Technical Study On Q345 Steel Rust By Pulsed Laser Cleaning

Engineering machinery and equipment have been in harsh working environment for a long time,and the rust oxide on the surface seriously affects the service life and safety coefficient of parts.Therefore,it is crucial to effectively remove the oxide layer on the surface of materials for the maintenance of machinery and equipment.Traditional derusting technology include mechanical grinding,shot blasting,chemical cleaning and high-pressure water jet cleaning,etc.,but there are problems such as large damage to the matrix,serious pollution and inconvenient operation,which do not conform to the development trend of green cleaning.As a new cleaning method,laser cleaning technology has been gradually applied in many fields,such as engineering machinery,aerospace,protection of cultural relics and tire mold,etc.with its advantages of environmental protection,non-contact cleaning,easy operation and wide application range.In this paper,a laser cleaning study was carried out on the surface of rust oxide on Q345 steel commonly used in engineering machinery.Firstly,a layered cleaning model of oxide was established by analyzing the physical and chemical properties of attachments.Secondly,based on the layered model,the laser energy transfer process and cleaning mechanism were analyzed,and with the help of Comsol Multiphysics software,the single removal quantity prediction model of oxide was established.Finally,by exploring the influence law of different parameters on the surface properties of materials and cleaning efficiency,the cleaning process parameters were optimized to provide theoretical guidance and technical parameters for the application of laser cleaning technology in the industrial field.1.This paper analyzed the parameters of pulsed laser and the basic properties of dirt.Firstly,the optical characteristics of the pulsed laser were analyzed,including the quality of the output beam,the absorption effect of the laser and so on.Based on different cleaning paths and beam distribution,the contour model of the cleaning groove was established to guide the actual cleaning process.By scanning electron microscopy(SEM),energy spectrum analyzer(EDS)and X-ray diffraction(XRD)analysis of the rust material,surface morphology,chemical composition and element content of oxide were abtained.Layer structure were that:Fe2O3,Fe3O4 and Fe matrix,and integral sphere reflection method was used to measure the laser absorption rate of the materials in each layer,which were:58.6%.,53.8%and 35.0%,respectively.2.Based on the layered cleaning model of oxides,the cleaning mechanism was analyzed and the prediction model of single removal quantity was established.Through the analysis of the properties of rust oxides,the layered cleaning model of oxides was established,and the laser energy transfer process and the main cleaning mechanism were analyzed.With the Comsol Multiphysics software,the influence of different laser parameters on the temperature field distribution of each layer of materials was analyzed qualitatively.Meanwhile,the central composite test was designed to obtain the single removal quantity prediction model H1 and H2 for Fe2O3 and Fe3O4 regarding the laser peak power density and scanning velocity and a prediction model H3 for removing Fe2O3 and Fe3O4 at the same time was derived.Combined with experimental verification,it was proved that the mechanism of laser cleaning were mainly ablative removal mechanism and thermal stress removal mechanism,and the single removal quantity prediction model was effective.3.The key surface properties(surface roughness,microhardness,corrosion resistance,etc.)and cleaning efficiency of engineering machinery materials were optimized.Taking the laser power,repetition frequency(pulse width)and spot overlapping rate as variables and comprehensively considering the influence of each parameter on the performance and cleaning efficiency,the optimal process parameters were obtained as follows:laser power was 280W,repetition frequency was 10kHz(pulse width was 84ns)and spot overlapping rate was 70%.Based on the optimal process parameters,the oxygen content on the surface of the material was the lowest,the cleaning efficiency was the best,and the surface roughness was low.Compared with the original sample,microhardness increased by 60%and corrosion resistance increased by 62.9%.