The hardness measurements confirmed that investigated processing of Mg-AZ31 alloy strengthen the material. The micro-hardness test performed at two arrangements of the Knoop indenter longer axis, i.e. parallel to ED and parallel to RD, revealed anisotropy of mechanical properties of the examined pipe (Fig. 2). The Knoop’s hardness (HK) values were significantly higher for RD orientation of the longer axis of intender in comparison to the ED orientation of longer intender’s axis. For RD intender orientation average values of the HK were 66.4, 70.8, 86.5, 90.5, and 91.7 for deformations 0%, 5%, 13%, 28% and 50%, respectively.