Research On Fabrication Characteristics Of Stainless Steel And Low-carbon Steel By Double Wire-feed And Plasma Arc Additive Manufacturing

Plasma arc additive manufacturing technology takes plasma arc as heat source,stainless steel and low carbon steel wire as adding material,and forms the complex geometric components with full density and excellent performance.It has the advantages of high molding precision,low production cost and short manufacturing cycle.This paper mainly studies the robot-plasma arc additive manufacturing technology,using double wire-feed process.Taking stainless steel + stainless steel,low carbon steel + low carbon steel,stainless steel + low carbon steel as the research object,the deposition rate,appearance morphology and size,microstructure and composition,mechanical properties and other aspects of the material manufacturing were studied in depth.Firstly,ER308L stainless steel was taken as the wire object.The deposition speed was used as a variable parameter to study the characteristics of the stainless steel components added by the double wire-feed and plasma arc additive manufacturing(DWF-PAM)process.The deposition rate test shows that the deposition rate of the DWF-PAM process is 2.06 times that of the single wire-feed and plasma arc additive manufacturing(SWF-PAM)process.The tensile strength of the DWF-PAM process sample is increased by 53.0MPa,higher by 10,2%and the elongation increases by 106%.Optical microscopy showed that there were a large number of equiaxed ferrites in the equiaxed zone of the DWF-PAM process samples,while the area of the SWF-PAM process samples was non-equiaxed ferrites.The results of the measurement of the grain diameter indicate that the grain size of the DWF-PAM process samples is finer and the grain size is negatively correlated with the speed of the deposition.Then,the ER50-6 low-carbon steel wire was taken as the research object,and the SWF-PAM and DWF-PAM process experiments were carried out.Under the same process parameters,the DWF-PAM process significantly increased the deposition rate of low-carbon steel,reaching 1.98 times the SWF-PAM process.Mechanical tests show that,compared with the SWF-PAM process,the tensile strength of the DWF-PAM process sample is increased by 44.5MPa on average,and the elongation is basically the same.At the same time,it was found that the DWF-PAM process can significantly increase the micro hardness of the deposition when the deposition speed is higher than 30cm/min,up to 17.5HV.The microstructure observation showed that the DWF-PAM technology obtained finer grain ferrite and more pearlite.The measurement of grain size showed that the ferrite grain of the DWF-PAM sample was finer.Both process grain sizes are negatively correlated with the deposition speed.Finally,two types of stainless steel + low-carbon steel heterogeneous wire were used to study the preparation of new high-performance steel by plasma arc additive manufacturing process.Five groups of stainless steels and low-carbon steels with different mass fractions were selected.Among them,the tensile strengths of the samples according to the mass fraction of 5:5,6:4 and 7:3,respectively,were respectively over 1000MPa,up to 1072.3MPa Micro Vickers hardness were over 300HV,up to 354.5HV.Microstructure and XRD phase composition test found that the ratio of 5:5,6:4 and 7:3 samples were found in the presence of a large number of lath martensitic tissue.EDS analysis results show that the Cr,Ni and other elements are uniformly distributed in the sample group,with no apparent segregation of elements.The content of Cr in the five composite materials exceeds 12%.