EFFECT OF SLAB PULLING RATE ON FRACTURE CHARACTERISTICS AND NOTCH IMPACT TOUGHNESS OF SLAB SURFACE ZONE IN Ti-Nb MICROALLOYED STEEL

2013 ◽  
Vol 3 (0) ◽  
Author(s):  
Pavel Bekeč ◽  
Margita Longauerová ◽  
Marek Vojtko ◽  
Gabriel Tréfa ◽  
Gabriel Grimplini
Keyword(s):  
Impact Toughness ◽  
Microalloyed Steel ◽  
Surface Zone ◽  
Slab Surface ◽  
Fracture Characteristics ◽  
Nb Microalloyed Steel

Influence of Casting Rate on TiNb Microalloyed Steel Slab Surface Area Microstructure

2014 ◽  
Vol 782 ◽  
pp. 81-86 ◽  
Author(s):  
Pavel Bekeč ◽  
Margita Longauerová ◽  
Marek Vojtko
Keyword(s):  
Microalloyed Steel ◽  
Casting Rate ◽  
Surface Zone ◽  
Slab Surface ◽  
Aluminum Oxides ◽  
Grain Sizes ◽  
Steel Slab ◽  
Nb Microalloyed Steel ◽  
Oscillation Marks ◽  
Equilibrium Microstructure

Two slabs of Ti-Nb microalloyed steel were analysed in this work. The first slab was transitional with the initial pulling rate 0.43 m.min-1 and the final pulling rate 0.9 m.min-1. The second slab was cast at the real production pulling rate 1.03 m.min-1. The presence of larger amounts of oscillation marks was observed on the first slab at both pulling rates. The second slab showed no oscillation marks. At the lowest pulling rate, cracks were discovered below the slab surface, often below oscillation marks. Cracks were seldom observed at pulling rate 0.9 m.min-1. In the first slab, especially at the low pulling rate, the presence of cracks and pores was found. Pores were observed often with clusters of aluminum oxides. The microstructure of the slab surface zone was characterised by heterogeneity of ferrite grain sizes at all three pulling rates. This heterogeneity was manifested mainly in the marginal cut-outs at all pulling rates. In the marginal cut-outs the microstructure was granulometrically finer at all three pulling rates than in the central cut-outs. Non-equilibrium microstructure in the marginal cut-outs was also observed.

Effect of transformation texture on the impact toughness of hot-rolled Ti + Nb microalloyed steel

2017 ◽  
Vol 128 ◽  
pp. 86-97 ◽  
Author(s):  
K.N. Sasidhar ◽  
T. Dhande ◽  
N. Javed ◽  
A. Ghosh ◽  
M. Mukherjee ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Microalloyed Steel ◽  
Transformation Texture ◽  
Nb Microalloyed Steel ◽  
Hot Rolled ◽  
The Impact

INFLUENCE OF COOLING RATE ON TiNb MICROALLOYED STEEL SLAB SURFACE ZONE FRACTURE MORPHOLOGY

2013 ◽  
Vol 3 (0) ◽  
Author(s):  
Margita Longauerová ◽  
Pavel Bekeč ◽  
Marek Vojtko ◽  
Svätoboj Longauer ◽  
Pavol Marek
Keyword(s):  
Cooling Rate ◽  
Microalloyed Steel ◽  
Fracture Morphology ◽  
Surface Zone ◽  
Slab Surface ◽  
Steel Slab

Effect of Controlled Hot Rolling Parameters on Microstructure of a Nb-Microalloyed Steel Sheet

2011 ◽  
Author(s):  
Daavood Mirahmadi Khaki ◽  
Amir Abedi ◽  
Francisco Chinesta ◽  
Yvan Chastel ◽  
Mohamed El Mansori
Keyword(s):  
Hot Rolling ◽  
Steel Sheet ◽  
Microalloyed Steel ◽  
Nb Microalloyed Steel

Microstructure Characteristics in Continuous Cooling Transformation of an Nb Microalloyed Steel

2011 ◽  
Vol 228-229 ◽  
pp. 72-76
Author(s):  
J. H. Yang ◽  
Q. Y. Liu
Keyword(s):  
Microalloyed Steel ◽  
Controlled Rolling ◽  
Controlled Cooling ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Microstructure Characteristics ◽  
Continuous Cooling ◽  
Nb Content ◽  
Nb Microalloyed Steel ◽  
Two Stages

