Determination of Micro-alloyed Elements Containing in the Solid Solution Phase in High Tensile Steel

Abstract

For the steel making control with micro-alloyed elements, it is essential to accurately analyze the distribution of those elements between different metallurgical phases in steel. The micro-alloyed elements contained in precipitates have been analyzed by conventional chemical or electrochemical procedures, selectively dissolving the Fe matrix by electrolysis, and separating precipitates as insoluble particles from the matrix by filtration. But this method has become inadequate to analyze the fine precipitates because some of the fine precipitates extracted are unavoidably uncollected. Hence, we have developed a quantitative analysis for micro-alloyed elements containing in the solid solution phase of steel, named solute elements, by using of analyzing a portion of the electrolytic solution. By electrolysis, solute elements are dissolved into the electrolyte, and the precipitates remain on the surface of the sample as insoluble particles. So, the analysis of the electrolytic solution during or after electrolysis enables the determination of solute elements directly. For certified reference materials, the sum total of concentration of solute element analyzed by this method and the precipitate analyzed by conventional method suits a certified value substantially on the micro-alloyed element. However, for the samples that contain fine precipitates, they are not in agreement with the total content obtained by the spark-OES. It is estimated that the precipitates not collected by filtration in the conventional method cause the disagreement. It shows the proposed method, which analyzes solute elements directly, is useful for estimating the distribution of the microalloyed elements between different metallurgical phases.

Determination of Alloying Elements Ti, Nb, Mn, Ni, and Cr in Double-Stabilized Ferritic Stainless Steel Process Sample Using an Electrolytic Extraction Method and Separate Analysis of Inclusions

“…An alkali fusion technique might be necessary in the dissolution of inclusions when carbide-forming elements are determined. [5,9,20] Kinoshiro et al [4] obtained good results in the determination of microalloying elements Ti, Nb, V, and Mo from reference materials. Depending on the reference materials, microalloying elements were present in the sample in soluble form or insoluble form.…”

“…[5,9] The determination of alloying elements from the steel lattice and insoluble particles with acid digestion after sample dissolution using electrolytic extraction is fairly a new method of analysis for steel purity. [4] Precise information about steel's chemical composition is required when new, more intricate steels are manufactured. Steel composition studies are particularly interesting when rare and expensive alloying elements such as Nb and Hf are used.…”

“…An electrolytic extraction method is used in 3D inclusion studies and also in the study of soluble and insoluble alloying elements from deoxidized ferrous materials and stainless steel. [4][5][6][7][8] The alkali fusion method has been used in the elemental analysis of inclusions. [5,9] The determination of alloying elements from the steel lattice and insoluble particles with acid digestion after sample dissolution using electrolytic extraction is fairly a new method of analysis for steel purity.…”

Mechanism of Improved Ductility of 1500 MPa-class Ultra-high Strength Cold-rolled Steel Sheet Produced by Rolling and Partitioning Method

“…27) After all the extracted residues were decomposed with a mixed acid, the chemical contents (mass%) of Mo and Cr in the residues (carbide-based) were analyzed with an inductively coupled plasma (ICP) analyzer. 28) Regarding the microstructure analysis, a phase map was obtained from the EBSD image taken at the center of a cross section parallel to the rolling direction (RD) of the sample, which was analyzed using an OIM device (made by TSL Solutions Co., Ltd.) attached to an FE-SEM (JSM-7001F, JEOL Co., Ltd.). Furthermore, to more quantitatively compare the phase composition and the microstructural change in the bulk condition, using the beam-line 20, iMATERIA, 29) at Japan Proton Accelerator Research Complex (J-PARC), Materials and Life Science Experiment Facility (MLF), both the crystalline texture and the lattice parameters were measured using stacked samples comprising 46 sheets, each of 8 mm width, 65 mm length, and 0.13 mm thickness.…”