Study on Microstructure and Properties of Multi-layer Multi-pass Laser Wire-Filled Cladding Layer on Surface of Q345B Steel
Multi-layer multi-pass laser wire-filling cladding of Q345B mild steel plate with a thickness of 20 mm was carried out by cross orthogonal surfacing method,and the macroscopic morphology,microstructure,phase composition,microhardness and corrosion resistance of the cladding layer were investigated.The results show that the macroscopic shape of the cladded layer obtained by multi-layer multi-channel laser wire filling process is good,with no obvious defects such as porosity,cracks,etc.The cladding layer mainly consists of cladded zone,overlapped zone,phase transition affected zone,fusion zone and heat affected zone.The microstructure of the base matal is mainly ferrite and pearlite,and the microstructure of the cladded layer is mainly ferrite,Widmanstatten structure and martensite.The hardness of the cladded layer overall shows a gradient distribution,which is mainly caused by the influence of the microstructure and the size of the grains,and the average hardness of the cladded layer is 320.13 HV,which is higher than that of the base matal.In 3.5%NaCl solution,the polarization curve of the cladded layer has a blunted region,and its corrosion resistance is better than that of the base metal.The multi-layer and multi-pass laser wire-filling cladding process can meet the preparation requirements of the actual engineering for the cladding layer.
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