Destructive Testing

The STF owned Testing Center offers destructive material tests e.g. tensile tests and metallographic examinations.

The laboratory is optimally equipped with an universal testing device of a maximum tensile and pressing load up to 40 tons and a semi-automatic preparation apparatus for metallographic samples.

Further to tensile testing and metallography we also offer Vickers hardness tests as well as impact testing. Moreover, we execute all necessary welding procedure tests and welder's qualification tests.

Our expert staff of highly qualified material testers for heat treatment and metal technology meets all requirements of our clients.

Tensile Test

With the tensile test, a sample with specified dimensions is slowly drawn in direction of the bar axis. The required force and distance are recorded.

The mechanical parameters, such as tensile strength in N/mm² or the yield strength, are calculated from sample cross section, force and distance …

With the tensile test, an oblong generally flat or cylindrical sample of predefined geometry is axially clamped into the tensile testing machine at both ends.

It is expanded at a continuous speed and elongated along the bar axis causing a contraction across the tensile direction.

During the process the tested material counters the deformation with different resistances. This is clearly visible on the testing chart. The applicable force of the testing machine changes accordingly.

The test is completed after fraction or after reaching a certain strain. During the entire test, force F affecting the test piece as well as the resulting length variation ΔL are registered, recorded and depicted in a stress-strain diagram. These values are dependent on the sample geometry.

Values, such as tensile strength in N/mm², strain, fracture strain, the yield strength or Rp 0.2, can be determined. Standardized and other sample forms and types, can be tested.

Impact Test

The impact test determines the impact strength in Joule showing the material "ductility".

The impact test also determines the material brittle fracture tendency.

The standardized notched sample is placed between two bearings in the correct position of the impact testing machine.

From a fixed position a hammer of a certain weight swings down onto the sample and smashes it.

The samples normally have room temperature but they can also be hammered at low temperatures.

We manufacture your standard samples from 2.5 mm to 10 mm.

Contact us for special geometries and non-standard samples, together we will find a solution.

Metallography

For you we create macro- and micro-sections. With macro-sections the grain structure of forgings or the characteristics of a weld can be examined.

With further, more sophisticated preparation methods we are able to determine the texture of the grain, purity, surface decarburisation and much more.

During cutting the samples are cooled to eliminate structural changes due to impact of heat. To ensure a perfect preparation of your samples, they are placed in a mold and covered with a 2-component epoxy resin.

After curing of the resin the sections are marked. With our automatic preparation device the samples are carefully ground under water cooling up to a granulation of 800. This granulation is sufficient for a macro-section of welds or for evaluating rolling directions.

When even higher precision is required, we polish your section with oxide polishing processes up to 0.06 µm to guarantee a clean and scratch-free surface

The section is ready for a purity analysis, an analysis for non-metallic inclusions or to determine the graphite allocation in the casting material. These tests are performed in high resolution under our microscope and the results are available in digital form.

If you are interested in the structure or the heat treatment condition, we etch your section with various acids and bases to display the structure.

Photos with up to a 1000-fold magnification are possible.

Hardness Testing

With our mobile hardness testing unit we perform hardness tests in our laboratory, at your premises or at site.

The handiness and mobility of our HV-testing-unit allows an examination of even inaccessible areas.

A hardness value of e.g. 285 HV5 specifies the mechanical resistancea material counters against the penetration of a harder indenter.

For Vickers hardness testing a pyramid-shaped diamond is used.

The hardness test can be considered a destructive as well as a non-destructive procedure, as it only causes very small dents not affecting the properties of most components.

Technological Testing

In addition to the tensile test we also perform technological tests, such as bending tests, flattening tests or expansion tests.

Technological tests do not determine values, such as tensile strength and hardness.

They are used to determine properties, such as bending strain or deformability.

They are frequently used to check the usability of a material.

Procedure-, Welding Production-, Welder's Qualification Tests

In close collaboration with the TÜV SÜD INDUSTRIESERVICE we perform the complete range of tests required for welders.

Procedure tests, welding production tests, and welder's qualification tests with sample processing and testing are performed quickly and reliably by one source.

Do you need a new or an extension of a welding production test?

Do you have a new welder in your company and require a welder's qualification test?

Contact us and together we will find a fast and easy solution!

Special Tests

Do you have components that require unusual testing procedures?

Do you want to examine the internal structure of your component without destroying it?

Are you unsure how or on what criteria, components are to be tested?

Contact us, together we will find a solution!