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IS 1599:2019 is the Indian Standard (BIS) for metallic materials - bend and re-bend test for steel products. IS 1599 specifies the standard testing method for determining the ability of metallic materials to undergo plastic deformation through bending. It outlines the apparatus requirements, test piece preparation, and the procedure for bending without reversing the direction of force, followed by visual assessment for cracks.
Specifies methods for bend and re-bend testing of steel products to assess their ductility.
! IS 1599 only provides the testing method; the required bending angle and mandrel diameter must always be sourced from the specific product standard (e.g., IS 1786 for TMT bars).
! The bending force must be applied smoothly and continuously without any shock loads.
! A sample passes if no cracks or ruptures are visible to the naked eye on the outer (tension) surface after bending.
Specifies the fundamental method for determining the plastic deformation ability of metallic materials in bending.
ASTM E290-14(2022)ASTM International (US)
HighCurrent
Standard Test Methods for Bend Testing of Material for Ductility
Provides multiple test methods and apparatus configurations for bend testing metallic materials for ductility.
BS EN ISO 7438:2020BSI (UK) / CEN (EU)
HighCurrent
Metallic materials - Bend test
The UK and European adoption of the ISO 7438 standard, making it technically identical.
JIS Z 2248:2022JSA (Japan)
HighCurrent
Metallic materials -- Bend test
Japanese national standard specifying the method for bend testing metallic materials, technically aligned with ISO 7438.
Key Differences
≠IS 1599 explicitly defines a standardized re-bend test procedure (bending, thermal ageing, re-bending), which is not a feature of general international bend test methods like ISO 7438 or ASTM E290. This test is typically defined in product-specific standards internationally (e.g., ISO 15630-1 for rebar).
≠The ageing procedure for the re-bend test in IS 1599 specifies heating to 100°C for 30 minutes in an oven, whereas the comparable procedure in steel reinforcement standards like ISO 15630-1 specifies boiling in water for 30 minutes.
≠For examination of cracks, IS 1599 allows using a magnifying glass up to x3 magnification in cases of doubt. In contrast, ISO 7438 recommends a higher magnification range of x5 to x10.
≠ASTM E290 is more comprehensive in describing various test arrangements, including guided bend, free bend, and semi-guided bend test setups with detailed fixture requirements, whereas IS 1599 and ISO 7438 focus primarily on the three-point bend (V-block or U-bend) method.
Key Similarities
≈All standards share the fundamental principle of bending a test piece around a former/mandrel of a specified diameter to a prescribed angle to assess ductility.
≈The primary acceptance criterion across all standards is consistent: the absence of visible cracks on the outer (tension) surface of the bent specimen after testing.
≈All standards emphasize the importance of proper test piece preparation, including dimensions, surface finish, and the rounding of longitudinal edges to prevent premature failure from stress concentrations.
≈The key test parameters, such as the former/mandrel diameter and the bend angle, are not prescribed by the method standards themselves but are deferred to the relevant material/product standard in both IS 1599 and its international counterparts.
Parameter Comparison
Parameter
IS Value
International
Source
Test Type
Specifies both Bend Test and Re-Bend Test.
Specifies Bend Test only. Re-bend is typically in product standards.
ISO 7438:2020
Re-bend Test: Ageing Condition
Heat to 100°C, hold for 30 minutes, cool in still air.
Not specified in general standard. Product standards (e.g. for rebar) often specify boiling in water for 30 minutes.
ISO 15630-1:2019
Re-bend Test: Bending Angles
Initial bend to 135°, then re-bend by 20° (to an included angle of 115°).
Not specified in general standard. A common product requirement is initial bend to 90°, then re-bend by 20°.
ISO 15630-1:2019
Crack Inspection Magnification
With naked eye; magnifying glass (up to x3) in case of doubt.
With naked eye; magnifying glass (x5 to x10) can be used in case of doubt.
ISO 7438:2020
Test Piece Edge Rounding (Radius)
May be rounded to a radius not exceeding 10% of thickness (0.1t).
Shall be rounded to a radius between 0.1t and 0.2t (max 3 mm).
ISO 7438:2020
Distance between Supports (Three-point bend)
L = D + 3t (approx.), where D is former dia. and t is thickness.
L = (D + 2t) ± t/2
ISO 7438:2020
Applicable Material
Metallic Materials - Steel Products
Metallic materials (general)
ISO 7438:2020
⚠ Verify details from original standards before use
Key Values2
Quick Reference Values
standard test temperature10°C to 35°C
distance between supports limitD + 3a ± 0.5a
Key Formulas
L = D + 3a (Distance between supports, where D is mandrel diameter and a is specimen thickness or diameter)