Testing service · Screw testing · Updated 15 September 2026
Screw testing: hardness and strength assessment
The screw testing you need depends on your question: do you want to check the hardness of a batch, examine the material near the surface or verify particular strength properties? Testawell offers screw hardness testing using Vickers, Rockwell and Brinell methods. We measure hardness in the core, at the surface and along a series of points in a polished cross-section. For suitable screws, we also use indentation plastometry to DIN SPEC 4864 to calculate comparative values for proof stress and tensile strength at individual test locations. Together, we choose a method suited to the material, screw shape and test objective.
For many steel screws and bolts, DIN EN ISO 898-1 sets out which properties are tested. Hardness, tensile strength, proof load and other requirements each need appropriate tests. A single hardness measurement or indentation test is therefore not enough to demonstrate that all requirements are met.
Testawell is currently not accredited to DIN EN ISO/IEC 17025. If you need an accredited test report, agree the tests with a laboratory accredited to perform them before placing the order.
Fig. 1 – Micro-indents for strength evaluation
What does indentation testing offer for screws?
Testing on the component: We measure on accessible surfaces. The preparation needed depends on the surface and shape of the screw.
Limited damage: Testing leaves small indents at the measurement locations. Whether the screw can be reused must be assessed separately.
Strength at individual test locations: We use the indent to calculate comparative values for proof stress RIp0.2 and tensile strength RIm, as well as a stress-strain curve.
Automation: Larger test series are possible. They require a suitable fixture and a test procedure that has been checked for suitability.
Suitability checked in advance: We assess whether the method suits the material, screw head shape and your question.
Where is screw testing used in practice?
Additional material testing during incoming inspection and larger test series.
Examining different property classes while keeping each screw traceable to its batch.
Comparing batches, heat treatments or coatings.
Additional measurements at individual locations to investigate complaints.
Automated testing directly in or beside the assembly or production line (inline/at-line).
Example: what results does indentation testing provide?
Strength metric
Value
RIp0.2
1211 MPa
RIm
1250 MPa
Example from internal Testawell measurements: the curve shows averaged comparative values at the locations tested. These values are not general acceptance limits and do not demonstrate compliance with a property class.
Fig. 2 – Screw after testing with five indents
How does indentation plastometry to DIN SPEC 4864 work?
Indentation plastometry to DIN SPEC 4864 starts by making a small indent in the screw. Its shape is measured optically in three dimensions. A computer model of the material (a finite element model) evaluates the permanent deformation. This produces flow curves, which show the relationship between stress and permanent deformation, and comparative values for proof stress and tensile strength. These values are calculated from the indent. They are not measured directly in a tensile test. The method causes limited damage. Before testing, we check whether the material is suitable and how the screw needs to be prepared. Official scope of DIN SPEC 4864:2019-11.
“With Testawell’s support we rapidly characterised a batch of small parts and detected differences. The selection ensures the best possible properties within the assembly.”
#Customer #Motorsport #ScrewTesting·
Measurements at individual locations help assess differences between batches or areas of a screw. For larger test series, we adapt the fixture, measurement locations and evaluation to the screw. A single comparative value is not enough to approve the screw for use.
The test report can include the calculated comparative values RIp0.2 and RIm, together with flow curves. It can also show how much the results vary between measurement locations. We identify the results in the report as comparative values from indentation plastometry. Whether a tested screw can be used afterwards must be assessed separately.
What information do we need for your screw test?
Send us a drawing or photograph and give the dimensions, material or property class, coating and batch details. Describe what needs to be tested, which edition of the standard applies and what type of test report you need. For hardness profiles or core testing, we also check whether the screws may be cut and prepared to provide a polished cross-section.
Request screw testing – we will agree the method and specimen requirements with you.
Frequently asked questions about screw testing
Which screw tests does Testawell offer?
We test screws using Vickers, Rockwell and Brinell methods. We measure hardness in the core, at the surface or along a series of points in a polished cross-section. For suitable screws, we also use indentation plastometry to calculate comparative values for proof stress and tensile strength at individual test locations.
Does indentation plastometry replace full testing to ISO 898-1?
No. Indentation plastometry provides comparative values at individual test locations. The agreed requirements for the screw under ISO 898-1 still apply. The prescribed tests must also be carried out. Hardness testing alone does not show that a screw meets all the requirements of its property class either.
Can a screw be reused after testing?
Indentation plastometry causes limited damage: it leaves small indents at the test locations. Whether the screw can then be used must be assessed separately for the component and its application. Screws that have been cut or ground to prepare a metallographic section cannot be reused.
What results does indentation plastometry provide?
Depending on the material and a suitable test procedure, the method provides comparative values for proof stress and tensile strength at the test location. It also provides flow curves, which describe the relationship between stress and permanent deformation. Under DIN SPEC 4864, the test indent is measured in three dimensions and evaluated using a computer model of the material (a finite element model).
Is Testawell accredited for screw testing?
Testawell is currently not accredited to DIN EN ISO/IEC 17025. If you need an accredited test report, agree the tests in advance with a laboratory accredited to perform them.
