A Study of the Oscillation Marks’ Characteristics of Continuously Cast Incoloy Alloy 825 Blooms

2016 ◽  
Vol 47 (8) ◽  
pp. 4068-4079 ◽  
Author(s):  
Saud Saleem ◽  
Michael Vynnycky ◽  
Hasse Fredriksson
Keyword(s):  
Continuously Cast ◽  
Incoloy Alloy ◽  
Oscillation Marks

Background of Branched Crack Formation in Surface Zone of Continuously-Cast Ti-Nb Microalloyed Steel Slab

2015 ◽  
Vol 1127 ◽  
pp. 143-149
Author(s):  
Pavel Bekeč ◽  
Margita Longauerová ◽  
Marek Vojtko ◽  
Ondrej Milkovič ◽  
Jiří Kadlec ◽  
...  
Keyword(s):  
Crack Formation ◽  
Microstructural Analysis ◽  
Thin Strip ◽  
Thick Sheet ◽  
Surface Zone ◽  
Slab Surface ◽  
Cast Slab ◽  
X Ray ◽  
Continuously Cast ◽  
Oscillation Marks

Branched cracks are undesirable and dangerous, and under the oxidized surface of a continuously-cast slab they are mostly difficult to identify. They can cause the formation of defects in thick sheet or on thin strip. This work deals with the study of the background to the formation of branched cracks in a continuously-cast slab, at pulling rate 0.43 m.min-1. The results of the work show that branched cracks extended to a depth of 10 mm below the slab surface and occurred mostly below oscillation marks. Cracks were mostly present in the edge parts of the slab, where they were also deeper in comparison with locations in the middle of the slab width. Microstructural analysis confirmed heterogeneity of ferrite grain sizes in the slab surface skin. The microstructure was formed predominantly of polyhedral ferritic-pearlitic grains, and on the ferritic grain boundaries the presence of tertiary cementite was observed. In the area around the cracks mainly non-equilibrium microstructure of acicular character was observed. A typical feature of these cracks after their opening is intercrystalline fracture. Wavelength-dispersive X-ray analysis of a sample with a branched crack showed chemical heterogeneity of harmful elements, mainly S and As. Large amounts of these elements point to their significant segregation. The formation of branched cracks is conditioned not only by segregation of impurities, but possibly also by the presence of undesirable brittle cementite networks. The presence of cementite was confirmed not only by microstructural analysis, but also diffraction of hard X-ray radiation. Precipitation of microalloying elements in connection with the cementite can lead to higher probability of surface crack formation, as also confirmed in this study.Keywords: slab, branched cracks, oscillation marks, segregation, precipitation

Transverse Surface Cracks in Continuously Cast Steel Slabs, Oscillation Marks and Austenite Grain Size

2010 ◽  
Vol 638-642 ◽  
pp. 3603-3609 ◽  
Author(s):  
Rian Dippenaar
Keyword(s):  
Grain Size ◽  
Low Carbon Steel ◽  
Surface Cracks ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Continuously Cast ◽  
Steel Slabs ◽  
Ferrite Films ◽  
Oscillation Marks

Transverse surface cracks in low carbon steel slabs are invariably inter-granular and follow the soft ferrite films outlining the grain boundaries of exceptionally large prior-austenite grains often found at the roots of oscillation marks in continuously cast low-carbon steel slabs. Plastic deformation is concentrated in the ferrite films and cracks initiate in the ferrite films, leading to crack propagation along the austenite grain boundaries. Hot-ductility is significantly reduced by an increase in austenite grain size and in situ observations revealed that depending on the cooling rate, austenite can nucleate and grow by diffusional mechanisms or forms by a massive type of reaction. The delta-ferrite transformation has also been studied by using neutron diffraction techniques and high-energy X-rays in a synchrotron.

