Methodology of steel cleanliness assessment

Burty, M.; Louis, Christine; Dunand, P.; Osmont, P.; Ruby-Meyer, Fabienne; Nadif, M.; Penet, F.; Isono, T.; Takeuchi, Ei-ichi; Toh, Tze Yan.

doi:10.1051/metal/200097060775

Cited by 14 publications

(18 citation statements)

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“…4) X-ray Detection 42) : An inclusion distribution can be constructed by dividing a sample into several wafers and subjecting each to conventional X-rays to print penetrameter radiograghs for image analysis. 5) Slime (Electrolysis) 28,39) : In this accurate but time consuming method, a relatively large (200 g-2 kg) steel sample is completely dissolved in acid (HCl) and the nonmetallic inclusions which remain are collected for inspection, counting and further analysis. Alternatively, in order to protect FeO inclusions, most of the dissolution can be accomplished by applying electric current through the steel sample immersed in a FeCl 2 or FeSO 4 solution.…”

Section: Inclusion Evaluation Of Solid Steel Volumesmentioning

confidence: 99%

“…12) Inclusions cause high-intensity spark peaks (relative to the background signal from the dissolved elements), which are counted to give the PDA index. 39) 6) Laser Microprobe Mass Spectrometry (LAMMS) 40) : Individual particles are irradiated by a pulsed laser beam, and the lowest laser intensity above a threshold value of ionization is selected for its characteristic spectrum patterns due to their chemical states. Peaks in LAMMS spectra are associated with elements, based on comparison with reference sample results.…”

Section: (B) Composition Is Measured With Electronmentioning

confidence: 99%

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State of the Art in Evaluation and Control of Steel Cleanliness.

2003

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This paper first reviews the current "state-of-the-art" in the evaluation of steel cleanliness, discussing over 20 different methods. The demand for cleaner steels requires lowering non-metallic oxide inclusions and also controlling their morphology, composition and size distribution. Because no single method can measure all of these aspects accurately, it is best to combine several methods together to quantify steel cleanliness in a given operation. Owing to the cost, time requirements, and sampling difficulties, steel cleanliness is widely inferred using total oxygen, nitrogen pick-up, and other indirect methods. Recent cleanliness values using these indicators are summarized for LCAK at many steel plants around the world. Secondly, this paper reviews operating practices to improve steel cleanliness at the ladle, tundish and continuous caster, emphasizing findings quantified with plant measurements. Inclusions come from many sources, including deoxidation, reoxidation, slag entrapment, refractory wear, and chemical reactions. They generate many defects such as cracks and slivers in the steel product. Steel cleanliness is controlled by attention to a wide range of important operating conditions throughout the steelmaking and casting processes. For ladle operations, FeO and MnO in the slag, ladle treatments, and inclusion modification are discussed. For tundish operations, tundish depth and capacity, casting transitions, refractory lining, tundish flux; gas stirring, and flow controls are discussed. Important transfer operations from ladle to tundish and from tundish to mold, such as argon protection, sealing issues, and SEN clogging are summarized. Caster operations reviewed include the effect of casting speed, fluid flow pattern control, surface level control, and caster curvature.

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Section: Inclusion Evaluation Of Solid Steel Volumesmentioning

confidence: 99%

Section: (B) Composition Is Measured With Electronmentioning

confidence: 99%

State of the Art in Evaluation and Control of Steel Cleanliness.

2003

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“…[47] Fig. 15-Typical exogenous inclusions in steel: (a) inclusions from lining refractory; [18] (b) exogenous inclusion in C-Mn large forging (200 ton [28] product samples, including metallograph microscope observation, [10,98,105,106] image analysis, [8,10,107] sulfur print, [108,109] scanning electron microscopy, [17,110] optical emission spectrometry with pulse discrimination analysis, [109,[111][112][113][114] laser microprobe mass spectrometry, [115] X-ray photoelectron spectroscopy, [110] Auger electron spectroscopy, [110] and cathodoluminescence microscope. [86] Several methods directly measure inclusions in the three-dimensional steel matrix.…”

