ASTM E290 Complete Guide: Bend Testing Metals for Ductility, Span, Fixtures and Crack Evaluation
ASTM E290 is the standard bend test for the ductility of metals, and because it produces no number, it is easy to run wrong and still call the result a pass. The span left from the last job, a mandrel picked from a rule of thumb instead of the product specification, a burred edge, an angle read after springback, or a crack judged with a magnifier can each turn a pass into a fail or the other way round. This complete guide covers everything you need to run E290 properly: the four bend methods, specimen sizes and edge rules, the span formula C = 2r + 3t, mandrel and support selection, speed and alignment, the step-by-step procedure, angle measurement, how cracks are judged, a worked example with the force the fixture actually sees, E290 vs. ISO 7438, troubleshooting and a full FAQ, with videos from our lab.
It also covers equipment honestly: which guided-bend, wrap-around and semi-guided fixtures fit on a universal testing machine, when a Mark-10 tester is enough for thin strip and wire, when you need a Galdabini floor-standing or hydraulic frame for heavy plate, where an arbor press fits, and where extensometers do and do not add value.
For the standard reference page with the full method summary, the data sheet and downloads, see our ASTM E290 bend test page. This article focuses on setting up and running the test and choosing the equipment.
ASTM E290 at a glance
Full title: Standard Test Methods for Bend Testing of Material for Ductility. The current edition is E290-22.
What it measures: whether the convex (tension) surface of a bent specimen survives a defined bend without cracking. The result is pass or fail with a description of any cracks; no stress is calculated.
Four methods: guided bend, semi-guided bend, free bend, and bend-and-flatten.
What sets the severity: the bend radius relative to thickness and the bend angle, both taken from the product specification, not from E290.
Guided-bend span: C = 2r + 3t ± t/2, where r is the plunger radius and t the specimen thickness.
Specimens: full sections up to 38 mm (1½ in); flat specimens at a width-to-thickness ratio of 2:1 with a minimum width of 18 mm (¾ in), or 8:1 or more for thin sheet; edges rounded to ≤ 1.5 mm (≤ 3 mm on larger specimens).
Speed and temperature: no numeric values; bend smoothly, without shock, in the laboratory atmosphere unless the product specification says otherwise.
Angle: measured under load for guided and semi-guided bends; no correction for springback.
Evaluation: convex surface inspected with the unaided eye; fracture fails; cracks within one thickness of an edge are not counted.
Typical equipment: a universal testing machine with a guided-bend fixture sized for the force, interchangeable plungers, hardened supports and compression platens to finish 180° bends. See our bend testing fixtures.
What ASTM E290 measures and who uses it
E290 tests ductility by bending. A specimen is bent plastically around a mandrel, plunger or pin of a specified radius to a specified angle, and the outside of the bend is examined. The outer fibres are stretched by an amount set by the geometry: for a mandrel of diameter D and specimen thickness t, the surface strain is roughly t ÷ (D + t). A bend around a mandrel twice the thickness (2t) stretches the surface about 33 %; a 4t bend about 20 %; a 6t bend about 14 %. The product specification picks the mandrel so that sound material passes and defective material cracks.
That makes the bend test a very effective screen for problems a tensile test averages away: surface seams and laps, decarburization, laminations, inclusion stringers, embrittled heat-affected zones, poor weld fusion and lack of penetration. It is used for:
Steel plate, bar and shapes, through ASTM A370 and the product specifications that call it.
Reinforcing bar, where ASTM A615 and related specifications require bend tests around pins of specified diameter.
Weld procedure and welder qualification, through ASTM E190, AWS and ASME Section IX guided bends.
Sheet, strip, wire and spring material, for formability and quality checks.
E290 itself is a procedure: it defines the methods, specimen rules and evaluation. The product specification supplies the mandrel size, the angle, the number of specimens and the acceptable crack size. E290 has no precision and bias statement, because the result is an inspection, not a measurement.
The four ASTM E290 bend methods
Guided bend
The specimen rests on two supports a set distance apart and a plunger of defined radius pushes its mid-length down between them. Variants include the plain three-point bend with no die, and U-die and V-die arrangements in which the specimen is pushed into a die that completes the bend, often used for cold-rolled sheet. The guided bend is the workhorse for plate, bar and weld coupons, and it is what lab bend fixtures on a universal testing machine are built for.
