Intergranular and Internal Oxidation during Hot-rolling Process in Ultra-low Carbon Steel.

Kizu, Taro; Nagataki, Yasunobu; Inazumi, Toru; Hosoya, Yoshihiro

doi:10.2355/isijinternational.42.206

Cited by 8 publications

(3 citation statements)

References 10 publications

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“…The small particles containing copper in the scale didn't have any connection with the oxidic layer and base material interface. The internal oxidation particles in the vicinity of slivers were the convincing argument of slivers caused by overheating the material in reheat furnace [4].…”

Section: Discussionmentioning

confidence: 99%

Surface Defect on Hot Rolled Steel Sheet with Cu Content

Hrabčáková¹,

Duška²,

Mašlejová³

2014

MSF

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Structural steel grades S235JRCCu+N and S355JRCCu+N with 0.25 – 0.35% copper content are intended for products with increased corrosion resistance. They are used for railcar and container bodies. The low copper alloying strongly increases the material life-time in the conditions of atmospheric corrosion. Sheets with fine sharp needle-type bodies on both sheet surfaces were delivered for the analysis. As per the customer information, they were present on almost whole length of on cast strips. Considering the steel copper content, it was assumed that the improper steel alloying was the reason of imperfection. Chemical composition results didn’t confirm this expectation. Metallographic analysis should determine the imperfection origin and decide if copper presence was the primary factor of it. The analyses using SEM coupled with EDS analyzer have shown that the sliver-type defects, few millimeters long bands of ductile iron oxides, were present in very small material depth of about 50 – 150 μm in the analyzed material The bands were formed in more layers parallel to the sheet surface; their thickness was similar to the thickness of surface scales. Oxidic material under the sliver had the same micro-morphology and chemical composition like the scales on the sheet surface. Very fine globular copper particles were randomly and very sporadically present in the layer of ductile oxides in slivers and also in surface scale. Besides this, the material in defect area was chemically homogeneous and no particles were found in the layer boundaries. Copper particles were not detected in the steel basic material; the copper was dissolved in the matrix. The nature of imperfection was typical for V-shaped slivers, caused by overheating sheet surface in reheat furnace. After revising technical conditions of reheat furnace operation, this imperfection type was suppressed.

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Section: Discussionmentioning

confidence: 99%

Surface Defect on Hot Rolled Steel Sheet with Cu Content

Hrabčáková¹,

Duška²,

Mašlejová³

2014

MSF

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“…27) If the oxidation temperature is sufficiently high, the liquid phase accelerates scaling and increases intergranular oxidation. [28][29][30][31][32][33][34] In the presence of intergranular oxidation, the formation of surface cracks is facilitated, and scale adhesion, as well as the occurrence of red scale defects, is favored. [35][36][37][38][39] Thus, for Si and tramp elements, liquid phases due to external or internal oxidation occur at temperatures close to 1150 °C, which is, as will be discussed later, a typical rolling temperature for hot strip production.…”

Section: Introductionmentioning

confidence: 99%

Influence of Silicon and Tramp Elements on the High-temperature Oxidation of Steel in Direct Casting and Rolling Processes

Gaiser,

Presoly,

Bernhard

et al. 2024

ISIJ Int.

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Oxidation processes are unavoidable in continuous casting and further hot processing of steel. A deeper understanding of the occurring phenomena such as intergranular oxidation and liquid metal infiltration of grain boundaries is essential to continuously improve the quality of the products. In this study, oxidation experiments were performed with simultaneous thermal analysis for two thin slab casting and rolling applications under near-process conditions up to the point prior to the first reduction stage. The experiments were performed for two low-carbon steels contaminated with undesirable tramp elements (Cu, Sn, …). In addition, the two steels contain Silicon at different levels. The results show that for the "Endless Strip Production" process (ESP), intergranular oxidation is significantly less pronounced compared to a "Thin Slab Casting and Rolling process" with a gasfired tunnel furnace (TSCR TF). Due to the short process time at high temperatures in the ESP process, hardly any liquid metal infiltration by copper appears. In low silicon steel, intergranular oxidation results from various oxides, and liquid metal infiltration appears simultaneously in the TSCR TF process. Furthermore, the yield loss from oxidation is significantly higher in the TSCR TF process. The change from a natural gas combustion atmosphere to a hydrogen combustion atmosphere further increases the oxidation rate and results in a higher mass loss.

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“…The purpose of this research was to observe the scaling in a time period similar to the time it takes a slab to travel through a reheat furnace. Other isothermal scaling studies have been conducted either in a time‐frame of under 90 min, or over 10 h . In this research, the time‐frame was set to 180 min according to an industry partner's average evaluation of the time a slab is in the reheat furnace.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Boron and Titanium Microalloying on the Scale Formation of AISI 304 Austenitic Stainless Steel in Simulated Walking Beam Furnace Conditions

Laukka

Heikkinen

Puukko

et al. 2017

steel research int.

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The effect of microalloying boron and titanium on AISI 304 austenitic stainless steel scale formation is studied. Thermogravimetric tests simulating walking beam furnace conditions are performed at temperatures of 800, 1100, and 1300 °C for 3 h on samples of AISI 304 steels with different alloying amounts of B and Ti. Scaling at 800 °C is negligible on all the samples, while scaling is clear at 1100 and 1300 °C. The thermogravimetric results show that even in small amounts, boron and titanium have an effect on scale growth rate. FESEM microscopy and accompanying EDS analyses are used to study oxidation area element composition. The FESEM images are also used to compare the oxidation zones’ area fractions of metal, pores, and oxide between different alloying amounts for the samples of 1300 °C tests. Calculations for scale formation activation energy are done based on the thermogravimetric data. The steel sample with the lowest alloying of boron and titanium shows a noticeably different growth rate, which is nearly linear in both the 1100 and 1300 °C tests. Differences between alloying amounts in accumulated scale during the 180 min period in kg m−2 are greater at 1100 °C than they are at 1300 °C.

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Intergranular and Internal Oxidation during Hot-rolling Process in Ultra-low Carbon Steel.

Abstract: Fig. 23. Effect of T and P O 2 on dϩx at 1 503 K.

Cited by 8 publications

References 10 publications

Surface Defect on Hot Rolled Steel Sheet with Cu Content

Surface Defect on Hot Rolled Steel Sheet with Cu Content

Influence of Silicon and Tramp Elements on the High-temperature Oxidation of Steel in Direct Casting and Rolling Processes

The Effect of Boron and Titanium Microalloying on the Scale Formation of AISI 304 Austenitic Stainless Steel in Simulated Walking Beam Furnace Conditions

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