Huang Wei Shanghai Baosteel Equipment Maintenance Co., Ltd. In March 2010, Nanjing Meigang's centrifugal air compressor increased vibration during operation. After the parking, the maintenance personnel found that foreign matter entered the rotating impeller and collided with the impeller at high speed, which caused the blade of the entire impeller to be damaged, and the impeller dynamic balance was destroyed, so that the unit could not continue to operate. The design flow rate of the centrifugal air compressor is 60; 1; the medium is air, the rotational speed is 495, the rotor material is 14 stainless steel, the working temperature is 200.0, and the impeller is the third-stage impeller. Due to the high speed of the air compressor, the conventional repairing methods have the defects of high cycle length and high material performance. Through research, the author intends to use laser cladding surfacing to repair.
1 Laser cladding technology Laser cladding technology uses laser as a welding heat source. The seed surface engineering technology for forming a molten metallurgical joint between the substrate surface and the surfacing material can greatly improve the mechanical properties of the surface hardness, wear resistance, corrosion resistance and fatigue resistance, thereby improving the service life of the material.
Select the laser cladding powder with very similar material composition, and the composition of the village material 1. Use the laser casting method to build the test sample. , each test sample is produced according to national standards.
From the metallographic organization, 1 winter 1 river was found to be dense and flawless, and the welding consumables were well bonded to the substrate and the heat affected zone was very small.
The hardness test was performed using 000 people, and the hardness of the base and the laser cladding area was compared. It can be seen that the hardness of the heat affected zone of the laser cladding portion is substantially the same as that of the substrate.
Tensile performance test was carried out using 35,305, and 3 is the tensile performance comparison between the substrate and the laser cladding region. It can be seen that the properties of the cladding area and the substrate are basically the same after stretching, and the more important laser filling technology is the traditional welding technology. The superiority of the 1 method. Since the laser does not have a rapid heat of approximately adiabatic melting, it melts over 1 and has a very fast cooling overfill. Similar to fast, quenching. It is possible to refine the grain structure and to distribute the distribution of the chelating components, so that the weld overlay has excellent performance. In addition, the input of the laser can be optimized by the art optimization. The dilution of the matrix material can be reduced to a lower extent.
2 Construction process The ideal state of impeller repair is that the performance of the repair part can approach or exceed the surface of the impeller before repair. Under the research, if the appropriate technology and cladding shoes are selected, the centrifugal air compressor can be satisfied. Conditions such as speed and temperature.
Construction 1 art process 4 is small.
The laser melting art parameters are determined and the specific construction process of the melting process is 3 inspection and washing. The eight blades of the impeller outlet are different. The maximum defect surface length is about 3, and the blade thickness is 2. The workpiece surface is cleaned and derusted, and the outer dimensions are measured and nondestructive testing is performed.
Prototype line measurement. A relatively complete impeller profile is selected and compared to the profiled sample taken on the new rotor and the measured raw data to confirm the impeller profile.
The demand is higher. After analysis and comparison, the high-strength stainless steel metal powder is used as the powder for laser cladding gold. Compared with the impeller raw materials, the alloy powder not only has the characteristics of self-deoxidation and slagging, but also has excellent corrosion resistance and wear resistance, and has mechanical properties satisfying the requirements of the workpiece after the cladding. 4 Resident village materials have good junction strength and ideal metallographic organization.
6 process parameters. According to the determined laser cladding metal powder for the size of the impeller to be processed, the cladding process parameters are formulated. Each layer has a cladding thickness of 06, a scanning speed of 12, and is melted to the required size with sufficient machining allowance.
1 machining. Compare the drawn impeller type line template.
Grinding the impeller surface to ensure that the shape of the impeller is restored to its original design size. In this process, it is also necessary to perform multiple coloring flaw detection, and the cracks found in the process are processed into the chamber and the crucible is coated. The finished impeller is finally refined to ensure dimensional accuracy after repair.
The geometrical dimensional tolerance and non-destructive flaw detection are performed. The impeller surface is polished after the inspection of the whistle is completed.
Low speed dynamic balance. The low-speed dynamic balance test is carried out to ensure that the impeller has a new calibration accuracy of 025. After the test, pay attention to the lubrication of the parts. Prevent the wear of the rotating friction parts and affect the accuracy of the dynamic balance test.
3 Application effect This time, the laser cladding is used to repair the impeller. Only 2 places are saved for the user. The overall replacement cost of the impeller is more than 1.2 million yuan. The design requirements of the impeller and the new rotor repaired by laser cladding technology are almost the same, and the equipment is improved. Work efficiency, successful trials after installation on site, and have been running well so far.
4 Conclusion Through the tracking analysis of the repaired impeller, it is found that the impeller after laser cladding has similar performance to the original impeller material, which can meet the needs of production conditions. At the same time, the use of laser cladding technology to repair the impeller is not much less expensive than manufacturing new products. Moreover, it has overcome the difficulty of supplying spare parts and can bring very significant economic and social benefits.
I Qian Miaogen. Material surface technology and its application manual elbow. Beijing Machinery Industry Press. 1998656
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