Effects of Ti alloying on resistance to hydrogen embrittlement in (Nb+Mo)-alloyed ultra-high-strength hot-stamping steels

Yoo, Jisung; Jo, Min Chul; Jo, Min Cheol; Kim, Seongwoo; Oh, Jinkeun; Bian, Jian; Sohn, Seok Su; Lee, Sunghak

doi:10.1016/j.msea.2020.139763

Cited by 37 publications

(21 citation statements)

References 64 publications

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“…Accordingly, high energy traps, uniformly distributed within the steel microstructure, might notably contribute to delaying hydrogen diffusion toward the aforementioned damage process zone ( Figure 1 b) in order to improve mechanical performance in hydrogen environments. For instance, the addition of carbide-forming elements (V, Ti, or Nb) was demonstrated to be effective in relieving hydrogen embrittlement susceptibility [ 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

The Positive Role of Nanometric Molybdenum–Vanadium Carbides in Mitigating Hydrogen Embrittlement in Structural Steels

et al. 2021

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The influence of hydrogen on the fracture toughness and fatigue crack propagation rate of two structural steel grades, with and without vanadium, was evaluated by means of tests performed on thermally precharged samples in a hydrogen reactor at 195 bar and 450 °C for 21 h. The degradation of the mechanical properties was directly correlated with the interaction between hydrogen atoms and the steel microstructure. A LECO DH603 hydrogen analyzer was used to study the activation energies of the different microstructural trapping sites, and also to study the hydrogen eggresion kinetics at room temperature. The electrochemical hydrogen permeation technique was employed to estimate the apparent hydrogen diffusion coefficient. Under the mentioned hydrogen precharging conditions, a very high hydrogen concentration was introduced within the V-added steel (4.3 ppm). The V-added grade had stronger trapping sites and much lower apparent diffusion coefficient. Hydrogen embrittlement susceptibility increased significantly due to the presence of internal hydrogen in the V-free steel in comparison with tests carried out in the uncharged condition. However, the V-added steel grade (+0.31%V) was less sensitive to hydrogen embrittlement. This fact was ascribed to the positive effect of the precipitated nanometric (Mo,V)C to alleviate hydrogen embrittlement. Mixed nanometric (Mo,V)C might be considered to be nondiffusible hydrogen-trapping sites, in view of their strong hydrogen-trapping capability (~35 kJ/mol). Hence, mechanical behavior of the V-added grade in the presence of internal hydrogen was notably improved.

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Section: Introductionmentioning

confidence: 99%

The Positive Role of Nanometric Molybdenum–Vanadium Carbides in Mitigating Hydrogen Embrittlement in Structural Steels

et al. 2021

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“…A comparison of the N-fixing abilities of the three different trace elements (V, Al, and Ti) revealed that the precipitation temperature of V (0.10%) was 800 • C, which is not effective for N-fixing at high temperatures. Although Al has the ability to fix the N, high content levels (0.07%) are needed to achieve the same result as that obtained by the trace Ti (0.015%) [5].…”

Section: Introductionmentioning

confidence: 89%

“…From the intersection of the curves, TiN began to precipitate at 0.89 of fs. Substituting fs into Equation (5) revealed that the TiN began to precipitate at 1710 K between…”

Section: Ti + N = Tin Inclusionmentioning

confidence: 99%

“…In the formula, [Ti] l , [N] l , [Ti] 0 , and [N] 0 represent the concentrations of Ti and N at the solidification front and their initial concentrations, respectively; k Ti and k N represent the equilibrium distribution coefficients of Ti and N, at 0.33 and 0.48, respectively. The temperature of the solidification front can be expressed by Equation (5).…”

Section: Thermodynamic Analysis Of Tin Formationmentioning

confidence: 99%

“…For solid solution in austenite, B segregates at the austenite grain boundary during the cooling process and inhibits the nucleation of grain boundary ferrite, improving the hardenability of steel, which in turn, substantially improves the uniformity of the properties and microstructure of the steel plate [3,4]. However, B can easily combine with N to generate BN, which largely reduces the solid solution of B and weakens the hardenability [3,5]. Previous studies have found that Ti plays an effective role in fixing the interstitial element N by forming high-temperature stable TiN, which can retain most of the free B.…”

Section: Introductionmentioning

confidence: 99%

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Study of the Fracture Behavior of TiN and TiC Inclusions in NM550 Wear-Resistant Steel during the Tensile Process

Liu

Zhong-yang

Liu

et al. 2022

Metals

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NM550 wear-resistant steel is widely used in large-scale engineering and mining machinery under extremely harsh working conditions. In NM550 steel, the addition of Ti can cause the formation of micron-scale TiN and TiC inclusions, easily triggering cleavage fractures. The fracture behavior and precipitation rule of micron-scale TiN and TiC inclusions on the tensile process in NM550 steel was investigated by scanning electron microscopy, transmission electron microscopy, and energy spectrum analysis combined with thermodynamic theory. The TiN precipitated in the solid–liquid two-phase region at a precipitation temperature of 1710 K, whereas that of TiC was 1158 K along the austenite grain boundary. The sizes of the TiN precipitated in the liquid phase and the TiC precipitated in austenite were both at the micron scale, which is prone to cleavage fracture during the stretching process. Under tensile stress, microcracks were first initiated at the TiN inclusion, which were further separated forming a hole, whereas the TiC inclusion was divided into two sections with a long and narrow gap formed between the substrates. The sizes of the TiN and TiC were related to the cooling rate, Ti, and N contents. The larger the cooling rate and the lesser the Ti and N content, the smaller the TiN and TiC sizes.

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Effect of Microalloyed Elements M (M = Ce, Ti, V, and Nb) on Mechanical Properties and Electronic Structures of γ‐Fe: Insights from a First‐Principles Study

Liu

Yang

Cai

et al. 2021

steel research int.

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Herein, the first-principles calculation is used to study the solid solution behavior of microalloyed elements M (M ¼ Ce, Ti, V, and Nb) in steel, and the effects of M on the mechanical properties and electronic structures of the doped systems are analyzed. The calculated results of the solvation energy and formation enthalpy show that Ce, Ti, V, and Nb can be solubilized in γ-Fe. The elastic modulus calculated results show that M doped reduces the incompressibility and rigidity and of the doped system, but the toughness and machinability are improved. A combination of Bader charge and differential charge density analysis shows that the metallic bond strength of the Fe-M system is weaker than that of the pure Fe system, which is the main reason for the decrease in incompressibility and rigidity of the doped system; the higher electron cloud density of the doped system is the main reason for its toughness increase.

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Effects of Ti alloying on resistance to hydrogen embrittlement in (Nb+Mo)-alloyed ultra-high-strength hot-stamping steels

Cited by 37 publications

References 64 publications

The Positive Role of Nanometric Molybdenum–Vanadium Carbides in Mitigating Hydrogen Embrittlement in Structural Steels

The Positive Role of Nanometric Molybdenum–Vanadium Carbides in Mitigating Hydrogen Embrittlement in Structural Steels

Study of the Fracture Behavior of TiN and TiC Inclusions in NM550 Wear-Resistant Steel during the Tensile Process

Effect of Microalloyed Elements M (M = Ce, Ti, V, and Nb) on Mechanical Properties and Electronic Structures of γ‐Fe: Insights from a First‐Principles Study

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