenum are what lift 4140 above plain carbon grades: chromium adds strength and hardenability, molybdenum adds toughness and high-temperature stability. Product analysis carries the A519 Table 5 tolerance (+0.005 for P and S), so a mill certificate is read against the heat-analysis limits plus that tolerance.
Mechanical Properties
The A519 4140 mechanical properties depend on delivery condition; the table gives A519 base-table minimums by condition.
| Condition | Yield MPa (ksi) | Tensile MPa (ksi) | Elongation |
|---|---|---|---|
| Annealed (A) | ≥414 (60) | ≥552 (80) | ≥25 % |
| Normalized (N) | ≥621 (90) | ≥855 (120) | ≥20 % |
| Stress-relieved (SR) | ≥689 (100) | ≥855 (120) | ≥10 % |
| Hot-finished (HF) | ≥621 (90) | ≥855 (120) | ≥15 % |
| Quenched & tempered (Q&T) | Not in the A519 base table - specified by the purchaser; cylinder barrels are normally 28–32 HRC (UTS 850–1000+ MPa, yield 700–850+ MPa) | ||
The common mistake is to read "4140" as one fixed strength. A519 fixes chemistry and condition, not a single yield - the annealed condition gives ≈414 MPa yield, while a Q&T barrel gives 700+ MPa. Designing a pressure barrel to the annealed value leaves roughly a third of the available strength unused. Elongation is measured on a 50 mm (2 in) gauge length and varies with condition, so it is not a single constant.
Grade and Process Comparison
| Requirement | 4140 (A519) | 42CrMo4 (EN 10305-1) | 4130 |
|---|---|---|---|
| Material number | UNS G41400 | 1.7225 | G41300 |
| Typical Q&T yield | 700–850+ MPa | 700–900 MPa (≤16 mm) | Lower; often used annealed/SR |
| Typical use | Heavy hydraulic barrels | European-spec barrels | Lighter, lower-load barrels |
In the honed tube vs SRB tube choice, both finish the bore to a precision tolerance. Honing removes material with stones and gives Ra 0.2–0.4 μm; SRB skives and roller-burnishes, work-hardens the surface and reaches Ra ≤0.2 μm. The decision is driven by seal type, volume and cost, not by a simple "better."
Selecting the Right Grade and Delivery Condition
The A519 4140 delivery condition, not the grade name, decides the design value. For hydraulic cylinder barrels, quenched and tempered 4140 tube at 28–32 HRC is the default: it delivers the controlled strength and fatigue resistance a pressure barrel needs. Annealed 4140 (≈414 MPa yield) is too soft for pressure service and is a machining blank, not a barrel. Cold-drawn-hard (+C) carries residual stress that can distort the bore during honing, so it is avoided for barrels.
| Condition | Hardness | Use for the barrel? |
|---|---|---|
| Q&T (+QT) | 28–32 HRC | Yes - standard for pressure barrels |
| Normalized (+N) | ~190–240 HB | Weldable blanks, non-pressure |
| Stress-relieved (+SR) | ~190–230 HB | Stable bore, light duty |
| Annealed (+A) | ≤197 HB | Machining stock, not a barrel |
On the bore side, the 4140 honed tube id tolerance H8 H9 and the 4140 honed tube surface finish Ra 0.2 to 0.4 μm are selected by seal type and pressure, while the A519 4140 dimensions OD wall are stated as outside diameter × wall, never as NPS or schedule.
When the project is documented to European standards, specify 42CrMo4 honed tube (1.7225) to EN 10305-1 (or EN 10297-1 for heavy walls); the steel is the same as 4140 and the certificate simply follows the EN format. The A519 parent tube and the honed bore are independent decisions, so state both.
Applications
The ASTM A519 4140 hydraulic cylinder tube is specified wherever a finished, ready-to-assemble cylinder barrel must carry high pressure, shock loads and millions of cycles without secondary boring. A 4140 honed tube for hydraulic cylinder service is the standard feedstock for heavy-duty cylinders, and five application groups cover most orders:
Hydraulic cylinder barrels
The dominant use. Excavator boom and arm cylinders, crane and loader cylinders, and agricultural loader arms run at 160–350 bar with impact loading, and the honed 4140 Q&T bore is the part that actually seals and guides the piston.
Injection molding and press cylinders
Clamping and injection rams cycle millions of times per year; 4140's fatigue resistance and a stable, honed bore keep leakage and downtime low.
Mining and off-highway equipment
Dump-truck hoist cylinders and drill rig rams see shock loads and abrasive sites. Heavy-wall 4140 Q&T barrels resist yielding and bore scoring.
Industrial and mobile hydraulic actuators
Steering cylinders, hatch covers, deck machinery and robotic arms use the same tube where a precise, clean bore shortens assembly time.
Aerospace and oilfield actuators
Aircraft landing-gear hydraulics and wellhead control actuators use 4140 (and 4130) where strength-to-weight and traceable chemistry matter.
