Resistance to bending

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Resistance to bending

An extremely important feature of reinforcing steel is its ability to maintain the desired physical properties after bending. Execution of the bend causes the reinforcing steel to become plasticized, the impact of this plasticity on the work of the whole rod is evaluated. To this end, the following two tests are performed.

Bending and re-bending test

In order to perform bending test with re-bending, the steel sample is first bent by 90°. The diameter of the mandrel on which bends can be made are strictly defined in the standard and are - depending on the diameter of the rod under test - from 4d to 8d (where d - the diameter of the rod under test). Subsequently, the sample is aged, i.e. heated to 100° C, kept at this temperature for one hour and then cooled to room temperature in natural conditions. In the last step, the sample is deflected by an angle of min. 20°. If no damage visible to the naked eye appears on the surface of the sample, it is considered that it has passed the bending test with deflection positively.

Bending test with stretching

A bending test with a static tensile test is performed for bars with a diameter of d 16 mm. It consists in bending the rod by 90° (while maintaining the requirements as in the bend test with bending), and then straightening and subjecting to a static tensile test. The condition in this test is that the test sample meets the basic required strength and strain properties: Re, Rm/Re, A5 and Agt.