Also in the Knowledge Center
Testing Methods / Purpose / Procedure / Responsible Party
| Testing Method | Purpose | Procedure (Brief) | Typically Responsible |
|---|---|---|---|
| Visual inspection | Quick check of flash; Surface; Length | After every weld: Flash fully closed all around; Bright/shiny; Stud nominal length | Operator |
| Bend test (60°) | Proof of weld zone integrity | Before shift start: Min. 3 samples — weld and bend to 60°; No crack/fracture in weld zone and HAZ | Operator / Welding supervisor |
| Torque test | Control of threaded stud connection | Apply test torque; Document limit values | Operator / QA |
| Tensile test | Determine tensile strength / Yield strength | Stress specimen to fracture (DIN EN ISO 6892-1) | Test laboratory / QA |
| Hardness test | Detect brittleness / Microstructure effects | Indenter + defined load; Determine hardness value | Test laboratory / QA |
| X-ray / Radiographic inspection | Detect pores / Internal defects | Radiographic examination; Defect ratio limited per applicable code | Test laboratory / Welding supervisor |
| Macro section | Visualise weld structure | Prepare cross-section; Assess weld seam / Penetration | Test laboratory / QA |
Frequently Asked Questions on Testing Methods
Which testing methods are available for stud welding, and which are relevant for the operator?
Inspection of the weld in stud welding is essential. Unlike other welding processes, all testing methods (except for visual inspection) are destructive. For the operator, only visual inspection and bend testing are generally relevant, and in some cases torque testing as well. Other methods such as X-ray inspection, macro sectioning, tensile testing, and process monitoring are the responsibility of the welding supervisor or external inspection bodies.
What must be considered during visual inspection after each weld?
The operator must carry out a visual inspection after every weld. The weld bead should always be completely closed all around and have a bright, shiny surface. After welding, the stud should measure its nominal length. This simple yet important check provides an initial indication of the weld joint’s quality.
When and how is the bend test performed?
The bend test is a reliable standard procedure in destructive materials testing and is carried out in accordance with DIN EN ISO 7438. It examines whether and at what bending stress the weld zone of a test specimen begins to crack.
Time of Testing
At the start of every shift, the operator is required to weld at least three studs and subsequently bend them by 60°. Following a visual inspection, the result must be properly documented.
Ideally, the stud can be bent to the standard-defined bending angle without any visible weakening of the weld zone occurring. The following methods are available for carrying out the test:
Hammer – manual bending by striking the stud
Pipe – manual bending using leverage
Hydraulic press – mechanical bending
⚠️ Regardless of the method used, occupational safety regulations must be strictly observed.
Assessment
The test is considered passed if neither a fracture nor a crack is detected in the weld zone or heat-affected zone.
Benefits of the Bend Test
Although the bend test primarily serves to evaluate the welding process itself, tests carried out on a random and regular basis provide a reliable database, which can offer protection against legal disadvantages in the event of a dispute. A prerequisite is always a specimen manufactured in accordance with the applicable standards.
What is the purpose of X-ray inspection in stud welding?
Radiographic testing is mainly used to detect porosity in the weld joint. Depending on the applicable standard, defects in the stud cross-section may not exceed 5% or 10%. This inspection is carried out by the welding supervisor or external testing bodies and provides insight into the internal quality of the weld.
When and why is hardness testing used in stud welding?
Hardness testing makes it possible to assess the resistance of a stud weld in terms of strength and toughness. An indenter with a defined load is pressed into the weld zone – the size of the indentation and the required test force determine the hardness value. This method is used primarily when a component requires official acceptance as part of quality assurance.
What is a tensile test and what is it used for?
The tensile test in line with DIN EN ISO 6892-1 determines the tensile strength and yield strength of a component. Two key pieces of information for assessing quality. The specimen is stressed such that it initially buckles and then breaks. While the result of a tensile test merely provides an indication of the quality of the specimen, it allows indirect conclusions to be drawn as to the behavior of the finished component in its installed state. Consistent sampling allows potential deviations from the defined tolerances to be identified early on.
Technical Resources
Our technical documents provide you with welding parameters, standards overviews and quality guidelines for various materials and industries – as a basis for norm-compliant welding results.
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