Rolling of Refractory Metals on Four-Roll Passes Rolling Mills

Drop and rotary forgings of molybdenum or tungsten rods and wire rods requires a great number of operations accompanied by significant losses in expensive metals and low quality of half-finished products. Therefore, it is of great importance to develop new effective methods as well as the appropriate equipment for high-quality treatment of molybdenum, tungsten, and their alloys. The paper presents one of the methods—multi-pass rolling with multi-sided reduction of powder sintered blocks. Intensive three- or four-sided reduction of the block leads to a favorable strain-deformation conditions at the point of the applied deformation allowing to obtain the appropriate scheme of that state of the material. As a result, the plasticity of the rolled material increases and its cross-flowing slows down. High plasticity of the material allows to increase the degree of multi-sided reduction of rods or stocks and, therefore, to reduce the total number of treatment operations, to reduce the losses of metals, and to improve the quality of rolled products and their mechanical characteristics. Slowing down the cross-flowing of the metal during multi-sided reduction of its blocks in the process of rolling allows for a more effective deformation, low energy consumption, and cut number of block passes. Thus, four-sided reduction gives the most favorable scheme of the strain-deformation state of the material under the condition of multi-sided, nonuniform reduction of the blocks in the process of rolling.