27SiMn SRB Honed Tube: An Overview
Oct 08, 2026
27SiMn SRB honed tube is a quenched and tempered 27SiMn (GB/T 17396) seamless mother pipe finished to a skived and roller-burnished bore, ready to receive a piston and seal without further machining. A standard barrel carries an inside diameter of 40-500 mm (1.6-20 in) held to ISO H8 with a surface roughness of Ra 0.2 um, and is designed to the mother-pipe quenched-and-tempered strength of 980 MPa tensile and 835 MPa yield. The single most important check is the delivery condition, because the same 27SiMn name covers both the 980/835 MPa quenched-and-tempered barrel and weaker as-rolled stock that should never be used for a pressure cylinder.
A 27SiMn SRB tube belongs to the family of honed tubes used as hydraulic cylinder barrels, where the finished bore - not the outside diameter - is the product. The skiving and roller burnishing route is the volume-production standard for mobile and industrial cylinders worldwide, so we present it here as a finished cylinder component rather than as a raw steel grade, and we separate the mother-pipe properties from the bore finish that makes the part work.
Technical Specifications
| Parameter | Capability |
|---|---|
| Grade & standard | 27SiMn (GB/T 3077-2018); mother pipe GB/T 17396-2022 |
| Inside diameter (ID) | 40-500 mm (1.6-20 in); up to 630 mm on request |
| Wall thickness | 4-60 mm (varies with ID), imperial sizes on request |
| Length | up to 12 m; cut-to-length 1-9 m typical |
| Bore tolerance | ISO H8 (H9 economy option) |
| Internal surface roughness | Ra 0.2 um (SRB); Ra 0.4 um (honed) |
| Straightness | 0.3 mm/m or better |
| Roundness | within ID tolerance |
| End condition | plain square-cut deburred, or bevelled with plastic cap |
| Surface | bare, oiled, varnished or polished per request |
| Delivery condition | quenched and tempered (QT) |
| Certification | EN 10204 3.1 / 3.2; third-party SGS, BV, TUV, DNV available |
Chemical Composition
| Element | 27SiMn |
|---|---|
| Carbon (C) | 0.24-0.32 % |
| Silicon (Si) | 1.10-1.40 % |
| Manganese (Mn) | 1.10-1.40 % |
| Phosphorus (P) | 0.035 % max |
| Sulfur (S) | 0.035 % max |
| Chromium (Cr) | 0.30 % max |
| Nickel (Ni) | 0.30 % max |
| Copper (Cu) | 0.30 % max |
The 27SiMn chemical composition below is the ladle-analysis requirement of GB/T 17396 and GB/T 3077. The high silicon (1.10-1.40%) and manganese (1.10-1.40%) are deliberate: together they raise the elastic limit and hardenability so the steel reaches high strength after quenching and tempering. The residual chromium, nickel and copper are capped, not specified - they are impurities, not alloying additions, which is why 27SiMn is not a chromium-molybdenum steel.
Mechanical Properties
| Property | 27SiMn (QT) |
|---|---|
| Tensile strength Rm (min) | 980 MPa (142 ksi) |
| Yield strength ReH (min) | 835 MPa (121 ksi) |
| Elongation A (min) | 12 % |
| Reduction of area Z (min) | 40 % |
| Impact AKv2 at 20 C (min) | 39 J |
| Hardness (max) | 217 HBW |
| Test standards | GB/T 228.1, GB/T 229, GB/T 231 |
The 27SiMn mechanical properties above are the mother-pipe quenched-and-tempered values a hydraulic cylinder tube is supplied and designed to. A cold-finished barrel may test slightly higher because of work hardening, but the design basis remains the 980/835 MPa mother-pipe values; do not confuse them with the weaker as-rolled or normalised condition some suppliers quote.
SRB vs Honed vs NBK - Bore Finish Choice
| Finish | Process | Roughness Ra | Bore tolerance | Best for |
|---|---|---|---|---|
| NBK (as-drawn) | cold-drawn only | 1.6-3.2 um | ±0.15-0.25 mm | prototype, in-house finishing |
| SRB | skive + roller burnish | 0.2-0.8 um (0.2 um typical) | ISO H8 | volume mobile/industrial cylinders |
| Honed | abrasive stone crosshatch | 0.2-0.4 um | ISO H8 or tighter | servo, proportional, large bore |
The SRB vs honed tube choice comes down to roughness, surface layer and cost, not to a different grade - a 27SiMn honed tube and a 27SiMn SRB tube share the same quenched-and-tempered mother pipe. SRB and honing are different operations, not one process marketed under two names. SRB removes a thin layer by skiving then plastically deforms the surface with hardened rollers, producing a near-mirror, work-hardened bore with an ID tolerance H8 class quickly and cheaply. Honing uses abrasive stones to cut an intentional 30-60° crosshatch that retains an oil film for servo-grade seals. A smoother Ra is not automatically better: below about Ra 0.1 um the mirror cannot hold a lubricant film, which raises friction and accelerates seal wear. Around 60-70% of production cylinders worldwide use SRB tubes.
