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The comparative accelerated tests were realized. The break-and wear-resistance of journal-bearing connection was obtained. Crankshaft journals were renewed by the laser built-up welding with self-fluxing Cr-B-Ni-Si powder of the different composition. Available data were analogous to the characteristics of the new connection. The rising of the coating hardness doesn't lead to the improvement ofthe performances. ThTRODUCTIONLaser built-up welding has any advantages over the other methods of detail repairing. So the electro-arc built-up welding leads to the overheating of details, their bending and to the large roughness of surface. The different methods of spraying and metallization don't overheat details, but lead to porous coatings weakly connected with basic metal. Laser built-up welding hasn't these lacks and allows to get porrousless corrosion-proof coatings, firmly connected with the base, not demanled the additional face hardening, and allows to reduce significantly the allowance for the finished treatment by grinding. The locality and concentration of the laser influence assures the minimum heat contribution in details and exepts their overheating and bending. PREPARATION OF SPECIMENS.Specimens-rollers imitated the cranshaft journal had 52 mm diameter, 12 mm width and were made of steel 45. They were built-up welded by powder of Cr-B-Ni-Si -alloies. After that rollers were grinded and polished to the roughness Ra<:=O,1 m. Laser coating were performed by gas powder laser cladding with the use of a powerful continous C02-laser radiation and direct feed of gas-powdered jet into the zone of treatment. The beam power was P=2,5 kW and treatment speed was V=O,5 rn/ruin, powder consumption was within limit g=O.5-O,7 g/sec. Powder jet was fed at angle 45° with a surface. The treatment was performed by a focused beam scanning in the direction perpendicular to the test speciment movement direction (scanning frequency is 200-250 Hz, beam area 4x2 mm2). Cladding of friction surfaces was carried out with track overlap and spacing h=2 mm. After grinding the coat thickness was in the range ofO,3-O,5 mm.For investigation ofthe coating hardness influance the built-up welding was performed by three type of sell-fluxing Cr-B-NiSi powders with dispertion 50-70 pm. They were flP-HX13CP (35-41 HRC), flPHX15CP2 (46-50 HRC), HP-HX1ÔCP3 (58-62 HRC). The specimens ofvolume heat-hardening steel 45 were standarts for the comparison.Coating structure were described'. They consist in two structural component: gamma-hard solution oversaturated withalloying elements and evetectic gamina+Ni3B.For preventing cracks cladding was carried out with direct heating-up of specimens by the gas-burner.There were prepared three parties of specimens. In each one there were four with the idential coatings. Results were averaged within the each party. The shoe 10x8 mm2 with the standard bearing shell A020-1 was used as a counterbody. 0819420883/961$6.00 SP!E Vol. 2713 /301 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/19/2015 Terms o...

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