Semi-guided bend
The specimen is bent against a mandrel or pin to a specified angle or inside radius, with the angle measured under load. E290 describes three arrangements: A, with one end held and the specimen bent around a pin or roller; B, thin sheet clamped in a vise and bent over with a mallet; and C, the specimen held against a mandrel while a roller wraps it around, which is what most labs call a wrap-around bend. Report it as semi-guided Arrangement C, since E290 does not use the term wrap-around.
Free bend
Force is applied only at the ends and nothing touches the inside of the bend. In one form the ends are brought together to 180° with the legs parallel at a set spacing; in the other, the specimen is closed flat on itself between platens, which is the more severe test.
Bend-and-flatten
A bend of roughly 180° is completed between platens until the legs are in contact along their length. It is used mainly for tube, pipe and some sheet products, and the evaluation includes the outside of the bend after flattening.
Which method applies is set by the product specification. Welded joints are usually tested by ASTM E190 or the weld code (AWS, ASME IX) rather than E290 directly, and ISO 7438 excludes welds altogether.
ASTM E290 specimen types and dimensions
Full sections: any product whose smallest dimension is 38 mm (1½ in) or less may be bent full-section. Rounds, hexagons, rebar and other shapes are normally tested this way.
Flat rectangular specimens: width-to-thickness ratio of 2:1 with a minimum width of 18 mm (¾ in); for thin sheet, 8:1 or more. As-finished steel products may use a 38 mm (1½ in) width.
Machined specimens: from stock over about 13 mm thick, machine to at least 13 mm (½ in) thick at 2:1; the tension face of plate is normally left as-rolled.
Edges: round the long edges to a radius of not more than 1.5 mm (1/16 in) on specimens up to 50 mm wide, and not more than 3 mm (⅛ in) on wider ones.
Length: long enough to bend to the specified angle without the ends fouling the fixture; E290 gives no formula. For a guided bend, about twice the span plus an allowance is a practical minimum.
Orientation: longitudinal specimens run parallel to the rolling direction, transverse specimens across it. Transverse bends of rolled plate are the more severe case. Always report orientation.
Number: E290 does not specify a count; the product specification does. One or two per orientation is common.
Specimen preparation
Cut, then remove the damage. Shearing and flame cutting leave a work-hardened or heat-affected edge. Machine or grind it away so the edge is not the weakest point of the specimen.
Round the edges to the radius limit. A sharp or burred edge starts cracks that have nothing to do with the material, which is why the standard ignores cracks near the edge.
Keep the tension surface as produced unless the specification says to machine it. Grinding the surface removes the very defects the test is meant to find.
Mark the specimen with heat, orientation and the face to be in tension, outside the bend zone.
Weld coupons: remove the weld reinforcement flush as the code requires, and mark the weld centreline so it can be placed at the apex of the bend.
Universal Grip does not make cutting dies for metal bend specimens, which are normally sheared or sawn and then machined. For thin sheet strip, the 26 kN arbor press takes hardened steel dies for cutting thin metal sheet; contact us if you want to discuss a die for a standard strip size.
Conditioning and test temperature
E290 has no conditioning requirement and no numeric test temperature: bends are run in the laboratory atmosphere. Two exceptions come from the product specification. Some specifications require aging before bending, or bending within a time window after heat treatment, for age-hardening or strain-aging materials. And some call for bends at low or high temperature, in which case the specimen and fixture go in an environmental chamber and the test temperature becomes part of the result.
Fixture geometry: span, plunger radius, hardness and lubrication
For a guided bend, the support spacing is tied to the plunger radius and the specimen thickness:
Span: C = 2r + 3t ± t/2, where C is the clear distance between the supports, r the plunger radius and t the specimen thickness. Written with the mandrel diameter D = 2r, it is C = D + 3t, the same expression ISO 7438 uses. Too wide a span lets the specimen bend to a larger radius than the mandrel; too narrow pinches it and raises the force.
Plunger and support radii: set by the product specification as a multiple of thickness. E290 does not choose them. Many weld codes use 4t for carbon-steel coupons and larger multiples for high-strength and some alloy steels; rebar specifications set pin diameters as multiples of bar size. The plunger radius should be within ± 5 % of nominal.
