Rapid Identification of Calcium Aluminate Inclusions in Steels Using Cathodoluminescence Analysis
We propose a method to identify calcium aluminate inclusions in calcium-treated aluminum-killed steels (Ca12Al14O33, CaAl4O7, CaAl12O19, and Al2O3) using cathodoluminescence (CL) analysis. Such inclusions result in nozzle clogging and melting of the stopper rod during continuous casting. We obtain CL images and CL spectra of calcium aluminate inclusions in model samples of calcium-treated aluminum-killed steel. The model samples are prepared by heating mixtures of Fe powder, Al powder, and Ca shot at 1550 °C in an argon atmosphere. On the basis of the CL colors and CL spectra of the calcium aluminate inclusions, we demonstrate that it is possible to distinguish Ca12Al14O33, CaAl4O7, CaAl12O19, and Al2O3 inclusions from CaAl2O4 and Ca3Al10O18 inclusions, which do not cause nozzle clogging and melting of the stopper rod, by comparing CL images obtained using digital cameras with and without a built-in filter. The acquisition times for the CL images are less than 10 seconds. Thus, the method we present here can be applied for the rapid detection of harmful calcium aluminate inclusions during continuous casting. The CL spectra also provide basic information to specify compositions in agglomerated calcium aluminate inclusions.
This work was supported by JSPS KAKENHI [Grant Number 17H03435].
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