Research On The Forming Processes And Properties Of 316L Stainless Steel Manufactured By Plasma/Laser Directed Energy Deposition

Directed energy deposition with high deposition efficiency is an important part and one of the main development directions of metal additive manufacturing.In this paper.the directed energy deposition additive manufacturing of 316 L stainless steel was studied by plasma directed energy deposition and laser directed energy deposition..The process characteristics and properties of energy deposition processes were studied.The main research contents and results are as follows:(1)The effect of laser directed energy deposition on the size of the melt path was studied.The effects of laser power,scanning speed,and powder feeding speed on single-pass forming were revealed.Remarkable and reliable layer width and layer height regression equations were determined by response surface method,and the interactive influence of process parameters on melt path was studied.The powder feed speed determines the change interval of the melt path size.As the powder feed speed decreases,the influence of the laser power and scanning speed on the width of the melt path increase.(2)The neural network model of parameters and size prediction was built by MATLAB.Compared with the regression equation,the BP neural network model has higher prediction accuracy.The reverse prediction model was built to predict the process parameters by design size,but the inspection accuracy was poor.The process parameters’ prediction accuracy was improved by combining the forward and reverse prediction,and the process prediction error rate was reduced to less than 10%,so as to realize the rapid establishment of process database.(3)The average powder utilization rate of laser directed energy deposition was 36.3%,while the average powder utilization rate of plasma directed energy deposition reached 73.1%.The density of the samples of the both two heat sources reached more than 98%.Through the mechanical property test,it was found that the mechanical properties of the two processes have reached the level of forgings,and there was obvious anisotropy.The tensile property of the specimen in the vertical deposition direction was the best.The change rule of microhardness is uniform.In the vertical direction,the hardness change trend is that both ends were high and the middle was low;in the horizontal direction,the change trend is low ends and the middle is high.