27SiMn vs E355 vs 20MnV6 vs 42CrMo4
| Grade | Standard family | Yield (min) | Best use |
|---|---|---|---|
| 27SiMn (QT) | GB/T 17396 (China) | 835 MPa | heavy-duty, high-pressure, cost-sensitive CN-sourced cylinders |
| E355 (+SR/+N) | EN 10305-1 (Europe) | 355-460 MPa | general European-spec cylinders, easier equivalence |
| 20MnV6 | EN 10305-1 | 470 MPa | wear-resistant general cylinders |
| 42CrMo4 (4140) | EN 10083 / AISI | ~550-900 MPa (QT) | when a Cr-Mo grade is specified by the OEM |
Choose 27SiMn when the design needs 800 MPa-plus yield at Chinese-source cost and the procurement accepts a GB-spec grade. Choose 42CrMo4 (4140) only when the OEM drawing names a chromium-molybdenum steel - the two are not interchangeable. For buyers in Europe, E355 under EN 10305-1 is the natural equivalent route; 27SiMn vs E355 is a standard-vs-standard decision, not a strength one.
Technique and tolerance:
|
Working method |
range |
ID |
H8 |
H9 |
H10 |
|
cold drawn |
25-250 |
30-50 |
+0.0390 |
+0.0620 |
+0.1000 |
|
cold rolling |
25-150 |
50-80 |
+0.0460 |
+0.0740 |
+0.1200 |
|
cold drawn-honed |
40-250 |
80-120 |
+0.0540 |
+0.0870 |
+0.1400 |
|
cold drawn-SRB |
50-250 |
120-180 |
+0.0630 |
+0.1000 |
+0.1600 |
|
cold drawn -polished |
40-250 |
180-250 |
+0.0720 |
+0.1150 |
+0.1850 |
|
cold drawn-polish-SRB |
50-250 |
as required |
as required |
as required |
as required |
Delivery condition and product form
| Decision | Options | Effect |
|---|---|---|
| Delivery condition | quenched & tempered vs as-rolled | moves yield by roughly 200 MPa and changes toughness |
| Bore finish | SRB vs honed | Ra, work-hardening and cost |
| Bore tolerance | H8 vs H9 | machining reserve and price |
All three routes deliver a usable cylinder barrel, but only the quenched-and-tempered SRB route combines the 835 MPa yield with a ready bore. The grade name alone decides none of this.
How 27SiMn SRB Tube Is Made
Mother-pipe production. 27SiMn is pierced and hot-rolled (or cold-drawn) to seamless tube per GB/T 17396, forming the pressure-carrying wall.
Quench and temper. The tube is austenitised, water-quenched and tempered to reach the 980/835 MPa strength with the required toughness and hardness.
Rough bore prep. The ID is bored or cold-drawn to bring the bore close to final size and correct gross ovality.
Skiving. A multi-tooth tool removes a uniform 0.1-0.5 mm layer, correcting roundness and taper and setting the target ID.
Roller burnishing. Hardened rollers apply 50-200 MPa radial pressure, cold-working a 0.1-0.3 mm surface layer, raising hardness 20-40% and bringing roughness to Ra 0.2 um.
Inspection. ID, wall, straightness, roundness and surface finish are checked; the heat number is traced to the EN 10204 certificate.
Quality Control and Testing
Heat-number traceability. Every tube is linked to its ladle analysis and EN 10204 3.1 certificate; 3.2 is available with surveyor attendance.
Dimensional checks. ID, wall thickness, straightness (0.3 mm/m) and roundness are measured against the H8/H9 and Ra 0.2 um requirements.
Mechanical verification. Tensile, yield, elongation, impact and hardness are confirmed per GB/T 17396 on the quenched-and-tempered condition.
Surface and finish inspection. Bore roughness is verified by profile or comparative sample; the work-hardened layer is confirmed by hardness traverse.
