Information on the most widely used ASTM standards within the materials testing industry
EN 10232 Metallic Tube Full-Section Bend Test
EN 10232 is the European version of ISO 8491,defines a unified cold bend test for intact circular full-section metallic tubes, designed to quantify plastic bending ductility for tubes with outer diameter D ≤ 65 mm.
Test principle:
The core principle is cold full-section guided bending:

A straight, hollow, unfilled tubular specimen is clamped and wrapped around a precision grooved bending former with a defined groove bottom radius r. Continuous bending force is applied until the tube reaches the specified bend angle α laid out in relevant tube product standards. The test replicates real-world cold-forming bending loads, evaluating the tube’s capacity to sustain uniform plastic deformation without cross-section ovalisation or surface cracking.
Test Equipment required for EN 10232:
Specialised tube-bending machines (recommend UnitedTest Steel Pipe Bending Testing Machine ) are required; generic sheet bending apparatus cannot be used:
Anti-ovalisation design: The machine structure must restrict tube cross-section flattening (ovality) during bending to eliminate invalid deformation results.
Grooved bending former: The groove profile precisely matches the tube’s outer diameter D. The groove bottom radius r is specified by applicable product standards.
Tool tolerance impact: Variations in radius r tolerance, groove depth and groove ovality directly alter test pass/fail outcomes and must be tightly controlled.
Test Specimen Information
Geometry: Straight, unmodified segment cut from the original tube, retaining complete circular full cross-section (no slitting into strips).
Length rule: No fixed minimum/maximum length requirement; the specimen only needs sufficient length for secure clamping and full bending stroke on the machine.
Welded tube specimens: No pre-machining of weld seams before testing.
Key Test Parameters and stipulations:
| Symbol | Description | Unit |
|---|---|---|
| D | Outside diameter of tube | mm |
| T | Wall thickness of tube | mm |
| L | Length of test piece (before test) | mm |
| r | Inside radius at bottom of groove (former) | mm |
| α | Angle of bend | ° |
Details test procedure of the EN 10232 test:
1 Test Temperature
Testing shall be executed under ambient room temperature conditions (10 °C to 35 °C). The standard does not specify a strict controlled laboratory reference temperature unlike ISO 8491.
2 Bending Operation
Test the hollow tube without any internal filling (no sand, mandrels or fillers). Operate the tube bender to achieve full contact between the tube outer wall and the grooved former along the entire bending arc until the defined bend angle α is achieved.
3 Weld Position Requirement for Welded Tubes
Unless alternative rules are stated in product specifications, the weld seam must be positioned at 90° relative to the bending plane (aligned with the neutral bending axis) to avoid concentrated tensile/compressive stress on the weld joint.
4 Test Result Acceptance Criteria
Priority rule: Follow acceptance thresholds written in the corresponding European tube product standard.
Default criterion (no product-specific rules): The specimen passes if no cracks are visible to the naked eye without magnification tools; any observable surface crack constitutes test failure.
Applicable Industry Fields
Pressure vessels, boilers, heat exchangers, oil & gas pipelines, automotive tubing (exhaust/chassis), structural hollow sections, general mechanical engineering — any sector where tubes are field-bent or see bending loads in service.
Related standard:
| ISO 8491 | Metallic Materials - Tube (in Full Section) - Bend Test |
| IS 2329 | Method for bend test on metallic tubes (in full section) |
| NF A03-091 | Metallic materials. Tube (in full section). Bend test. |
| ISO 7438 | General bend test for flat metal strip/sheet specimens. |
| TCVN 5891 | Metallic materials. Tube (in full section).Bend test |
GOST 3728 | Steel Pipes. Bend Test Method |
| GB/T 244 | Metallic material—Tube—Bend test method |
| GB/T 32976 | Metallic materials—Tubes—Transverse bending test |
Related products and device
Related Standard
ISO 8491 define a unified bend test method for evaluating the plastic bending ductility of circular full-section metallic tubes, exclusively for tubes with outer diameter D ≤ 65 mm (product standards may narrow this diameter range further).
Main Industry fields: boilers & pressure vessels, oil & gas pipelines, automotive (exhaust/chassis tubing), heat exchangers, structural steel tubing, power generation (including nuclear).
ISO 7438 is a standard that specifies a method for determining the ability of metallic materials to undergo plastic deformation in bending. It is used to evaluate the flexural strength and stiffness of a material , The bend test shall be carried out in testing machines equipped with a bending device with two supports and a former; bending device with a V-block and a former; bending device with a clamp.
ASTM E290 Standard Test Methods for Bend Testing of Material for Ductility
ASTM E290 is a destructive mechanical test standard that evaluates the ductility and structural soundness of metallic materials (and welds) by subjecting specimens to controlled bending deformationASTM International. It is a widely used quality control and qualification method for metals, alloys, and welded joints across industries.
ISO 7801: Metallic materials -- Wire -- Reverse bend test
Specifies the method for determining the ability of wire of diameter or thickness 0,3 to 10 mm inclusive to undergo plastic deformation during reverse bending. The range of diameters of thicknesses for which ISO 7801 is applicable may be more exactly specified in the relevant product standard. The test consists of repeated bending, through 90 in opposite directions, of a test piece held at one end, each bend being over a cylindrical support of a specified radius.
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