Abstract:Near-equiaxed fine grains with the average grain size of 1.21 μm of pure tungsten has been fabricated via high pressure torsion (HPT) at the temperature of 550 ℃, under a pressure of 1.5 GPa. The influence of HPT processing at various turning numbers on microstructure and micro-mechanical properties of sintered commercial pure tungsten has been investigated by means of EBSD and nano-indentation experiments. It was found that the pores in material were closed effectively, the grains were refined significantly and the ratio of high angle boundary increased rapidly after HPT processing. Moreover, when the strain was relatively low (at the turning number of 1), there was a preferred grain orientation along <101>, which weakened to disappearing with the strain increasing; when the strain was high (at the turning number of 5), some small dynamic recrystallites generated at grain boundary. In addition, the nanohardness and yield strength increase obviously as the strain increasing, which is due to pores closure, grain refinement, lattice distortion, dislocation density increase and high angle grain boundary formation; the combination of relative density, residual stress and high density dislocation, make the elastic modulus of HPT-processed samples higher than sintered commercial pure tungsten, but decrease slightly as the strain increasing during the processing.