Characterisation of Inclusions in Clean Steels via Laser Ablation-ICP Mass Spectrometry

Abstract

A new method for detection and assessment of inclusions in clean steels based on laser ablation and ICP mass spectrometry has been developed. Samples were subjected to UV laser ablation (Nd Yag) and ion intensities of elements of interest were monitored on a time-resolved basis. Lasers exhibiting both gaussian and flat-top intensity beam distributions were used. Analytical response for inclusion and matrix elements as a function of laser ablation parameters was studied and procedures were developed for rapid inclusion characterisation and elemental mapping. Main inclusion types identified in clean steels were Mn-S, Mg-Al and Mg-Al-Ca-Ti-Si. Results indicate the considerable analytical potential for the laser ablation technique in a production environment.KEY WORDS: clean steels; inclusions; mapping laser ablation; ICP mass spectrometry.a versatile microanalytical technique and is analogous to the SSE method in that elemental analysis is based on direct spectral observation of the plasma discharge. LIBS has yet to be fully exploited for characterisation of inclusions in clean steels but the potential is considerable given its success as a microanalytical tool [8][9][10][11] for spatially resolved measurement and depth profiling. 10,[12][13][14] Progress in the use of LIBS for inclusion measurement has recently been elaborated by Noll et al. 15) and Laserna et al. 16)Laser ablation in combination with ICP emission or ICP mass spectrometry constitutes an important bulk and microanalysis tool as evidenced by an extensive literature. [17][18][19] Relative to the LIBS approach a major advantage of the laser-ICP combination is the improved measurement sensitivity particularly for ICP-MS detection where the current state of the art is at the ng/g level. The high detection sensitivity combined with good spatial measurement capability has been exploited in geological investigations including the characterisation of fluid inclusions [20][21][22] and for zonation studies in minerals. [23][24][25] The aim of this research was to evaluate the potential of the LA-ICP-MS method for steel cleanness assessment. The effects of key parameters, i.e. laser energy, frequency, spot size, and rate of sample translation on signal response have been investigated using both gaussian and flat top beam intensity distribution profiles. The approach permits rapid identification of elements present in inclusions and gives new information related to the spatial distribution of inclusions in samples. Experimental MaterialsA glass standard reference material (SRM 612, NIST, Gaithersburg, MD) was used for initial instrument set-up (daily basis) and in-house research materials previously characterised by optical metallography were used in method development. InstrumentationLaser ablation was performed using Nd Yag lasers (LSX-100 and LSX-200, frequency quadrupoled; CETAC Technologies, Omaha) interfaced to an ICP mass spectrometer (Agilent Technologies, HP 4500). The main difference in the two laser systems was that the LSX-100 exhibits a gaussian ...

Application of Laser Ablation ICP Mass Spectrometry for Analysis of Oxide Particles on Cross Section of Alloys and Steels

“…The relationships between the minimum size, dV,min, for some pure oxide inclusions, which might be distinguished by LA-ICP-MS analysis of metal samples, and the content of soluble M (M = Si, Mn, Ti, Al, Mg and Ca) element can be calculated from Eqs. (10), (11) and (12) by using the parameters given in Table 3. The results are shown in Fig.…”

“…In recent years, the LA-ICP-MS was applied for the direct analysis of steels and alloys concerning to the determination of the bulk composition, [5][6][7][8] the content of soluble and insoluble elements 7,8) the spatial and surface distribution of elements in steels and alloys, 8,9) and the mapping analysis of inclusions. [10][11][12][13][14] In this study, the LA-ICP-MS method is applied for the estimation of oxide particles containing Al2O3, MgO and other oxides on the cross section of Fe-10 mass% Ni alloy. Some limit factors for the analysis of particles by the LA-ICP-MS are discussed regarding to the content of soluble elements and the number of inclusions in metal.…”

Original Position Statistic Distribution Analysis of Trace Element Segregation in Nickel-base Super Alloy by LA-ICP-MS

“…Based on spark spectrometry and LA-ICP-MS, Prof. H. Z. Wang and their group 8,9) have developed the original position statistic distribution analysis techniques for rapid inclusion characterisation and elemental mapping in the large area from millimeter to centimeter scale. C. Dubuisson and their group 10) have established the method for detection and assessment of inclusions such as Mn-S, Mg-Al and Mg-Al-Ca-Ti-Si in clean steels by LA-ICP-MS, and the results showed considerable analytical potential ability. C. Latkoczy 11) compared the quantitative element mapping of Mg alloys by LA-ICP-MS to that of EPMA and good agreement was achieved .…”

Resolución espacial en la ablación láser acoplada a la espectrometría de masas con fuente de plasma de acoplamiento inductivo.

“…Concretamente, en el campo de los materiales metálicos se han realizado diversos estudios, tanto para identificar inclusiones o heterogeneidades, como capas de recubrimiento. En relación a la resolución lateral, Dubuisson et al [9] han evaluado el potencial de la técnica para establecer la homogeneidad de los denominados "aceros limpios", identificando inclusiones del tipo: Mn-S, Mg-Al y Mg-Al-Ca-Ti-Si. Nafisi et al [10] presentan un méto-do de barrido lineal que permite controlar las segregaciones de partículas de ·-Al formadas durante la solidificación de aleaciones de Al-Si, mostrando que mediante calibración externa e integrando zonas de 1-5 µm, se pueden identificar segregaciones en la escala 6-7 µm con errores <25 % .…”