Hardness: supports and plunger must not deform. Hardened, ground rollers and plungers are the norm; any visible permanent deformation of the tooling invalidates the test.
Length: plunger and supports must be longer than the specimen is wide and stiff enough not to deflect.
Lubrication: permitted on the supports and plunger; report the lubricant, because friction changes the strain distribution.
Completing a 180° bend: after the plunger takes the specimen well past 90°, finish between platens with a spacer of thickness 2r between the legs, so the inside radius stays at r, or close the legs fully if the specification allows.
Our guided-bend fixtures are built around this formula, with roller supports on an adjustable span, interchangeable plungers in the radii your specification calls for, and mounting adapters for your machine. The ASTM E290 page lists the configuration and data sheet.
Test speed and machine requirements
Speed: E290 gives no numeric rate. Bend smoothly and without shock, at a rate suited to the process the material will see or, if that is unknown, consistent with safe practice. In a universal testing machine, a steady crosshead speed of a few tens of millimetres per minute is typical for lab coupons. ISO 7438 sets 1 ± 0.2 mm/s (60 ± 12 mm/min) of former displacement for disputed tests, a sensible default under E290 too. Record the speed you used.
Force capacity: the machine and fixture must carry the bend force with margin. It scales with the square of thickness, so plate coupons need far more capacity than tensile coupons of the same material. See the worked example below.
Stroke: enough plunger travel to take the specimen well past 90° before finishing between platens, typically several times the span.
Alignment: plunger parallel to the supports and square to the specimen axis, centred on the span.
Software: not required for a pass/fail bend, but a force-displacement record helps when investigating failures, and some machines can stop automatically at a calculated bend angle.
Safety: high-strength specimens can kick out of the fixture or fracture violently. Use a guard, an anti-roll bar where fitted, and keep hands clear.
Which testing machine for ASTM E290: Mark-10, Galdabini or an arbor press?
Bend force depends on thickness, width, span and strength, so the machine choice is driven by your heaviest specimen. Start with the force estimate in the worked example, then pick the machine.
Mark-10 test frames: thin strip, wire and small rounds
A Mark-10 motorized test frame runs guided bends in compression with a small bend fixture and suits QC on thin strip, foil, wire and small-diameter rounds where the force stays within about 6.7 kN:
300 lb (F305) and 500 lb (F505): 18 in (457 mm) of travel and speeds to 330 mm/min as standard. Enough for thin strip and fine wire.
750 lb (F755) and 1,500 lb (F1505): 32 in (813 mm) of travel, 10 to 600 mm/min as standard, and up to about 6.7 kN. A 1.5 mm × 15 mm steel strip on a 2t mandrel needs only about 1.6 to 2.3 kN.
All F-series frames hold speed to ±0.2 % and sample load at 5,000 Hz.
The small bend fixture comes in aluminum (2.5 kN) or steel (10 kN), with spans of 4 to 150 mm, 30 mm wide supports and interchangeable rollers from 1 to 12.7 mm diameter on a 5/8 in clevis, with adapters for other frames. Compare machine types in Mark-10 test frame vs. universal testing machine.
Galdabini universal testing machines: sheet, plate and weld coupons
For sheet and plate, weld coupons, certification work and labs that also run ASTM E8 tensile tests from the same heat, a Galdabini universal testing machine is the right tool:
Benchtop 25 kN, 50 kN and 100 kN: sheet and plate up to roughly 10 to 12 mm on moderate mandrels. A 12 mm coupon on a 3t mandrel needs about 21 to 31 kN, so a 50 kN frame.
Floor-standing 200 kN and 250 kN: thick plate, side-bend weld coupons and larger full sections, with room for a heavy bend fixture and a safety guard.
600 kN and 1,000 kN: heavy sections up to the 38 mm full-section limit, and labs that also pull large bar and plate in tension.
Hydraulic UTMs: high-capacity frames for steel mills and rebar labs that run tension and bend on one machine.
Size the bend fixture with the frame: our heavy bend fixture is rated 100 kN as standard and can be designed up to 600 kN for E290 and E190 work. See the universal testing machine buyer's guide.
Arbor press: occasional manual bends
Our 26 kN arbor press is our largest hand-operated press, and it is suited to 90° and 180° bend tests on steel samples as well as die cutting. For occasional checks on thin steel strip it is a low-cost option. It has no force or displacement record and the operator controls the rate, so for certification work, thicker material and consistent rates, use a testing machine. Ask us which bend tooling suits your specimens.
