Destructive testing; materials tensile, compression, bending, etc. It is the inspection methods applied to determine the resistance and strength it will show against permanent shape changes.
It is useful to take a brief look at the history of the process in order to better understand the necessity of destructive tests to be applied to welded joints and other materials. Towards the end of the 1940s, with the beginning of the maturity of the 2nd Industrial Revolution, the manufacturing industry has become an important actor of international trade. Manufacturers and countries have established common standards in order to collect the quality of the products produced in a common language and scale and have started to subject all manufactured parts to these common standards.
The same standards are also used in buildings in our country and their use becomes mandatory day by day.
According to the requirements specified in the project specifications, additional tests may be requested or one or more of the tests we will mention may be requested.
The main ones are;
- Tensile Test
- Charpy Impact Test
- Fracture Test
- Hardness Test
- Bending Test
Tensile Test: Tensile testing, which can be performed with the transverse or longitudinal options, is applied to a sample representative of manufacture. The preparation criteria of the tensile sample are detailed in ISO 4136 (Transverse Tensile Test) and ISO 5178 (Longitudinal Tensile Test) standards.
Tensile testing is basically the application of tensile forces to the prepared sample in the direction of certain axes and the transformation of the deformation reactions of the material into data.
The tensile test in the section concerning welded manufacturing enables us to obtain the yield strength and tensile strength of the weld metal in MPa (N / mm2) and to determine the suitability of the weld metal to the base material. The weld metal is expected to be 5-10% stronger than the base metal, although it varies according to the static and dynamic load variability of the structure. According to the standards, it is sufficient for the weld metal to have at least as much yield and tensile strength as the base metal.
The% elongation value is also obtained as a result of the tensile test. The% elongation rate indicates the elongation ability of the tested material or weld metal.
Bending Test: It is the transformation of the deformation reactions that it changes against the force applied to the middle of a flat sample fixed on two supports without changing direction on a single axis. Preparation and application criteria for the bending test are detailed in ISO 5173 standards.
The purpose of the bending test is to determine whether the regions of the welded region subjected to bending moment are suitable for the predicted static dynamic calculations and the base material.
Macro Structure Test: The macro images of the samples cut and prepared from the test piece according to ISO 17639 are evaluated according to the same standard.
It is carried out in order to determine the penetration capability of the welded joint, the geometry of the weld seam and its suitability.
Hardness Test: Samples prepared from the main material, heat affected zone (ITAB (HAZ) and weld metal according to EN 1043-1 are subjected to hardness test with HV10 load.
Although the permissible hardness values for steel structures vary according to the type of main material, they are specified in detail in the EN ISO 15614-1 standard.
Hardness is not a direct function of yield and tensile strength. However, it has an organic relationship with fragility. For this reason, it is a very important data for steel construction productions. It is imperative that the hardness results are within the scope of the standards specified.
Charpy Impact Test: Charpy impact test is a test method applied to determine the transition temperature (ductile-brittle) of materials. The summary principle is used to determine the resistance of a material to fracture in Joules at a specified temperature.
In application to weld metal, compatibility with the base material is sought. The charpy impact strength results of the weld metal and heat affected zone (ITAB / HAZ) should be at least at the base material level.
ISO 9016 and ISO 148-1 standards include other details about sample preparation and charpy impact test application.
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