Selecting the Right Grade and Delivery Condition
The A519 4140 delivery condition, not the grade name, decides the design value. For hydraulic cylinder barrels, quenched and tempered 4140 tube at 28–32 HRC is the default: it delivers the controlled strength and fatigue resistance a pressure barrel needs. Annealed 4140 (≈414 MPa yield) is too soft for pressure service and is a machining blank, not a barrel. Cold-drawn-hard (+C) carries residual stress that can distort the bore during honing, so it is avoided for barrels.
| Condition | Hardness | Use for the barrel? |
|---|---|---|
| Q&T (+QT) | 28–32 HRC | Yes - standard for pressure barrels |
| Normalized (+N) | ~190–240 HB | Weldable blanks, non-pressure |
| Stress-relieved (+SR) | ~190–230 HB | Stable bore, light duty |
| Annealed (+A) | ≤197 HB | Machining stock, not a barrel |
On the bore side, the 4140 honed tube id tolerance H8 H9 and the 4140 honed tube surface finish Ra 0.2 to 0.4 μm are selected by seal type and pressure, while the A519 4140 dimensions OD wall are stated as outside diameter × wall, never as NPS or schedule.
When the project is documented to European standards, specify 42CrMo4 honed tube (1.7225) to EN 10305-1 (or EN 10297-1 for heavy walls); the steel is the same as 4140 and the certificate simply follows the EN format. The A519 parent tube and the honed bore are independent decisions, so state both.
Quality Control and Testing
Chemistry and certificate. Heat analysis to A519 limits, reported on an EN 10204 3.1 mill test certificate with heat and condition.
Mechanical verification. Tension, hardness and (for Q&T) hardness confirmation per ASTM A370; elongation on the specified gauge length.
Bore verification. ID gauging to H7/H8/H9, roughness measured (Ra/Rz), and straightness checked over the length.
NDT of the parent tube. UT or eddy-current where specified, performed before honing.
Third-party inspection. SGS, BV or TÜV nominated by the buyer on request; cleanliness to NAS 8–10 where the cylinder assembly demands it.
Why Source ASTM A519 4140 Honed Tube from GNEE
Supply both the A519 parent tube and the precision honing in one order, with condition and bore tolerance stated on the same certificate.
Stock and conversion across OD 40–260 mm, ID and H7/H8/H9 tolerance, Ra 0.2–0.4 μm honed or Ra ≤0.2 μm SRB.
EN 10204 3.1 certificates, SGS/BV/TÜV third-party inspection, and heat-number traceability on every lot.
Technical quotation within 24 hours, with bore-critical cut-to-length, NAS cleaning and export seaworthy packaging.
Test and inspection
Packaging and shipping
Send your finished bore ID × OD (or minimum wall) × length, grade, delivery condition (Q&T 28–32 HRC), H tolerance and Ra, and our technical team will confirm the specification and return a quotation with lead time within 24 hours.
Request an ASTM A519 4140 Honed Tube Quote
FAQ
What is an ASTM A519 4140 honed tube?
An ASTM A519 4140 honed tube is a cold-drawn or hot-finished seamless mechanical tube made from UNS G41400 chromium-molybdenum alloy steel, with its internal diameter finished by precision honing to H8/H9 tolerance and Ra 0.2–0.4 μm. ASTM A519 defines the parent tube; honing defines the bore, so the two requirements must be specified separately on the purchase order.
Is ASTM A519 4140 rated for pressure service?
No. ASTM A519 is a mechanical tubing specification and carries no pressure rating. Hydraulic-cylinder design pressure must be calculated separately from the tube geometry, delivery condition, end construction and applicable design rules. For pressure-service pipe, specify ASTM A106 or A335 instead.
What delivery condition should 4140 honed tube be supplied in for hydraulic cylinders?
For hydraulic cylinder barrels, 4140 is normally supplied quenched and tempered (Q&T) at 28–32 HRC, with hardness confirmed on the mill test certificate. Annealed 4140 (≈414 MPa yield) is too soft for pressure barrels: in one reported field case a buyer specified only '4140 tube', received annealed stock, and the barrels permanently deformed under a 280 bar hydrotest because the design assumed 650+ MPa yield.
What ID tolerance and surface finish does a 4140 honed cylinder tube have?
Finished bore tolerance is typically H8 or H9 per ISO 286-1 (H7 for servo or leakage-critical cylinders), and honed surface roughness is Ra 0.2–0.4 μm with a 30–45° cross-hatch. Skived and roller burnished (SRB) tubes reach Ra ≤0.2 μm. Straightness is normally ≤0.3 mm/m, with ≤0.1–0.15 mm/m available for long, slender barrels.
Does ASTM A519 4140 require hydrostatic testing?
Not by default. Because A519 tubing is not rated for pressure service, hydrostatic testing is an optional supplementary requirement (S1) that must be stated on the purchase order. Ultrasonic or eddy-current examination is also specified only when requested.
What is A519 4140 equivalent to in the European system?
A519 4140 is the U.S. grade; its European equivalent is 42CrMo4 under material number 1.7225 (EN 10083-3 / EN 10305-1), with Japanese SCM440 and Chinese 42CrMo as further equivalents. The steels are nearly identical; the choice is usually driven by the project's documentation and certification standard.
Is ASTM A519 the same as ASTM A106?
No. ASTM A519 is seamless mechanical tubing for machining and structural use, with no pressure rating and no mandatory hydrotest. ASTM A106 is seamless pipe for high-temperature pressure service, pressure-rated with different chemistry limits and a mandatory hydrostatic test. They are not interchangeable.
Can A519 4140 honed tube be welded?
Yes, but 4140 has a high carbon equivalent - CE_IIW ≈ 0.79 and CE_Pcm ≈ 0.52 for a typical heat - so welds need preheat of 150–260°C and controlled cooling to avoid cold cracking. Q&T condition demands even more care; the carbon equivalent is not printed on the certificate and must be requested separately.