Quick comparison
Choose a Mark-10 for thin strip, foil, wire and small rounds within 6.7 kN.
Choose a Galdabini benchtop UTM for sheet and plate coupons up to about 100 kN, especially if the same frame runs E8 tensile.
Choose a Galdabini floor-standing or hydraulic UTM for thick plate, weld side bends, heavy full sections and rebar.
Use an arbor press for occasional manual bends on thin steel strip.
Bend fixtures for ASTM E290: guided, wrap-around and semi-guided
A bend test needs no tensile grips. The specimen sits in a fixture mounted in the compression space of the machine, and the choice of fixture follows the method and the force.
Guided-bend fixtures: two hardened roller supports on an adjustable span with a plunger on the crosshead. Our bend testing fixtures include the 50 kN medium fixture with spans from 20 to 1,000 mm or more and a choice of contact radii and widths, and the heavy bend fixture (100 kN standard, designable to 600 kN) used for E290 and E190.
Bearing-guided bend fixture: a guided bend fixture whose loading member runs in high-strength ball-bearing bushings, giving more uniform loading and helping prevent specimen slip and uneven loading.
Small bend fixture: the small bend fixture for strip, wire and thin sheet, 2.5 kN aluminum or 10 kN steel, spans 4 to 150 mm.
Wrap-around tooling (semi-guided Arrangement C): a mandrel with a roller that wraps the specimen around it, made to order for the mandrel diameters your specification calls for.
Semi-guided Arrangements A and B: one end held and bent over a pin, or thin sheet bent in a vise. These are often bench methods; ask us if you want a fixture for your machine.
Anti-roll bar: medium and larger fixtures can carry a retaining bar that stops the specimen rolling or buckling at high load.
Compression platens: to close 180° bends over a spacer, run free bends flat on themselves, and run bend-and-flatten tests.
Interchangeable rollers and plungers: so one fixture covers several thicknesses and mandrel sizes. Watch how rollers are changed on the small fixture in the video below.
Grips for the rest of the metals lab
Most E290 labs also run tensile tests from the same material, and those do need grips: wedge grips with flat and Vee jaws for plate, sheet and bar, and hydraulic grips for heavy bar and rebar. Fitting both to one frame lets the same machine run bend and tension certification. See how to choose tensile grips.
Do you need an extensometer for ASTM E290?
No. E290 is a pass/fail inspection, so no strain is measured and the standard does not require an extensometer or a deflectometer. Bend angle is measured on the specimen, not from an instrument.
Strain measurement still earns its place in a bend lab for three reasons:
The same frame runs ASTM E8 and A370 tension. Yield strength and elongation need an extensometer. A clip-on extensometer is the standard choice for metal coupons; a video extensometer measures to fracture without contact; XL long-travel extensometers cover long gauge lengths such as 8 in rebar. See how to run ASTM E8.
Load-deflection research. A deflectometer under the specimen gives a force-deflection curve during the bend, useful for comparing heats or studying springback. Our bend fixtures are available with a deflectometer holder.
Surface strain mapping. For research, a stereo video system such as the UGC-VE-4105 3D video extensometer can follow strain on a curved surface. It is a development tool, not something E290 asks for.
ASTM E290 guided-bend procedure, step by step
Step 1: Prepare the specimen to the product specification: cut to width and length, remove cut-edge damage, round the edges to the limit, and mark heat, orientation and the tension face.
Step 2: Measure the thickness and calculate the span, C = 2r + 3t. Set the supports and check the gap with a rule or gauge. Fit the plunger of the specified radius and inspect it and the supports for wear.
Step 3: Centre the specimen on the supports with the tension face down and the bend axis square to the plunger. For weld coupons, put the weld centreline under the plunger. Apply lubricant only if permitted, and record it.
Step 4: Bend smoothly at a steady rate until the specified angle is reached under load. If significant cracks appear before then, stop and evaluate.
Step 5: For 180° bends, remove the specimen and finish between platens with a 2r spacer between the legs, or close the legs as the specification requires.
Step 6: Measure the angle under load for guided and semi-guided bends, from lines projected along the flat legs outside the bend. Do not correct for springback.
