What Is The Steel Structure Leeb Hardness Tester?

Steel structure Leeb hardness testing refers to, in the engineering field inspection using Leeb hardness tester to detect the tensile strength of steel for construction, is a non-destructive testing method.
The test method can be presumed that the tensile strength of steel sections and reinforcing bars in reinforced concrete for steel structure in industrial and civil buildings, but it is not applicable to the testing of construction steel with obvious differences between the surface layer and the internal quality of the steel, or internal defects. The instrument used for the test is a Leeb hardness tester.

Leeb hardness tester working principle is to specify the quality of the impact body in the spring force, with a certain speed vertical impact on the surface of the specimen, to impact the body at a distance of 1mm from the surface of the specimen rebound speed and impact speed ratio to indicate the hardness of the material.

The methods for metal hadrness testing:

1)Single sample testing

Applicable to individual columns, beams, rods, supports and other steel components, or a single reinforcing bar in the concrete, the conclusions of the test shall not be extended to the untested components and the scope of the test.

2)Bulk samples testing

It is suitable for testing the tensile strength of steel or concrete reinforcement in the same test batch of steel components.

1. The measured area should be selected so that the Richter hardness tester in the horizontal direction to detect the hardness of the steel surface. When this requirement can not be met, you can let the Richter hardness tester in the non-horizontal direction to detect the steel surface.

2. A single component detection, each of the number of measurement area should not be less than 5, for the length of less than 4.5m, and the other direction of the size of less than 0.3m components, the number of its measured area can be appropriately reduced, but should not be less than 3.
3. For batch samples of the test, each member of the number of measurement area shall not be less than 3.
4. Before testing the need for steel surface treatment, completely remove the surface coating, oxidized skin, dirt or other surface irregularities, the surface can not have lubricants. In the treatment process should be avoided due to the heat caused by changes in steel hardness.
5. The measured area surface roughness Ra should not be greater than 1.6um.
6. The use of D impact device detection components, steel thickness should not be less than 10mm, should not be less than 8mm; the use of C impact device detection components, steel thickness should not be less than 5mm, should not be less than 3mm; for the surface of the surface for the concave, convex cylindrical surfaces and other curved surfaces of the components, the surface radius of curvature should not be less than 30mm.
7. The test site should be selected in the part of the vertical support, should be avoided to test the part of the vibration generated by the lack of rigidity. The fluttering of the bullet when the thin-walled, small components should be fixed.

1. Testing surface grinding treatment
Richter hardness value measurement, should be steel or steel surface grinding treatment, available steel file or angle grinder and other equipment to polish the surface of the components, remove surface coatings, oxidized skin, dirt or other surface irregularities, and then coarse and fine sandpaper sandpaper until the surface of the components to reveal the luster of the metal. Each measurement area of steel grinding area should not be less than 30 x 30mm2, concrete reinforcement measurement area should not be less than 10 x 50mm.
2. Roughness value measurement

After grinding with a roughness measuring instrument to measure the roughness value of the test surface, the measurement should not be less than 5 times, take the average. Each reading is accurate to 0.01um. test surface roughness should be less than 1.60um.
3. Hardness test, should be carried out in accordance with the following procedures:

a) push down the loading sleeve or otherwise lock the impact body;

b) the impact device support ring pressed firmly on the sample surface, the direction of impact should be perpendicular to the test surface;

c) smoothly press the impact device release knob;

d) read hardness values.
4. For the surface for concave, convex cylindrical surface and other curved surfaces of the components, its surface radius of curvature is less than 50mm, should be installed to support the ring, to ensure that the detection surface and the impact device does not produce relative motion between the detection surface and the surface of the support ring should be clean, free of oxidized skin, lubricants, dust and other contaminants.
5.The measuring point in the range of uniform distribution, any two indentation center distance should be greater than 4mm, any indentation center from the edge of the specimen distance should not be less than 5mm. The same test point can only be tested once. Each test area should be tested 9 values, each point of the Richter hardness value accurate to 1.