Abstract: This paper reports the experimental studies and theoreticalanalyses on axial splitting and curling of A3 steel tubes with differentthickness on a conical die. Seven groups of metal circular tubes, withdiameter D=54.4\,mm, are used as the text specimens. The force-compressioncurves and deformation modes of specimens are recorded. Three energydissipation mechanisms are involved: tearing energy, plastic bending energyand friction energy during the specimens deformation. Theoretical analysesfind that the influence of tube-thickness on the ratios of tearing energy andthe plastic energy to the total energy is considerable and on the ratio offrictional energy to the total energy is slight.