Step 7: Inspect the convex surface with the unaided eye. Record any cracks: number, length, location and distance from the edge.
Step 8: Judge pass or fail against the product specification and report.
Angle measurement and springback
The bend angle is the angle through which the specimen has been bent, measured between lines projected along its straight legs. For guided and semi-guided bends it is measured under load; for free bends it is measured after the force is removed. When a bent specimen is unloaded it springs back: the angle opens and the inside radius grows. E290 does not allow any correction for springback. A 180° requirement is met at 180° under load, and a specimen that springs back to 172° after release has still met it.
On a universal testing machine, plunger travel can be converted to an approximate bend angle from the span, plunger radius and thickness, and ISO 7438 gives that calculation. It is useful for stopping at 90° or 120° automatically, but under E290 the reported angle is the one measured on the specimen. High-strength steels and aluminum alloys spring back much more than mild steel, which is one reason specifications use larger mandrels for them.
Evaluating cracks: what counts
Inspection: the convex surface is examined with the unaided eye. A defect that needs a magnifier to see is not a crack for E290 purposes.
Fracture: if the specimen fractures, the material has failed.
Edge cracks: cracks within one specimen thickness of an edge are not counted, because the edge is not representative of the material.
Corner cracks: not considered significant unless the product specification says otherwise or, if it is silent, unless they are larger than the specimen thickness.
Orange peel: surface roughening from coarse grain that does not open into the surface is not a crack; note it.
Acceptance: the allowed number and size of cracks come from the product specification. Weld codes commonly limit open defects to 3 mm (⅛ in), but that limit belongs to those codes, not to E290.
Worked example: span, strain and bend force
Setup. A transverse specimen of 12 mm carbon-steel plate is to be bent 180° around a 3t mandrel. At 2:1, the minimum width is 24 mm; a 30 mm width is used. Mandrel diameter D = 3 × 12 = 36 mm, so r = 18 mm. Span C = 2 × 18 + 3 × 12 = 72 mm, with a tolerance of ± t/2 = ± 6 mm, so the supports may be 66 to 78 mm apart; 72 mm is set. Edges are rounded to ≤ 1.5 mm. The bend is finished between platens over a 36 mm spacer (2r).
Surface strain. Outer-fibre strain ≈ t ÷ (D + t) = 12 ÷ (36 + 12) = 25 %. A 2t mandrel would give 12 ÷ 36 = 33 %, a 4t mandrel 12 ÷ 60 = 20 %.
Force. E290 reports no force, but the fixture and frame must carry it. Treating the specimen as a beam forming a plastic hinge under the plunger, F ≈ σ × b × t² ÷ L, with σ the flow stress, b the width, t the thickness and L the span. At a yield strength of 355 MPa: F ≈ 355 × 30 × 144 ÷ 72 = 355 × 30 × 2 = 21,300 N, about 21 kN. As the steel work-hardens toward 520 MPa, F ≈ 520 × 60 = 31,200 N, about 31 kN, plus support friction. A 50 kN benchtop frame and a 50 kN bend fixture are the right size.
Scaling up and down. Force grows with t² and falls with span. A 25 × 50 mm specimen on a 4t mandrel (D = 100 mm, span 175 mm) needs about 350 × 50 × 625 ÷ 175 = 62.5 kN at yield and roughly 90 kN with hardening, so a 200 kN floor-standing frame. A 1.5 × 15 mm strip on a 2t mandrel (D = 3 mm, span 7.5 mm) needs about 350 × 15 × 2.25 ÷ 7.5 = 1.6 kN, and about 2.3 kN at 500 MPa, which suits a Mark-10.
Result. The specimen reaches 180° under load without fracture. One crack 1.5 mm long is visible on the convex surface, 8 mm from an edge. Because 8 mm is less than one thickness (12 mm), it is disregarded. Report: pass, transverse, 30 × 12 mm, 36 mm mandrel, 72 mm span, 180°, no lubricant, edge crack 1.5 mm noted.
Typical bend requirements and precision
E290 has no typical values, because the result is pass or fail. What varies is the severity the product specification demands:
Weld coupons: commonly a 4t plunger for carbon steel, with larger multiples for high-strength and some alloy steels, bent 180°.
Reinforcing bar: bend pin diameters that grow with bar size and grade, with 180° bends on smaller bars and 90° on the largest. Check the current A615 table.
