Investigation on fretting Wear performance of laser cladding WC/Co06 coating on 42CrMo steel for hydraulic damper

Hydraulic dampers are widely used in nuclear power plant pipelines and mechanical equipment as a kind of vibration reduction and energy consumption protection device. The connection part of the pin head (42CrMo steel) is prone to fretting wear. In this paper, the purpose is to prepare composite coatings for improving the wear resistance of pin heads by laser cladding. The micromorphology, phase, hardness and micro-friction wear properties of different WC content (5 wt%, 10 wt%, 15 wt%, 20 wt%) were fully studied. The results show that the elements W, C and Cr are distributed on the white network structure of the cladding layer and play a role in solid solution strengthening; the Co06 cladding coating mainly contains intermetallic compounds such as γ-Co solid solution and Cr23C6. New phases such as WC, Fe3W3C, CoCx, Cr7C3 are formed in the coating, and these new phases play an important role in improving the performance of the cladding layer; The hardness of the coating reaches the highest 810HV0.3 and the lowest is 425HV0.3, which is significantly higher than that of the matrix; The friction coefficient of the coating is significantly lower than that of the matrix, and the wear volume of the cladding layer is also greatly reduced. When the WC content is 15%, the minimum wear volume is 50.7% lower than that of the matrix; The wear mechanism of the matrix is changed from abrasive wear, spalling wear and oxidative wear for oxidative wear and adhesive wear. Taking into account comprehensively, this paper believes that the coating with WC content of 15 wt% has the best wear resistance. In this paper, laser cladding technology was used to prepare WC/Co06 coating on the surface of 42CrMo steel for large hydraulic damper piston rod. The phase of the cladding layer was analyzed by X-ray diffractometer (XRD); the cross-section of the cladding layer was measured by a 402MVD Vickers microhardness tester with a load of 300 g and a loading time of 15 s, and the test point started from the top of the cladding layer cross-section, 10 points are measured along the depth direction, and the distance between the test points is 100 μm.A tangential fretting wear tester (RTEC MFT-50, USA) was used to conduct the fretting wear test. The test environment was room temperature, no lubrication, and the abrasive parts were GCr15 steel balls (diameter 9.525 mm, hardness 690 HV, rough surface) degree Ra = 0.025 mm). After the test, the wear morphology was observed by scanning electron m