GB/T 15825.5-2008 is a Chinese recommended national standard that describes a bending test used to evaluate the bend formability of sheet metal.
It is commonly referenced when qualifying material for stamping and forming, comparing supplier lots, or troubleshooting cracking during bending operations. If you need help matching the cited edition to your material thickness range and reporting requirements, talk with our team.
GB/T 15825.5-2008 — 金属薄板成形性能与试验方法 第5部分：弯曲试验 / Sheet metal formability and test methods – Part 5: Bending test
This standard is part of the GB/T 15825 series for sheet metal formability. Part 5 focuses specifically on bending formability and how bending performance is expressed and reported for thin sheet materials.
Because bend formability is strongly affected by thickness, rolling direction, edge condition, tooling radius, and inspection criteria, equipment selection and fixture setup should be aligned to the same assumptions used in the standard and in your customer or internal specification.
Quick Definition
GB/T 15825.5 defines a laboratory bending test for sheet metal where the outcome is commonly expressed as a minimum bend capability using a bend-radius-based index (often reported relative to sheet thickness) under specified test conditions.
What This Standard Covers
This document covers a bending test method intended to characterize whether sheet metal can be bent to a defined severity without unacceptable cracking or surface rupture, and how to report the result in a comparable way.
In practical terms, it addresses: specimen orientation and preparation expectations, bend tooling/geometry concepts, bending execution, inspection for cracking, and reporting of the bend result as a formability indicator.
Why This Standard Matters in Testing
Bending is one of the most common strain paths in sheet metal fabrication. A standardized bend test helps teams compare lots and suppliers, verify process changes, and reduce the risk of in-production cracking—especially when material strength increases and allowable bend radius becomes more restrictive.
For QA/QC and procurement, a GB/T 15825.5 bend result can serve as a simple acceptance metric tied to forming risk. For R&D and process engineering, it is often used alongside other formability metrics to explain failures and guide tooling-radius decisions.
Common Materials, Product Types, or Applications Covered
This bending test is used for metal sheet products where bend cracking is a known risk. Typical usage includes carbon steels and alloy steels, stainless steels, and nonferrous sheet used in formed components.
Common application areas: stamped brackets and housings, bent flanges, formed channels, appliance and enclosure sheet, automotive and general industrial formed parts, and incoming inspection for sheet/coil used in bending-heavy geometries.
Common Test or Verification Workflow
Most laboratories use GB/T 15825.5 in a workflow that ties the bend outcome to a material qualification, a lot release, or a forming-process validation.
Common workflow: prepare and identify specimens (including direction relative to rolling direction when required); select a bend configuration and bend radius series; perform bending under controlled, repeatable conditions; inspect the bend zone for cracking; report the bending performance index using the convention required by the standard and the purchase/specification requirement.
Practical caution: edge quality and surface condition can dominate bending results. If your goal is to represent a production process, align specimen cutting/deburring and inspection criteria to the same expectations used for the part.
Equipment Commonly Used for This Standard
GB/T 15825.5 is typically run using a controlled bending setup capable of applying a repeatable bend using defined tooling geometry.
Common equipment: a universal testing machine or hydraulic press with a bending fixture; bend tooling or mandrels across a range of radii; supports/anvils appropriate to the fixture type; basic dimensional tools for thickness measurement; and visual inspection aids (lighting and magnification) for crack detection.
Equipment-selection tip: when the standard (or your internal requirement) is expressed as a minimum bend radius relative to thickness, the practical requirement is often a well-defined set of radii and a fixture that maintains alignment and consistent contact to avoid adding unintended severity.
How to Read This Designation or Revision
GB/T indicates a recommended (non-mandatory) national standard of the People’s Republic of China.
15825 identifies the series covering sheet metal formability and test methods, and .5 indicates Part 5 within that series (the bending test).
-2008 indicates the year of issue for this edition. This edition is listed as current and it replaced an earlier GB/T 15825.5-1995 edition, so test conditions and reporting details may differ depending on which edition is cited in a contract or drawing.
Related Standards, Methods, or Frameworks when useful
GB/T 15825.5 is commonly used alongside other formability evaluations within the GB/T 15825 series, especially when a project needs more than one index to characterize stamping and forming risk.
In procurement and customer specifications, bend requirements may also be paired with tensile-property requirements and product specifications for the specific alloy/temper/grade being purchased. When multiple documents are referenced, the controlling acceptance criteria should be identified explicitly (edition, specimen direction, and crack acceptance definition) to avoid mismatched interpretations.
Request a quote for bending-test equipment and fixtures
If you are outfitting a lab for sheet metal bend testing or adding a bend-radius tooling set to support GB/T 15825.5 reporting, you can request a detailed quote for a configuration matched to your thickness range, inspection needs, and throughput.
