Evaluation of stress on metal surfaces by laser-induced breakdown spectroscopy

Abstract

In this study, we evaluated the feasibility of using laser-induced breakdown spectroscopy (LIBS) to determine the stress generated in metal materials by comparing measured stress levels with those determined by x-ray diffraction (XRD). Magnesium (Mg) alloy specimens underwent impact stress generated under ultrasonic peening. Stainless steel specimens were subjected to bending stress. The reference stress for each specimen was measured using XRD. LIBS measurements were performed to determine the correlation between stress distribution and the ratio of ionic to atomic spectral line intensity. The stress distribution from the surface to the interior of the ultrasonic-peened specimens measured by LIBS showed a similar tendency to that measured by XRD, but there was a difference in the maximum measurable depth. Additionally, the tensile and compressive stress distributions measured by LIBS on bending specimens showed similar trends to those of XRD. From these results, it was possible to measure the correlation between the stress state of the metal matrix and the spectral line strength of LIBS, thus confirming the potential for stress measurement using LIBS.

A Spectral Optimization Method To Enhance Handheld LIBS For T91 Aging Grade Classification Using Lorentzian Profile And Kalman Filter

“…Rusak et al 10 investigated the change in the Ca/F signal ratio at different depths of the archaeological bones, and found that the signal ratio could be used to distinguish the degree of preservation of the bones. Kang et al 11 analyzed the stress distribution in metals using the ratio of ionic to atomic spectral line intensity and confirmed the potential of using LIBS to measure stress in metals.…”

“…However, for the actual spectral data value 𝑦 𝑐−1 is not equal to 𝑦 𝑐+1 in most cases, it is difficult for 𝑦 𝑐−1 and 𝑦 𝑐+1 to satisfy the ideal fitting profile distribution when 𝑥 𝑐 is constant. For this reason, by taking (𝑥 𝑐−1 , 𝑦 𝑐−1 ) and (𝑥 𝑐+1 , 𝑦 𝑐+1 ) into Equation (11) respectively with 𝑥 𝑐 as the central wavelength of the spectral line, there will be two Lorentzian fitting profile with peak areas noted as 𝐴 1 and 𝐴 2 . Then the average area 𝐴 0 of 𝐴 1 and 𝐴 2 can be taken as the area of the ideal Lorentzian fitting, which can make the closest match to 𝑦 𝑐−1 and 𝑦 𝑐+1 .…”

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

“…An interesting application was proposed by Kang et al who discussed the use of LIBS for the evaluation of stress on the surfaces of a magnesium alloy and a steel plate . 46 Stress was induced to the magnesium alloy by ultrasonic peening, whereas bending was used to stress the steel plate. The ion to atom line intensity ratios were used as the basis of the analysis, with Mg being the analyte in the magnesium alloy and Cr being used for the steel sample.…”

Analysis of Changes in Spectral Signal According to Gas Flow Rate in Laser-Induced Breakdown Spectroscopy

“…Plasma generated through laser ablation of the material surface may include, not only chemical information of the material, but also physical information of the material surface. For example, the possibility of analyzing the physical properties of the surface of the material has been reported based on the characteristic that the spectral signal of plasma appears different depending on the stress, hardness, and roughness of the material [9][10][11][12].…”