Properties of 316L stainless steel lattice structures prepared by selective laser melting
Aiming at the problems of unstable compression process and insufficient mechanical properties of truss structure,a kind of honeycomb truss structure was designed based on board honeycomb structure.Three different parameters of aspect ratio of 1.5,1.0 and 0.5 were designed by adjusting the height of the structure,and 316L stain-less steel was used to prepare the structure by selective laser melting(SLM).The internal structure of the sample was analyzed by optical microscope and electron microscope.It was found that the sample had small grain size and few internal defects,no macroscopic defects were found,and the overall molding quality was good.The mechanical properties of the structure were also studied by theoretical,experimental and simulated means.The results show that the yield strength of the upgraded structural samples with different aspect ratios is 256,142,106 MPa,respec-tively,which is 524%,306%and 279%higher than that of the original structure,and the performance of the sample with aspect ratio of 0.5 is the best.The yield strength of the upgraded sample with the same relative density is increased by 159%compared with the original structure.With the decrease of the aspect ratio,the compression process of the sample becomes more stable,and the stress-strain curve tends to be flat in the yield stage.ABAQUS software was used to simulate the quasi-static compression of the designed structure.The simulation results show that the simulated quasi-static compression process of the structure with aspect ratio of 1.5 is unstable,and some members appear to be disturbed.With the decrease of the aspect ratio,the whole process is gradually stabilized and the yield strength of samples is increased.The finite element analysis results agree with the experimental results,and it proves that aspect ratio adjustment of the structure can improve the compression stability of the member.The design method of this truss structure can be applied to the design of other lattice structures,at the same time,the structure can be used as the basic unit of lattice structures and the supporting unit of additive manufacturing,which can provide ideas for improving the mechanical properties of 316L stainless steel samples of lattice structures.
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