The cause of the uncertainty of the elastic limit

The uncertainty of the elastic limit of metallic materials may cause inconvenience for the designers, therefore, the conventional yield strength is used for dimensioning in engineering practice. Today, it is not yet possible to measure the elastic limit with acceptable accuracy, since the elastic limit of every sample varies, due to the microstructure of polycrystalline materials. In this paper we try to confirm that the elastic limit can be considered only as a theoretical material property and to determine the reason for the uncertainty of the elastic limit. We found that the anisotropy of the elastic modulus very strongly influences the uncertainty of the elastic limit of the materials. These uncertainties cause problems during manufacturing, for instance in cases where the surface roughness is an important requirement, because the quality of the surface roughness is degraded by this phenomenon.