Voitovich A. Dispersion over welded layers of the Fe-Cr-B-C system structure for increasing in their wear resistance

Machine parts that operate under abrasive actions and shock loads wear out intensively. A large number of materials have been developed to restore them, in particular, flux-cored wires (CW) that allow an increasing the doping level and built-up metal efficiency. The flux-cored wires, by means of which a metal is built-up for work in the conditions of abrasive wear under shock loads, are alloyed by expensive elements. It significantly affects the restoration cost. The built-up metal with CW of the Fe-Cr-B-C system is much cheaper. It and shoas satisfactory wear resistance at abrasive wear, however, the received layers crack due to under the action of shock loads, since the dendritic needle-shaped inclusions of borides are extricated because of the increased content of carbon and boron in the metal. The sharp ends of the needles inclusions serve as the tension concentrators, causing cracking under the shock loads. Wear resistance of the built-up metal and its resistibility to cracking increases with grinding of the boride inclusions. Therefore, to receive a wear proof layer, it is suggested to attach a vibration with a frequency of 100 Hz and an amplitude of 0; 70; 300 microns from the outside to a support plate during welding up of СW of Fe-Cr-B-C system. It has been investigated shown that horizontal vibration affects grinding of the boride inclusions; their average diameter is reduced from 175 to 5 microns, as well as the redistribution of phases, the amount of (FeCr)2B plastic phase increases. The mechanical characteristics change due to structural components dispersion, in particular, the deviating of data of micro-hardness decreases and its average value increases from 600 to 780 HV, Young's modulus and resistance of material to indenter movement increase. Wear resistance of the built-up metal on horizontal vibration with an amplitude of 300 microns has increased by 2.3-2.5 times under the wear of fixed and unfixed abrasive and by 2.8 times due to wear under shock loads. For restoration and strengthening of large-size parts, it is proposed to introduce PAM powder into the CW furnace charge for increasing in wear resistance of the built-up metal of the Fe-Cr-B-C system. This has contributed to dispersion of the boride inclusions, the average diameter of which has decreased from 70 to 5 microns. In the structure of the built-up metal of the Fe-Cr-B-C system, inclusions of the complex alloyed nitrides are extricated with the average size less than 1 micron. As a result, the average value of micro-hardness increases from 700 to 900 HV. Wear resistance of built-up metal increases by 1.5 times by the wear with of the fixed and unfixed abrasive and by 2 times by the wear under shock loads.