Deformation dilatometry has been used to simulate controlled hot rolling followed by controlled cooling of a Nb microalloyed pipeline steels, the microstructure and transformation characteristics in the steel and the effect of deformation on transformation are studied. According to the results of both dilatometry measurements and microstructure observations, the continuous cooling transformation curves (CCT) of the tested steels are constructed. The results show that Nb content and deformation enhance the formation of acicular ferrite; the microstructure of the steel range from PF, QF to AF with increasing of cooling rates from 0.5 to 50°C /s in a two stages controlled rolling and the microstructure revolution is sensitive to cooling rates when it is lower than 5°C /s, however, when the cooling rate increasing further, the microstructure didn’t change very much but M/A constituents in matrix is refined and dispersed.

Local Notch Toughness of Slab Surface Zone in ULC/IF and HSLA Steels

2015 ◽  
Vol 662 ◽  
pp. 209-212
Author(s):  
Margita Longauerová ◽  
Maria Hurakova ◽  
Pavel Bekeč ◽  
Svätoboj Longauer ◽  
Mária Fedorová ◽  
...  
Keyword(s):  
Hsla Steel ◽  
Notch Toughness ◽  
Grain Structure ◽  
Surface Zone ◽  
Slab Surface ◽  
Slab Width ◽  
Fine Grain ◽  
Hsla Steels ◽  
Ferrite Structure ◽  
Ferrite Grain Size

The aim of this work was to analyze changes in local toughness KCV using Charpy V-notch impact tests in the slab surface zone in relation to the microstructure in ULC/ IF steel and TiNb HSLA steel. Marked heterogeneity in KCV values was confirmed in the surface zone across the width of transitional slabs. Distinct local differences in notch toughness across the slab width were found to be linked primarily with changes in ferrite grain size. Low KCV values in the analyzed steels were linked with coarse grain structure, while much finer ferrite structure was identified in tough samples. The heterogeneity of KCV vales in the analyzed steels may be influenced by differences in thickness of the fine-grain slab surface zone, and by the presence of tertial cementite and (in HSLA steel) of pearlite as well.

scholarly journals Effect of Ti(C, N) Particle on the Impact Toughness of B-Microalloyed Steel

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Yu Huang ◽  
Guo-Guang Cheng ◽  
Shi-Jian Li ◽  
Wei-Xing Dai ◽  
You Xie
Keyword(s):  
Impact Toughness ◽  
Microalloyed Steel ◽  
Fracture Initiation ◽  
Sem Analysis ◽  
Number Density ◽  
Size Number ◽  
Microalloying Elements ◽  
The Impact ◽  
Ti Content ◽  
Scanning Electron

Simultaneously improving the toughness and strength of B-microalloyed steel by adding microalloying elements (Nb, V, Ti) has been an extensively usedmethod for researchers. However, coarse Ti(C, N) particle will precipitate during solidification with inappropriate Ti content addition, resulting in poor impact toughness. The effect of the size, number density, and location of Ti(C, N) particle on the impact toughness of B-microalloyed steel with various Ti/N ratios was investigated. Coarse Ti(C, N) particles were investigated to act as the cleavage fracture initiation sites, by using scanning electron microscopy (SEM) analysis. When more coarse Ti(C, N) inclusions were located in ferrite instead of pearlite, the impact toughness of steel with ferrite–pearlite microstructure was lower. Meanwhile, when the size or the number density of Ti(C, N) inclusions was larger, the impact toughness was adversely affected. Normalizing treatment helps to improve the impact property of B-microalloyed steel, owing to the location of Ti(C, N) particles being partly changed from ferrite to pearlite. The formation mechanism of coarse Ti(C, N) particles was calculated by the thermodynamic software Factsage 7.1 and Thermo-Calc. The Ti(C, N) particles formed during the solidification of molten steel, and the N-rich Ti(C, N) phase precipitated first and, then, followed by the C-rich Ti(C, N) phase. Decreasing the Ti and N content is an effective way to inhibit the formation of coarse Ti(C, N) inclusions.

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