Laser ablation breakdown spectroscopy technique for simultaneous analysis of steel and slags in metallurgical samples

• The original purpose of this research was to develop a method for fast, simultaneous analysis of both the steel and slag content of heterogeneous metallurgical samples for process control. The method is based on Laser Induced Breakdown Spectroscopy (LIBS). The reason for choosing LIBS is that it can be employed for both conductive and non-conductive materials, and is relatively insensitive to sample shape and surface finish. The heterogeneous samples produced contain large numbers of sub-millimetre slag particles that cannot be completely separated from the surrounding steel in a LIBS analysis. A method has therefore been developed to perform a line scan analysis with approximately 0.5 mm resolution and 10 mm length along the sample. The laser pulse rate is 20 Hz and the scan speed is 1 mm/s. Slag particles appear in the line scan as "polluted areas" of the steel with very high concentrations of e. g. Ca, Al and Si. A mathematical model was developed to evaluate the data in steps, based on a single calibration. Firstly, "clean steel" areas are identified and the steel composition determined. In the second step, the average composition across the entire length of the scan is determined. In the final step, the average slag composition is determined by means of a difference calculation. The method was tested on several samples from the development of the heterogeneous sampler. It was found that the elements C, Si, Mn, P, S and Al can be determined in the steel with an RSD of a few percent. In the slag, the RSD's are higher, around10% for several important elements. It is expected that the method can be further developed for rapid analysis of smaller non-metallic inclusions.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Nyckelord

Laser ablation

Optical emission

Steel analysis

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)