Steel plate, bar, sheet and strip: mandrel multiples of thickness that generally increase with strength and thickness, down to very tight bends (around one thickness, or flat on itself) for some formable sheet grades. Always take the value from the product specification.
There is no precision and bias statement in E290. Consistency comes from setting the span to the measured thickness, using hard, unworn tooling, preparing edges correctly, measuring the angle under load and inspecting without magnification.
Bend testing at high and low temperature
E290 runs in the laboratory atmosphere unless the product specification calls for another temperature.
For elevated or sub-ambient bends, mount the fixture inside an environmental chamber; ours run from −80 to +280 °C on Galdabini frames. Our high-temperature bend fixture uses heat-resistant alloy with long extension rods so the fixture sits in the chamber.
Soak specimen and fixture at temperature, bend in the chamber, and inspect after the specimen returns to room temperature.
See the temperature chamber buyer's guide.
What to report
The standard and edition, the bend method and arrangement, and the product specification.
Material, heat or lot, specimen orientation, size and type (full section, flat or machined) and edge preparation.
Plunger, mandrel or pin radius, support radius, span and lubricant.
Bend angle reached, measured under load (or after release for free bends), and test speed.
Cracks: number, size and location, including any disregarded edge or corner cracks and orange peel.
Pass or fail against the specification.
Common ASTM E290 problems and how to fix them
Span not reset: left from the last job instead of calculated as C = 2r + 3t for the measured thickness.
Wrong mandrel: a rule-of-thumb radius used where the product specification gives one.
Edge cracks from preparation: burred or sharp sheared edges. Remove the cut-edge damage and round the edges.
Springback "corrected": angle read after unloading on a guided bend. Measure under load and do not correct.
Magnified inspection: a loupe finds cracks the method says do not exist. Use the unaided eye.
Counting edge cracks: cracks within one thickness of the edge are not counted.
Worn or soft tooling: flattened rollers or plungers change the radius and invalidate the test.
Off-centre bend: the weld or the zone of interest is not at the apex.
Specimen kicks out: misaligned plunger or high-strength material. Fit an anti-roll bar and check alignment.
Frame too small: plate bends need far more force than tensile coupons of the same material. Estimate F ≈ σ × b × t² ÷ L first.
ASTM E290 vs. ISO 7438 and related standards
ISO 7438: the international bend test for metals. The span rule is the same (l = D + 3a ± a/2). ISO sets specimen width by thickness, caps thickness at 25 mm by machining one face, specifies 10 to 35 °C and 1 ± 0.2 mm/s in disputed tests, calculates the angle from former displacement, and excludes welds. E290 uses 2:1 or 8:1 widths, allows full sections to 38 mm, sets no speed or temperature, and measures the angle on the specimen.
ASTM E190: guided bend testing of welds, with a plunger-and-die jig. Weld codes such as AWS and ASME IX have their own bend jigs and acceptance limits.
ASTM A370: mechanical testing of steel products, which calls up bend tests and points to E290 for the procedure.
ASTM A615: deformed carbon-steel rebar, with bend pin diameters by bar size and grade.
ASTM E855: bend testing of flat spring materials, which measures a bending stress rather than ductility.
ASTM D790: flexural testing of plastics, which calculates a stress and modulus. It shares the three-point fixture layout but is a different kind of test; see 3-point vs. 4-point bend testing.
A fixture built for E290 also serves ISO 7438, EN ISO 7438 and JIS Z 2248 with the same span rule; the differences are in specimen preparation and reporting, not tooling.
Related metals tests
ASTM E8: tension testing of metals, usually run on the same frame. See how to run ASTM E8.
ASTM A370 and ASTM A615: steel and rebar certification, with tensile and bend tests. See rebar and steel testing: A615, A370, E8 and E290.
ASTM E23: Charpy impact testing of metals, on our impact testers. See the Charpy testing guide.
Our metals testing page and bend testing applications page cover the full lab.
