Lankford coefficient

The r- value (also perpendicular anisotropy ) provides in material technology, a dimensionless measure of the anisotropy of plastic deformation in metal samples dar. The r- value can be determined in the uniaxial tensile test according to DIN ISO 10113.

Calculation

Calculated is the average r- value using the following equations:

• R- values ​​> 1: width direction is the main direction of flow
• R- value = 1: isotropy of the material

Typical R- values ​​for steels are in the range of about 0.8 to 2.2.

The isotropy of sheets is important for the behavior during deep drawing, for example the production of beverage cans or car body parts.

The distribution of r- values ​​on the sheet plane ( " earing " ) is represented by the planar anisotropy:

• Material testing