Section: Methods To Detect Inclusionsmentioning

confidence: 99%

“…[86] Several methods directly measure inclusions in the three-dimensional steel matrix. Several of these scan through the sample with ultrasound or X-rays: conventional ultrasonic scanning, [12,13,116,117] Mannesmann inclusion detection by analysis surfboards [118] (also called liquid sampling hot rolling [5,109,119] ), scanning acoustic microscope, [120] X-ray detection, [101,[121][122][123][124] chemical dissolution, [17,68,100,125] slime (electrolysis), [100,108,114,126] electron beam melting, [127,128] cold crucible melting, [109] fractional thermal decomposition, [114] and magnetic particle inspection. [99,129,130] Several methods determine the threedimensional inclusion size distributions after the inclusions are extracted from the steel: Coulter counter analysis, [131] photoscattering method, [106,132] and laser-diffraction particle size analyzer.…”

Section: Methods To Detect Inclusionsmentioning

confidence: 99%

“…For example, Nippon Steel used total oxygen measurement and EB melting for small inclusions and the slime method and EB-EV for large inclusions. [114] BaoSteel employed total oxygen measurement, MMO, XPS, and SEM for small inclusions, slime and SEM for large inclusions, nitrogen pickup for reoxidation, and slag composition analysis to investigate inclusion absorption and slag entrainment. [108] Finally, ultrasonic scanning, microscope observation, sulfur printing, slime electrolysis, X-ray, SEM, slag composition analysis, and refractory observation are suitable methods to detect exogenous inclusions.…”

Section: Slag Composition Measurementmentioning

confidence: 99%

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State of the art in the control of inclusions during steel ingot casting

Zhang

Thomas

2006

Metall Mater Trans B

253

129

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This article extensively reviews published research on inclusions in ingot steel and defects on ingot products, methods to measure and detect inclusions in steel, the causes of exogenous inclusions, and the transport and entrapment of inclusions during fluid flow, segregation, and solidification of steel cast in ingot molds. Exogenous inclusions in ingots originate mainly from reoxidation of the molten steel, slag entrapment, and lining erosion, which are detailed in this article. The measures to prevent the formation of exogenous inclusions and improve their removal are provided, which are very useful for the clean steel production of ingot industries.

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Influence of Deformation Degree on the Evaluation of Macroscopic Oxide Cleanness

Jacobi

2006

steel research international

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The demand for cleaner steels requires reducing the number of macroscopic non‐metallic oxide inclusions. A major problem of “clean steel” is the measurement and evaluation of the rare large inclusions which exceed a critical size harmful to the product. To this end, volumetric methods of evaluating macro‐inclusions in the three‐dimensional steel matrix are necessary to qualify steel heats or continuous cast slabs and to check if the refining and casting processes are stable and have been improved. Ultrasonic scans are a powerful tool to assess the quality of the volume. In order to activate macroscopic oxide inclusions for the reflexion of the ultrasound, as‐cast material is deformed by hot rolling. The aim of the present research work was to find out the most effective hot rolling practice with respect to ultrasonic detection of the rare large oxide inclusions. For this purpose, heavily contaminated neighbouring slab samples, corresponding to a severe incidence of ladle slag carryover, were hot rolled in a different manner. The 23‐kg‐samples were either elongated by a ratio λ = 2, 3, 10 or 15, or alternatively cross‐rolled, e.g. spread and stretched by ratios 2 × 5 or 3.2 × 3.2. The best compromise to quantify macroscopic steel cleanliness under consideration of cost and time requirements is based on the pure 10fold elongation or the cross‐rolling by 2fold x 5fold. It likewise became clear that rare large oxides can be detected with good sensitivity, as long as the hot rolling reduction ratio is large enough.

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Methodology of steel cleanliness assessment

Cited by 14 publications

References 0 publications

State of the Art in Evaluation and Control of Steel Cleanliness.

State of the Art in Evaluation and Control of Steel Cleanliness.

State of the art in the control of inclusions during steel ingot casting

Influence of Deformation Degree on the Evaluation of Macroscopic Oxide Cleanness

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