Study On Process And Properties Of Laser Cladded Fe-based Wear Resistant Coatings On Inner Wall Of Barrel

As the demand for plastic products continues to increase,the development of injection molding machines is also accelerating.The injection molding machine barrel is one of the core components of the injection molding machine.During the service,long-term work will cause it to fail.Wear is one of the main failure modes of the barrel,which greatly reduces the working life of the barrel.As a new surface modification technology,laser cladding technology has been gradually applied to inner wall processing.Laser inner wall cladding technology is a branch of laser cladding technology,which is quite different from conventional laser cladding in terms of processing environment and scanning mode.At present,there are few studies on laser cladding on the inner wall of the barrel at home and abroad.Therefore,this paper systematically studies the laser cladding process of the inner wall of 40 Cr barrel to prepare an iron-based wearresistant coating with no defects,good shape,high hardness and high wear resistance,which provides technology and basis for laser cladding of the inner wall of the barrel.In this paper,the basic technology of laser cladding on the inner wall of the barrel is studied firstly,and the optimal process parameters are obtained.On this basis,the unique process of laser inner wall cladding,scanning mode and deflection angle,was deeply studied.The influence of unique process on the forming quality of cladding layer is analyzed.The influence of the scanning mode on the tilting dendritic area on the top of the cladding layer was explained by simulation calculation.OM,EDS and SEM were used to analyze the changes of cladding morphology,the change of lap area and the distribution of elemental elements under different bonding strategies,which provided a reference for large-area cladding.The wear resistance of the heat treatment substrate,the flat cladding layer and the inner wall cladding layer under normal temperature and high temperature conditions were compared and the wear mechanism was analyzed.Finally,the barrel simulation was physically cladded and analyzed.The research results show that the laser inner wall cladding process has a significant effect on the forming quality of the inner cladding layer.In different scanning modes,the cross-sectional area of the cladding layer in the radial spiral scanning mode is larger than that in the axial scanning mode.At the same time,the tilting dendritic area ratio of the radial spiral scanning mode cladding layer is smaller than the axial scanning mode.The change of the deflection angle has no obvious effect on the radial spiral scanning mode,but the larger the deflection angle is in the axial scanning mode,the more the cladding layer shape is toward the half teardrop shape,and the overall area is gradually reduced.The single-layer multi-pass and multi-layer multi-pass bonding strategies are systematically studied.The results show that the single-layer and multi-layer cladding layers obtained by two kinds of overlapping strategies of radial spiral scanning and axial scanning have better forming quality.At the same time,the overall size of the cladding layer in the radial spiral mode is relatively large.The remaining composite lap strategy and the filling lap strategy result in poor quality of the cladding layer.The analysis of the wear performance of the cladding layer at normal temperature and high temperature can be concluded that the wear resistance of the flat cladding layer increases by 6.7 times and the inner wall cladding layer increases by 5.3 times,which compared with the 40 Cr substrate after heat treatment(870 °C quenching,300 °C tempering).At high temperatures,the wear resistance of the flat cladding layer increases by 4.7 times,and the inner cladding layer increases by 3.8 times.It can be obtained that the inner wall cladding layer is slightly lower than the flat cladding layer,but higher than the conventional heat treatment matrix to meet the barrel requirements.The laser cladding application test was carried out on the inner wall of the 40 Cr barrel simulation part,and the inner cladding layer of the simulated part after laser cladding was tested.The results show that the cladding layer has good forming quality and the average surface hardness is 57.85 HRC,which can meet the requirements.In this paper,the related research on the preparation of Fe-based wear-resistant coating by laser cladding on the inner wall of the barrel is carried out.The laser process parameters optimization,the change of scanning mode,the change of deflection angle,the selection of lap strategy and the analysis of friction and wear mechanism are carried out,and the application test of the barrel simulation parts is carried out,this study provides a reference for the cladding of the inner wall cladding high-hard wear-resistant coating.