The causes of failure of the tangential rotary cutter bits of the road header during stonedrift in rocks of medium strength are analyzed in the article. It was revealed that the most typical cause of failure of cutter bits is premature wear of the toolholder (body) of the cutter bit. It is well known that the most effective way to improve the wear resistance is to increase hardness. The influence of the thermomechanical treatment of the material of the cutter bit toolholder on its hardness is studied. It was established that the thermomechanical treatment of the cutter bit toolholder material results in the increase of its hardness. It was found that the increase of material hardness is proportional to the increase of material strain intensity during thermomechanical treatment. It was concluded that the use of thermomechanical treatment can lead to the increase of both the hardness and wear resistance of the cutter bit material.

Influence of grain size on the mechanical and performance properties of metallic materials is analyzed. Methods for grain refining- equal channel angular extrusion (ECAE) is reviewed in the article. The method of equal channel angular pressing is described. Experimental data on the effect of sub-micron structures on hardness after ECAE samples of copper, aluminum and steel used in the manufacture of mining cutters (35HGSA) is presented.