Test Conditions of Leeb Hardness


There are several kinds of type of Leeb hardness test. They have different requirements for the test pieces.
According to the different impact energy we can put them into three categories. In each category, they are with the same or substantially the same test piece require.
Some of basic test conditions is shown as following, satisfying them is necessary for a correct and accurate measurement.

Minimun Weight of Test Piece


The weight of the test piece shall be considered when selecting the impact device to be employed.
Every type of impact device have its minimum weights. You may require rigid support and coupling to a thick, heavier non-yielding surface to resist the impact of the device.




Minimun Thickness of Test Piece
Leeb hardness is used by the "Impact - Rebound". The ideal test surface is with sufficient rigidity.
If the thickness is too thin, elastic behavior of the test piece will bring greater influence to the test results.






Minimun Radius of Curvature
Test pieces with curved surfaces may be tested on either the convex or concave surfaces providing that this radius of curvature of the specimens is matched to the size of the support ring. And the radius of curvature is not less than 50 mm. (2 in) for the G type impact device or 30 mm (13/16 in.) for other impact devices.







Surface Finish



The test surface shall be carefully prepared to avoid any alterations in hardness caused by heating during grinding or by work hardening during machining. Any paint, scale, pits, or other surface coatings shall be completely removed.
The surfaces to be tested shall be smooth. Failure to provide adequate surface finish will produce questionable test results. Coarse finishes will tend to lower the measured value. We recommend that the test surface should be machined or ground and polished to the left finishes at least.

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