Third-party inspection. SGS, BV, TUV or DNV can witness testing and witness the certificate before shipment.
Why Source 27SiMn SRB Tube from GNEE
Grade and finish control. As a 27SiMn SRB tube supplier, we supply the full chain - 27SiMn mother pipe per GB/T 17396 through quenching, tempering and SRB boring - so the 980/835 MPa design basis is guaranteed, not assumed.
Size coverage. Bores from 40 mm to 500 mm (630 mm on request) in one grade reduce the number of suppliers you manage.
Documentation. EN 10204 3.1 as standard, 3.2 and third-party SGS, BV, TUV or DNV inspection available, with full heat-number traceability.
Service. Technical quotation within 24 hours, stock for common sizes, and consolidated shipping from Tianjin for export.
Packaging and shipping
Request a 27SiMn SRB Tube Quote
Send your grade (27SiMn, GB/T 17396, quenched and tempered), inside diameter x wall thickness, length and bore tolerance (H8/H9) - our technical team will confirm the specification and return a quotation with lead time within 24 hours. Contact GNEE today.
FAQ
What is a 27SiMn SRB honed tube?
A 27SiMn SRB honed tube is a quenched and tempered 27SiMn (GB/T 17396) seamless mother pipe whose bore is finished by skiving and roller burnishing. Skiving removes a thin layer (0.1-0.5 mm) to correct geometry; roller burnishing cold-works the surface to a near-mirror finish of Ra 0.2 um with an ISO H8 bore. It is a finished cylinder component, not a raw steel grade.
What mechanical properties should I design to for 27SiMn?
Design to the GB/T 17396 quenched and tempered values: tensile strength 980 MPa (142 ksi) minimum, yield strength 835 MPa (121 ksi) minimum, elongation 12% minimum, impact 39 J at 20 C, hardness 217 HBW maximum. Some suppliers quote 860/760 MPa for an as-rolled or normalised condition; those are not the hydraulic-service quenched and tempered values this tube is sold to.
Is 27SiMn the same as AISI 4140 or DIN 25CrMo4?
No. 27SiMn is a China-specific grade with no direct Western equivalent. AISI 4140 is a higher-carbon (about 0.40%) chromium-molybdenum steel and must not be substituted for 27SiMn. DIN 25CrMo4 is the nearest approximation but its chromium content differs, so treat it as similar, not equivalent. ASTM A519 only covers the mechanical-tubing supply route, not the grade identity.
Should I specify SRB or honed for my cylinder?
Choose SRB when you need a fast, cost-effective volume finish with a work-hardened bore (Ra 0.2-0.8 um, ISO H8) for mobile and industrial cylinders. Choose honed when the specification demands an intentional oil-retaining crosshatch for servo, proportional, or large-bore cylinders (Ra 0.2-0.4 um). Many buyers accept either provided the ID tolerance and Ra are met.
What internal diameter, tolerance and roughness can I order?
Standard finished bore (ID) ranges from 40 mm to 500 mm (1.6-20 in), with larger bores up to 630 mm available. Bore tolerance is ISO H8 (H9 as the economy option). SRB surface roughness is Ra 0.2 um or better; honed is Ra 0.4 um. Straightness is held at 0.3 mm per metre or better.
Can 27SiMn SRB tubes be welded?
Weldability is fair but the steel is hardenable (CEV about 0.45-0.52). Preheat to 150-200 C is recommended for thicker walls, and post-weld heat treatment may be needed. Because the tube is supplied quenched and tempered, confirm the welding procedure with your fabricator and request the WPS; do not assume a no-preheat condition.
Which standards apply to 27SiMn cylinder tubes?
The mother pipe follows GB/T 17396-2022 (hydraulic pillar seamless tubes, in force since 2023) and the grade is defined by GB/T 3077-2018. The finished bore tube is covered by GB/T 8713. Export orders often reference ASTM A519 or EN 10305-1:2016 (DIN 2391 has been withdrawn and replaced by EN 10305-1).
How do I write 27SiMn on a purchase order?
State: (1) grade 27SiMn with standard GB/T 17396; (2) delivery condition quenched and tempered; (3) inside diameter, wall thickness and length; (4) bore tolerance class H8 or H9; (5) surface finish SRB or honed with Ra; (6) straightness; (7) end condition; (8) certificate EN 10204 3.1; (9) third-party inspection if required. Never write the grade name alone.
