Formation of TiN Inclusions During Solidification of Titanium Micro-Alloyed Steel: Modeling With ChemAppPy

Liu, Dongming; Song, Shengqiang; Xue, Zhengliang; Zietsman, Johan; Qi, Jianghua; Deng, Zhixun

doi:10.1007/s11663-022-02699-9

Cited by 10 publications

(1 citation statement)

References 28 publications

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“…A coupling model combining the microsegregation, thermodynamics, and growth kinetics has been developed by the present authors to predict the size and amount of TiN inclusions precipitation at different cooling rates for different nitrogen and titanium contents. [ 24 ] The databases of “Fact PS” and “FS stel” in Factsage 8.0 have been used in this model. Wu et al [ 25 ] calculated the cooling rate of continuous casting plate in the range between 0.16 and 4.74 K s −1 .…”

Section: Discussionmentioning

confidence: 99%

Effect of Nitrogen Content on the High Cycle Fatigue Properties of Titanium Microalloyed Steel

Song

Jing

Xue

et al. 2023

steel research int.

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The high cycle fatigue properties of three industrial 0.12% Ti microalloyed steels with different nitrogen contents (56, 40, and 30 ppm in molten steel of tundish) are investigated. The results show that <20% of the fatigue crack initiation sites are oxide inclusions of size in 16.8 μm ≈ 55.9 μm, while the rest 80% are surface defects. No TiN inclusions cause fatigue failure and the fatigue limit strength slightly decreases with increasing N contents as the yield strength decreases with a coarser ferrite grain. Inclusions characterization in the section near the fracture shows that the average sizes of TiN inclusions in H56, M40, and L30 steels are 3.50, 3.22, and 2.89 μm, and the maximum sizes are 6.92, 6.67, and 6.23 μm, respectively. Calculating for a cooling rate of 0.2 K s−1 using ChemAppPy precipitation model, the size of TiN inclusions will increase from 6.1 to 7.1 μm, when increasing N content from 30 to 60 ppm. The relationships between nitrogen content, TiN inclusions, and fatigue failure quantified by experimental test and modeling show that the nitrogen content in steel can be relaxed up to 60 ppm when considering economical denitrogenization and fatigue safety.

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Section: Discussionmentioning

confidence: 99%

Effect of Nitrogen Content on the High Cycle Fatigue Properties of Titanium Microalloyed Steel

Song

Jing

Xue

et al. 2023

steel research int.

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Welding of P355NH steel for the construction of a medium-pressure gas pipeline

Szczucka-Lasota,

Węgrzyn,

Szymczak

et al. 2023

Continuum Mech. Thermodyn.

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There is an increasing demand for welding of steel pipes meant for pressure purposes. P355NH (1.0473) steel became an important construction material used for structuring and restructuring of a medium-pressure gas pipeline due to its properties, such as significant tensile strength at the level of 600 MPa and increased yield point. These properties ensure appropriate service life of the principal pipeline structures. When welding P355NH steel, processes that enable high-quality welds without significant changes in the chemical composition of the base material, are applied. It is recommended to use the TIG welding process to produce joints, although P355NH steel joints are considered as difficult to weld. During welding, various welding defects might appear, which mainly include sticking and lack of fusion. Creation of joints with the desired properties, including those used in the construction of medium pressure gas pipelines, with the required class B quality, requires selection of appropriate parameters and compliance with the welding process practice. This is very important for the service life of the structure. Therefore, the article aims to select the most appropriate parameters and thermodynamic conditions for welding P355NH steel in order to obtain the best mechanical properties. The most important of the tested welding parameters of P355NH steel is welding speed, welding current, preheating temperature, interpass temperature and, above all, the role of various shielding gases. (Three different shielding gases containing argon and helium additives were tested.) The obtained joints were tested by: non-destructive tests, such as VT—visual examination; MT—magnetic particle testing, PT—penetration tests, UT—ultrasonic testing and by the destructive methods, such as tensile strength, impact toughness, bending test, light microscopy and scanning electron microscopy. The cause-and-effect relationships between the obtained joint structure and its mechanical properties were determined. The considerations were supported by the nucleation model and the mechanisms of formation of the acicular ferrite phase in the joint material. The chosen parameters of TIG process allow to obtain joint with adequate strength for the production of the gases pipeline, without welding defects. The results have a practical implication, the developed production technology for the obtaining the joints. The presented solution gives the possibility of producing correct welded joints, which can be used in the responsible steel construction. The originality of manuscript is the presentation the newly, uncomplicated solution of obtaining joint with good mechanical properties included the thin-walled tubular structure with a thickness of 3.6 mm. A novelty in the article is a clear indication of the importance of detailed thermodynamic welding conditions and obtained weld structure on the mechanical properties of the P355NH steel joint, which lead to the formation of various non-metallic titanium inclusions, which have a decisive impact on the mechanical properties of the joint, especially its strength and impact strength.

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Characteristics of Secondary Oxide Inclusions in Si-Killed Spring Steel Bloom

Meng

et al. 2023

Metall Mater Trans B

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Formation of TiN Inclusions During Solidification of Titanium Micro-Alloyed Steel: Modeling With ChemAppPy

Cited by 10 publications

References 28 publications

Effect of Nitrogen Content on the High Cycle Fatigue Properties of Titanium Microalloyed Steel

Effect of Nitrogen Content on the High Cycle Fatigue Properties of Titanium Microalloyed Steel

Welding of P355NH steel for the construction of a medium-pressure gas pipeline

Characteristics of Secondary Oxide Inclusions in Si-Killed Spring Steel Bloom

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