JOPSS - Search Results

This study discusses the creep-fatigue strength for Mod.9Cr-1Mo steel at a high temperature under multiaxial loading. A low-cycle fatigue tests in various strain waveforms were performed with a hollow cylindrical specimen. The low cycle fatigue test was conducted under a proportional loading with a fixed axial strain and a non-proportional loading with a 90-degree phase difference between axial and shear strains. The low cycle fatigue tests at different strain rates and the creep-fatigue tests at different holding times were also conducted to discuss the effects of stress relaxation and strain holding on the failure life. In this study, two types of multiaxial creep-fatigue life evaluation methods were proposed: the first method is to calculate the strain range using Manson's universal slope method with considering a non-proportional loading factor and creep damage; the second method is to calculate the fatigue damage by considering the non-proportional loading factor using the linear damage law and to calculate the creep damage from the improved ductility exhaustion law. The accuracy of the evaluation methods is much better than that of the methods used in the evaluation of actual machines such as time fraction rule.

Journal Articles

Hydrogen permeation property of bulk cementite

Adachi, Nozomu*; Ueno, Haruki*; Onoe, Katsuhiko*; Morooka, Satoshi; Todaka, Yoshikazu*

ISIJ International, 61(8), p.2320 - 2322, 2021/08

https://doi.org/10.2355/isijinternational.ISIJINT-2021-134

Times Cited Count：3 Percentile：25.78(Metallurgy & Metallurgical Engineering)

Journal Articles

Hydrogen absorption mechanism into iron in aqueous solution including metal cations by laser ablation tests and first-principles calculations

Igarashi, Takahiro; Otani, Kyohei; Kato, Chiaki; Sakairi, Masatoshi*; Togashi, Yusuke*; Baba, Kazuhiko*; Takagi, Shusaku*

ISIJ International, 61(4), p.1085 - 1090, 2021/04

https://doi.org/10.2355/isijinternational.ISIJINT-2020-065

Times Cited Count：1 Percentile：8.06(Metallurgy & Metallurgical Engineering)

In order to clarify the effect of metal cations (Zn $^{2+}$ , Mg $^{2+}$ , Na $^{+}$ ) in aqueous solution on hydrogen permeation into iron, the amount of hydrogen permeation from iron surface was measured by electrochemical tests with a laser ablation. Moreover, in order to obtain the basic mechanism of hydrogen permeation with metal cation, first-principles calculations were used to acquire the adsorption potential of the metal cation and the electronic state around iron surface. By Zn $^{2+}$ in solution, anodic reaction on ablated surface by laser irradiation was suppressed. Also, by quantum analysis Zn atoms were chemically bonded stronger than Na and Mg atoms to iron surface. It was suggested that the dissolution reaction of iron was suppressed by the formation of the Zn layer, and that lead suppression of hydrogen permeation into iron.

Journal Articles

Effects of stress and plastic strain on hydrogen embrittlement fracture of a U-bent martensitic steel sheet

Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Matsuno, Takashi*; Akiyama, Eiji*

ISIJ International, 61(4), p.1322 - 1329, 2021/04

https://doi.org/10.2355/isijinternational.ISIJINT-2020-569

Times Cited Count：3 Percentile：25.78(Metallurgy & Metallurgical Engineering)

Journal Articles

Effects of residual stress on hydrogen embrittlement of a stretch-formed tempered martensitic steel sheet

Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*

ISIJ International, 61(4), p.1170 - 1178, 2021/04

https://doi.org/10.2355/isijinternational.ISIJINT-2020-492

Times Cited Count：3 Percentile：25.78(Metallurgy & Metallurgical Engineering)

Journal Articles

Relation between intergranular stress of austenite and martensitic transformation in TRIP steels revealed by neutron diffraction

Harjo, S.; Kawasaki, Takuro; Tsuchida, Noriyuki*; Morooka, Satoshi; Gong, W.*

ISIJ International, 61(2), p.648 - 656, 2021/02

https://doi.org/10.2355/isijinternational.ISIJINT-2020-503

Times Cited Count：5 Percentile：41.35(Metallurgy & Metallurgical Engineering)

Journal Articles

Mechanism of improved ductility of 1500 MPa-class ultra-high strength cold-rolled steel sheet produced by rolling and partitioning method

Hosoya, Yoshihiro*; Matsumura, Yuta*; Tomota, Yo*; Onuki, Yusuke*; Harjo, S.

