Study On Microstructure And Properties Of Valve Core Parts Remanufactured By Laser Cladding

Fluid control equipment is an important part of China's equipment manufacturing industry.As its core product,valve equipment is a mechanical device to control medium circulation or cut off.It is widely used in petroleum,chemical and natural gas fields,and is one of the commonly used general machinery in the national economy.For example,flat gate valve,the key component of Christmas tree,is subject to high pressure,wear,corrosion and other effects in the process of use,which is prone to wear and erosion corrosion,seriously affecting its service life and performance.There is a huge stock of valve equipment in China,and a large number of valves are scrapped due to the failure of core valve parts every year.If effective remanufacturing measures can be taken to repair the failed or retired valve equipment,it will produce great social and economic value.Therefore,under the support of the National Natural Science Foundation of China "service life prediction method and experimental research of additive remanufacturing mechanical parts(51505268)",the laser cladding remanufacturing research on the core part of flat gate valve is carried outFirstly,the laser cladding remanufacturing process optimization of 40 Cr steel was studied.Taking scanning speed,laser power,powder feeding speed and defocusing amount as independent variables,dilution ratio and microhardness as objective functions,the multiple regression equation of laser cladding process parameters was established by uniform design method,and the optimal process parameters of single pass cladding were obtained.The influence of overlap ratio on the surface cladding quality of multi-pass cladding layer was studied,and the optimal overlap ratio of multi-pass cladding layer was obtained.Then,the laser cladding remanufactured coating was prepared based on the optimal process parameters of single pass cladding,and the microstructure and properties of the remanufactured coating were studied.The influence of laser power and scanning speed on the microstructure of the remanufactured coating was analyzed.The microhardness distribution of the cladding layer under the optimal process parameters was studied.The friction and wear properties of the cladding layer were studied by friction and wear tests.Finally,taking the real flat gate valve core as the research object,the laser cladding remanufacturing of valve core parts was carried out.The damaged state of the valve core parts is analyzed,the area to be repaired is determined and a three-dimensional model is established.The valve core parts are remanufactured and repaired by three different process paths,and the restored valve core parts are processed by CNC machine tools.