Along with the continuous development of social economy, energy saving and emission reduction, greenhouse gas emission control and air pollution prevention and control have become the issues that need to be emphasized nowadays. Hydropower, as a new energy source of pollution-free and non-polluting power generation, has made great contributions to the power industry.
The main form of failure of hydropower overcurrent components is cavitation, which can produce fish scale pits or spongy surface on the surface of hydraulic turbine overcurrent components, destroying the original winding conditions on the surface. When serious, it will affect the safe operation of hydraulic turbine, especially the runner and blades.
For cavitation, the common traditional repair and strengthening methods are mainly manual surfacing welding, flame spraying tungsten carbide coating and manual application of epoxy coating. Such methods have problems such as high labor intensity, serious pollution such as on-site dust, noise, etc. The coating is physically bonded with the substrate, limited bonding strength, shedding beyond the strength limit and limited period, large heat-affected zone, and large deformation.
ZG06Cr13Ni5Mo material and cobalt-based corrosion and wear-resistant alloy material laser clad on the surface of ZG06Cr13Ni5Mo were processed to a uniform standard specimen, in which the cladding specimen retained a thickness of 0.5mm of the cladding layer, and tested according to the same test conditions. The ultrasonic accelerated cavitation testing machine is used to carry out the comparative cavitation test, observe the appearance and shape, weigh the test, and calculate the amount of cavitation. The test equipment model YPS17B-HB, ultrasonic frequency 20KHZ, amplitude 90 ± 10μm, water temperature is room temperature, test time 0-20h.
From the appearance and morphology of the comparison specimens, it can be seen that after 20h accelerated cavitation test, the surface layer of the substrate specimen showed honeycomb cavitation holes, while the laser cladding specimen did not see the phenomenon of bright cavitation. After 20 hours of accelerated cavitation test, no obvious quality loss was detected in the laser clad specimens.
