Non-metallic inclusions interpretation technique for factory expertise of metal product defects

Kazakov, A. A.; Murysev, V. A.; Kiselev, D. V.

doi:10.17580/cisisr.2021.02.08

Cited by 2 publications

(3 citation statements)

References 9 publications

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“…It follows from the Table 1, that slags and refractory materials do not serve as a source of sulfur in non-metallic inclusions, so CaS in their composition should be definitely related to products of steel modification by calcium. The authors of publications [5][6][7][8][9][10][18][19][20] have the same opinion, however, several of them [6][7][8][9] have wrongly associated the origin of CaO and Al 2 O 3 in the inclusions found in discontinuities of defects, with exogenous particles of slag. It is impossible to agree with this, since all the slags used during secondary steelmaking and casting still include SiO 2 , especially in the tundish and mould, where its concentration, calculated on the silicon content, reaches 30% (Table 1).…”

Section: Sources Of Exogenous Non-metallic Inclusionsmentioning

confidence: 99%

“…Earlier, we developed a "cluster" technique for interpretation of composition of nonmetallic inclusions found in discontinuities of HFIW welds, which allowed us to summarize many years of factory experience in studying these defects in steels 09G2S [19] and 22GYu [20]. Compositions of NMIs calculated by thermodynamic simulation were combined into the first type of clusters of indigenous deoxidation and modification products.…”

Section: Introductionmentioning

confidence: 99%

“…Summarizing more than 400 compositions of inclusions found mainly in the hook cracks of welded joints, it is proved that they are conglomerates consisting of deoxidation products absorbed on the surface of the refractories of metal wiring. These conglomerates, separated by the onset flow of steel melt from the surface of refractories together with the particles of these refractories, get into the mould, also after the interaction with its slag [19][20]. Such coarse conglomerates cannot penetrate deeply into the solidifying slab, so after its rolling they all find themselves at the edges of the sheet.…”

Section: Introductionmentioning

confidence: 99%

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Non-metallic inclusions and hook cracks of high-frequency induction welded pipes

Kazakov¹,

Kiselev²,

Murysev³

et al. 2022

cisisr

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Based on the analysis of foreign experience, it is shown that hook cracks are the most common defect of pipe joints obtained by high-frequency induction welding (HFIW). Particular attention is paid to the non-metallic inclusions (NMIs) that caused this defect. Their composition, origin and ways of elimination are considered. It was found that in the foreign literature the nature of certain oxides found in the vicinity of defects is often declared without objective evidence of their origin. The interpretation technique of NMIs composition, which caused the formation of defects of pipe joints obtained by HFIW, is presented. This technique is a part of the "Metal products quality system", implemented on the basis of Thixomet image analyzer, working in the laboratories of Vyksa Steel Works JSC. The compositions of NMIs found in the discontinuities of welded joint defects of 09G2S steel grade were interpreted using thermodynamic simulation of primary NMIs and generalized for two sets of 65 and 70 defects in each set. These compositions differ significantly from each other and correspond to the following indigenous inclusions: Al 2 O 3 , MgO•Al 2 O 3 , calcium aluminates, CaO and CaS. The same compounds can form exo-indigenous NMIs conglomerates after the interaction between liquid calcium aluminates and refractories based on MgO or ZrO 2 , and/or mould powder. The unique ranges of concentration changes of the main elements included in individual phases and their combinations in NMIs conglomerates are used for automated determination of their origin when conducting metallographic examination of defects using the Thixomet image analyzer. Examples of using the origin of NMIs to find the exact place in the secondary steelmaking and steel casting technologies for their improvement and on this basis to improve the quality of HFIW pipe joints are also presented.

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Section: Sources Of Exogenous Non-metallic Inclusionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-metallic inclusions and hook cracks of high-frequency induction welded pipes

Kazakov¹,

Kiselev²,

Murysev³

et al. 2022

cisisr

View full text Add to dashboard Cite

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PHASE FORMATION DURING STEEL REFINING BY ALLOYS WITH ALKALINE EARTH ELEMENTS (Ba, Mg, Sr)

MAKROVETS,

BAKIN,

MIKHAILOV

2022

Černaâ metallurgiâ. Bûlletenʹ naučno-tehničeskoj informacii

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Important factors affecting the quality of steel are both the level of metal contamination with non-metallic inclusions and the properties of these inclusions. Hard-to-remove magnesium-containing compounds have a pronounced negative effect on the performance of metal products. This type of inclusions is distinguished by a high melting point, a characteristic acute-angled shape, and a significant difference in the coefficient of thermal expansion from the matrix material. Despite the fact that the magnesium-containing modifiers are practically not used for out-of-furnace processing of steel and the magnesium-containing inclusions are mostly exogenous, the task of their removal from the metal is extremely important. At present, to improve the quality of metal, especially low-alloyed metal, out-of-furnace steel processing technologies are used using complex alloys, which include barium and strontium. The study of the effect of barium and strontium additives on the processes of liquid steel refining is one of the promising areas of research in the field of metallurgical technologies. This paper presents the results of thermodynamic studies of phase equilibria in the Fe–Mg–Ba–Sr–O and Fe–Mg–Ba–Sr–O–C systems. Based on the literature data and our own research, we have constructed the phase diagram of the BaO–MgO–SrO ternary system for the first time. For the systems under study, the component solubility surfaces (SSS) in liquid iron were constructed for steel treatment temperatures of 1550 and 1600 ºС. According to the calculations, the most probable type of inclusions are solid solutions based on magnesium oxides. As the temperature decreases, the probability of participation of strontium and barium in the steel refining process increases, which creates conditions for the formation of easily removed barium- and strontium-containing non-metallic inclusions. The gas phase formed in the presence of carbon creates additional conditions for efficient refining of the melt.

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Non-metallic inclusions interpretation technique for factory expertise of metal product defects

Cited by 2 publications

References 9 publications

Non-metallic inclusions and hook cracks of high-frequency induction welded pipes

Non-metallic inclusions and hook cracks of high-frequency induction welded pipes

PHASE FORMATION DURING STEEL REFINING BY ALLOYS WITH ALKALINE EARTH ELEMENTS (Ba, Mg, Sr)

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