Characterization Of Hardness And Tensile Strength Of 3D Printed Parts Based On Laser-induced Breakdown Spectroscopy

The mechanical properties of metal 3D printing parts directly affect the safety and life of the parts,so it is necessary to test the mechanical properties of the parts.However,the traditional destructive mechanical properties testing experiments are often not applicable to the one-time forming metal 3D printing parts.Therefore,the nondestructive testing of the mechanical properties of metal 3D printing parts has important research and application significance.Laser-induced breakdown spectroscopy(LIBS)is an atomic emission spectroscopy technology,which has many advantages,such as no sample pretreatment,on-line,fast,and almost non-destructive.he LIBS technology has an obvious matrix effect,which makes the spectral characteristics of laser-induced plasma reflect the physical and chemical characteristics of the analyzed object.This paper attempts to study the feasibility of using LIBS technology as a method for characterizing the mechanical properties of metal 3D printing parts.In order to explore the feasibility of LIBS technology to characterize the mechanical properties of metal 3D printing parts,two important mechanical properties,hardness and tensile strength,were studied in this paper.Samples with different hardness and tensile strength were prepared by selective laser melting technology,and the plasma spectrum data of the samples were collected by LIBS technology.Firstly,the plasma spectral characteristics and plasma physical properties of18Ni300 die steel samples with different surface hardness were studied.The positive correlation between the intensity ratio of ion and atomic lines and hardness were established.The positive correlation between plasma temperature and hardness were established.The theoretical explanation of the positive correlation was given from laser shock wave velocity and laser ablation rate.Secondly,the plasma spectral characteristics of 18Ni300 die steel samples with different tensile strength were analyzed.The PCA analysis method was introduced to distinguish the samples with different tensile strength.The selected spectral data at300-340 nm,370-410 nm and 460-500 nm were able to distinguish the samples with different tensile strength significantly.By analyzing the spectral line characteristics of samples with different tensile strengths,a positive correlation between the intensity ratio of the atomic lines of the alloy elements and the matrix elements of the sample and the tensile strength were established.Finally,the defect degree of the sample was studied by LIBS technology.The samples were analyzed by LIBS surface scanning,and the defect distribution was analyzed by drawing the two-dimensional intensity distribution map of characteristic spectral lines.The deviation from normal coefficient ? was introduced to quantitatively evaluate the defect degree of the samples.The research results provide a theoretical basis for LIBS to characterize the hardness and tensile strength of metal 3D printing parts,prove the feasibility of LIBS as a means of testing the mechanical properties of metal 3D printing parts,and expand the application scope of LIBS technology in the field of testing.