Influence of technology parameters of free-cutting steel continuous casting on the billet internal structure

2020 ◽  
Vol 76 (2) ◽  
pp. 139-142
Author(s):  
A. T. Kunakbaeva ◽  
A. M. Stolyarov ◽  
M. V. Potapova
Keyword(s):  
Regression Analysis ◽  
Continuous Casting ◽  
Internal Structure ◽  
Sulfur Content ◽  
Manganese Content ◽  
High Quality ◽  
Correlation And Regression Analysis ◽  
Cutting Steel ◽  
Continuously Cast

Free-cutting steel gains specific working properties thanks to the high content of sulfur and phosphorus. These elements, especially sulfur, have a rather high tendency to segregation. Therefore, segregation defects in free-cutting steel continuously cast billets can be significantly developed. The aim of the work was to study the influence of the chemical composition of freecutting steel and casting technological parameters on the quality of the macrostructure of continuously cast billets. A metallographic assessment of the internal structure of cast metal made of free-cutting steel and data processing by application of correlation and regression analysis were the research methods. The array of production data of 43 heats of free-cutting steel of grade A12 was studied. Steel casting on a five-strand radial type continuous casting machine was carried out by various methods of metal pouring from tundish into the molds. Metal of 19 heats was poured with an open stream, and 24 heats – by a closed stream through submerged nozzles with a vertical hole. High-quality billets had a cross-sectional size of 150×150 mm. The macrostructure of high-quality square billets made of free-cutting steel of A12 grade is characterized by the presence of central porosity, axial segregation and peripheral point contamination, the degree of development of which was in the range from 1.5 to 2.0 points, segregation cracks and strips – about 1.0 points. In the course of casting with an open stream, almost all of these defects are more developed comparing with the casting by a closed stream. As a result of correlation and regression analysis, linear dependences of the development degree of segregation cracks and strips both axial and angular on the sulfur content in steel and on the ratio of manganese content to sulfur content were established. The degree of these defects development increases with growing of sulfur content in steel of A12 grade. These defects had especially strong development when sulfur content in steel was of more than 0.10%. To improve the quality of cast metal, it is necessary to have the ratio of the manganese content to the sulfur content in the metal more than eight.

Minimization of Thermal Stresses in Continuously-Cast Ingot with Restriction on its Molten-Metal Pool Volume

1999 ◽  
Vol 30 (4-6) ◽  
pp. 296-302
Author(s):  
F. V. Nedopekin ◽  
Victor K. Tolstykh ◽  
N. A. Volodin ◽  
V. V. Belousov ◽  
S. V. Gridin
Keyword(s):  
Molten Metal ◽  
Thermal Stresses ◽  
Metal Pool ◽  
Cast Ingot ◽  
Continuously Cast ◽  
Molten Metal Pool

Improvement of Continuously Cast Slab Surface and Performance of Rolling the Slab Free from Surface Conditioning

1981 ◽  
Vol 67 (8) ◽  
pp. 1229-1235 ◽  
Author(s):  
Minoru KITAMURA ◽  
Tosiyuki SOEJIMA ◽  
Sinzi KOYAMA ◽  
Yosihiro MATUDA ◽  
Junji ABU ◽  
...  
Keyword(s):  
Slab Surface ◽  
Cast Slab ◽  
Surface Conditioning ◽  
Continuously Cast ◽  
And Performance

Development of Rolling Technique for Large H-shapes from Continuously Cast Slabs

1981 ◽  
Vol 67 (15) ◽  
pp. 2483-2492
Author(s):  
Tadaaki YANAZAWA ◽  
Teruaki TANAKA ◽  
Masashi YAMASHITA ◽  
Hiroshi OKUMURA ◽  
Takashi KUSABA
Keyword(s):  
Rolling Technique ◽  
Continuously Cast

INCOLOY ALLOY 890

Alloy Digest ◽  
2003 ◽  
Vol 52 (8) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
High Temperature Corrosion ◽  
Temperature Performance ◽  
Incoloy Alloy

Abstract Alloy 890 provides improved properties over those of Incoloy alloys 800HT and 803 via the addition of silicon and molybdenum to optimize the performance of the alloy. Alloy 890 is typically 43% Ni, 25% Cr, 1.85 Si, 1.5% Mo, and 0.45% Nb, with the balance being principally iron. The alloy offers a significant improvement in resistance to high-temperature corrosion. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, and joining. Filing Code: Ni-611. Producer or source: Special Metals Corporation.

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