Hardening of parts of agricultural machinery with laser microalloying
2018
Pastukhov, A., Belgorod State Agricultural Univ. named after V. Gorin (Russian Federation) | Sharaya, O., Belgorod State Agricultural Univ. named after V. Gorin (Russian Federation) | Vodolazskaya, N., Belgorod State Agricultural Univ. named after V. Gorin (Russian Federation) | Minasyan, A., Belgorod State Agricultural Univ. named after V. Gorin (Russian Federation)
The work presents researches in the microstructure of surface layers after laser hardening of C 45, laser processing with pre-printed slip coatings, as well as after the complex treatment, which includes plasma welding and laser processing. The studies established the presence on the surface after modification three zones: the zone of welding – transition zone with a pronounced needle-like fine structure and framework with a ferritepearlite structure. Electron microprobe analysis carried out on the scanning electron microscope TESCАN VEGА//LSU showed the presence in the melted layer increased content of tungsten in the sample with HS 18; tungsten, vanadium and molybdenum in the sample with HS 5-6, as well as tungsten, cobalt, chromium and vanadium in the sample with HS 13-0-4-5. As the distance from the deposited layer in the transition zone and the original C 45 there were observed the disappearance of peaks of the alloying elements and the increase of the content of iron, silicon and carbon. The results of measurement of microhardness for all studied samples showed that the microhardness reached the maximum values of up to 16000 HV, when welding with powder HS 18 and the height of the laser head l = 15 mm; to 14720 MPa, when welding with powder HS 5-6 and the height of the laser head l = 20 mm; and 22400 HV, when welding with powder HS 13-0-4-5 and the height of the laser head l = 15 mm, which exceeds the microhardness of C 45 in the initial 8-11 times and 3-4 times in comparison with laser treatment of C 45 with no preliminary welding. The presence of a dense layer with high microhardness indicates that the method of plasma micro alloying and subsequent laser treatment can be used to restore worn parts with a sharp increase in the microhardness of the surface, and to process new parts for their surface hardening. The choice of a particular composition for plasma deposition and subsequent regimes of laser treatment depends on the specific operating conditions of the modified products of C 45.
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