OBRABOTKA METALLOV

 Welded rail joints are integral part of continuous welded rail. However, its reliability during the operation is no sufficiently high. The influence of the grinding process of aluminothermite welded rail joints, performed at different values of the residual post-weld temperature of the weld, on the physical and mechanical properties and roughness of the rolling surface is investigated. The process of grinding is carried out at different values of residual post-weld temperature. The interval of post-weld temperatures in the zone of grinding of welded joints was 600…850 ° C. It is established that, different temperature regimes, when performing the technological operation of grinding aluminothermite joints, lead to the formation of non-identical mechanical properties of the metal surface of the rail head in the weld zone. Grinding at a residual post-weld temperature of the weld surface of 850 ? or 600 ? allows the highest hardness values of 33 ... 36 HRC to be achieved, while grinding at a residual temperature of 800 ? or 700 ? results in a decrease in the hardness of the weld metal to 25 ... 30 HRC. However, after grinding when the residual post-weld temperature is 800…700 ? hardness of the welded metal decreases from 25 to 30 HRC.  Reducing the temperature of the metal surface of the railhead before grinding from 850 ? to 600 ? allows reducing the roughness of the rolling surface from 2.5 microns to 0.7 microns. The received results indicate that the highest values of hardness and surface finish can be reach when temperature of rail welded joint head metal is 600 ? during grinding when carrying out process of welding. It can be claimed that grinding of rails welded joints in a hot state is the perspective direction in the field of improvement of post-weld technological process of welded joints.

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