Complete ASTM E290 equipment packages
Basic QC station for strip, sheet and wire
Mark-10 F1505 or F755 test frame for bends within 6.7 kN, or a Galdabini 25 kN benchtop UTM
Steel small bend fixture (10 kN) with rollers and plungers sized to your mandrel multiples
Compression platens to close 180° bends over a spacer
A 26 kN arbor press for occasional manual bends and thin-sheet cutting
Advanced plate, weld and certification lab
Galdabini 250 kN or 600 kN floor-standing universal testing machine, or a hydraulic UTM for heavy sections
Heavy guided-bend fixture from our bend testing fixtures range with interchangeable plungers, an anti-roll bar and wrap-around tooling to order
Wedge grips or hydraulic grips and a clip-on extensometer or video extensometer for E8 and A370 tension on the same frame
Environmental chamber for bends from −80 to +280 °C where specified
ASTM E290 FAQ
What is ASTM E290?
The ASTM standard test methods for bend testing of material for ductility. A specimen is bent around a mandrel of specified radius to a specified angle and the convex surface is inspected for cracks. The result is pass or fail with a description of any cracks, not a calculated stress.
What are the four bend methods in ASTM E290?
Guided bend (a plunger forces the specimen between two supports, including U-die and V-die variants), semi-guided bend (around a mandrel to a set angle, Arrangements A, B and C), free bend (force on the ends only) and bend-and-flatten.
How do I set the span for an ASTM E290 guided bend?
C = 2r + 3t ± t/2, where r is the plunger radius and t the specimen thickness, or D + 3t with D the mandrel diameter. A 12 mm specimen on a 36 mm mandrel uses a 72 ± 6 mm span.
What mandrel or plunger radius does ASTM E290 require?
None. The product specification sets it as a multiple of thickness, or of bar diameter for rebar. E290 requires only that the radius be within ± 5 % of nominal and the tooling hard enough not to deform.
What specimen size does ASTM E290 use?
Full sections up to 38 mm; flat specimens at 2:1 width to thickness with a minimum width of 18 mm, or 8:1 or more for thin sheet; as-finished steel may be 38 mm wide; machined specimens at least 13 mm thick. Edges are rounded to 1.5 mm or less, or 3 mm on specimens over 50 mm wide.
What is the bending speed in ASTM E290?
E290 gives no numeric speed. Bend smoothly and without shock at a rate suited to the application or to safe practice. ISO 7438's 1 ± 0.2 mm/s is a reasonable default.
How is the bend angle measured?
Under load for guided and semi-guided bends, from lines projected along the straight legs; after unloading for free bends. Springback may not be corrected.
How are cracks evaluated in ASTM E290?
With the unaided eye on the convex surface. Fracture is a failure. Cracks within one thickness of an edge are not counted, corner cracks count only if the specification says so or they exceed the thickness, and orange peel is not a crack. Acceptable crack size comes from the product specification.
How many specimens does ASTM E290 require?
E290 does not specify a number; the product specification does. One or two per orientation is common.
What force does an ASTM E290 bend test need?
Estimate it with F ≈ σ × b × t² ÷ L. A 12 × 30 mm carbon-steel specimen on a 72 mm span needs about 21 kN at yield and about 31 kN with work hardening, so a 50 kN frame and fixture. Thin strip needs only a few kilonewtons.
Can I run ASTM E290 on a Mark-10 tester or an arbor press?
A Mark-10 frame with a small bend fixture handles thin strip, wire and small rounds within about 6.7 kN. Our 26 kN arbor press can make occasional manual 90° and 180° bends on thin steel. Plate and weld coupons need a universal testing machine.
What is the difference between ASTM E290 and ISO 7438?
The span formula is the same, but ISO 7438 sets width by thickness, caps thickness at 25 mm, specifies 10 to 35 °C and 1 mm/s in disputes, calculates the angle from former displacement and excludes welds. E290 uses 2:1 or 8:1 widths, allows 38 mm full sections, sets no speed or temperature and measures the angle on the specimen under load.
Related reading
Get a complete ASTM E290 system
Universal Grip supplies everything for ASTM E290: guided-bend fixtures from the small bend fixture to heavy fixtures designable to 600 kN, interchangeable plungers and rollers, wrap-around tooling to order, compression platens for 180° and flatten tests, wedge and hydraulic grips and extensometers for tension on the same frame, environmental chambers, and testing machines from a Mark-10 tester to Galdabini benchtop, floor-standing and hydraulic universal testing machines. Tell us your thickest specimen, its strength, the mandrel sizes your specifications call for and your machine, and we will size the fixture and frame. Contact us for a quote.
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