ISIJ International, 60(9), p.2097 - 2106, 2020/09

https://doi.org/10.2355/isijinternational.ISIJINT-2020-027

Times Cited Count：5 Percentile：31.59(Metallurgy & Metallurgical Engineering)

Journal Articles

Role of metal cations on corrosion of coated steel substrate in model aqueous layer

Islam, M. S.*; Otani, Kyohei; Sakairi, Masatoshi*

ISIJ International, 58(9), p.1616 - 1622, 2018/09

https://doi.org/10.2355/isijinternational.ISIJINT-2018-071

Times Cited Count：5 Percentile：27.74(Metallurgy & Metallurgical Engineering)

To elucidate the role of Zn $^{2+}$ on corrosion of coated steel, the effects of metal cations on the corrosion of carbon steel in the concentrated Cl $^{-}$ aqueous solutions were studied by immersion tests, surface analysis and electrochemical tests. Among the examined metal cations, Zn $^{2+}$ showed the significant effect on corrosion inhibition of carbon steel in the Cl $^{-}$ aqueous solution at high concentration. XPS analysis results elucidated that Zn $^{2+}$ can remain on the steel surface after immersed in the solutions with Zn $^{2+}$ . EIS measurements showed higher impedance in the solution with Zn $^{2+}$ than other solutions, and the results suggested that Zn $^{2+}$ reduced the defect points in the thin oxide film by forming a metal cation layer. Based on the experimental results, Zn $^{2+}$ may form a layer on the oxide film that protects the Cl $^{-}$ attack in the solution. The findings demonstrated that the formation of Zn layer on the oxide film is one of the main reason for showing high and longtime corrosion resistance of Zn coated steel substrate.

Journal Articles

Distribution and anisotropy of dislocations in cold-drawn pearlitic steel wires analyzed using micro-beam X-ray diffraction

Sato, Shigeo*; Shobu, Takahisa; Sato, Kozue*; Ogawa, Hiromi*; Wagatsuma, Kazuaki*; Kumagai, Masayoshi*; Imafuku, Muneyuki*; Tashiro, Hitoshi*; Suzuki, Shigeru*

ISIJ International, 55(7), p.1432 - 1438, 2015/07

https://doi.org/10.2355/isijinternational.55.1432

Times Cited Count：13 Percentile：53.92(Metallurgy & Metallurgical Engineering)

To characterize the distribution and anisotropy of dislocations in cold-drawn pearlitic steel wires, X-ray diffraction line-profile analysis was performed using synchrotron radiation micro-beams. The plastic shear strain was generally more severe near the surface than the center of the wire, whereas the dislocation density distribution was almost constant from the center to the surface. On the other hand, the dislocation rearrangement, which evolves the dislocation cell structure, progressed closer to the surface. It was also revealed that a difference between the hardness in axial and transverse wire directions could be explained by anisotropic dislocation density. Line-profile analysis based on diffraction data at elevated temperatures was performed. Whereas the cementite recovery progressed at a constant rate, the ferrite phase recovery rate was temperature-dependent, suggesting that the ferrite phase recovery was less related to that of the cementite phase.

Journal Articles

Process evaluation of use of High Temperature Gas-cooled Reactors to an ironmaking system based on Active Carbon Recycling Energy System

Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro

ISIJ International, 55(2), p.348 - 358, 2015/02

https://doi.org/10.2355/isijinternational.55.348

Times Cited Count：8 Percentile：39.68(Metallurgy & Metallurgical Engineering)

Reducing coking coal consumption and CO $_{2}$ emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO $_{2}$ electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H $_{2}$ produced by IS (iodine-sulfur) process. Both the effects on saving of the coking coal and reduction of CO $_{2}$ emissions were greater in the RWGS system. It was the reason of the result that excess H $_{2}$ which was not consumed in the RWGS reaction was used as reducing agent in the BF as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H $_{2}$ production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO $_{2}$ emissions more efficiently by comparing CO $_{2}$ emissions reduction per unit heat of HTGR.

Journal Articles

Quantitative evaluation of CO $_{2}$ emission reduction of active carbon recycling energy system for ironmaking by modeling with Aspen Plus

Suzuki, Katsuki*; Hayashi, Kentaro*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji

ISIJ International, 55(2), p.340 - 347, 2015/02

https://doi.org/10.2355/isijinternational.55.340

Times Cited Count：19 Percentile：64.17(Metallurgy & Metallurgical Engineering)

Use of the Active Carbon Recycling Energy System in ironmaking (iACRES) has been proposed for reducing CO $_{2}$ emissions. To evaluate the performance of iACRES quantitatively, a process flow diagram of a blast furnace model with iACRES was developed using Aspen Plus, a chemical process simulator. CO $_{2}$ emission reduction and exergy analysis were performed by using mass and energy balance obtained from simulation results. The following CO $_{2}$ reduction methods were evaluated as iACRES: solid oxide electrolysis cells (SOEC) with CO $_{2}$ capture and separation (CCS), SOEC without CCS, and a reverse water-gas shift reactor powered by a high-temperature gas-cooled reactor. iACRES enabled CO $_{2}$ emission reduction by 3-11% by recycling CO and H $_{2}$ , whereas effective exergy ratio decreased by 1-7%.

Journal Articles

Numerical analysis of influence of hydrogen charging method on thermal desorption spectra for pre-strained high-strength steel

Ebihara, Kenichi; Iwamoto, Takashi*; Matsubara, Yukio*; Yamada, Hiroki*; Okamura, Tsukasa*; Urushihara, Wataru*; Omura, Tomohiko*

ISIJ International, 54(1), p.153 - 159, 2014/01

https://doi.org/10.2355/isijinternational.54.153

Times Cited Count：13 Percentile：53.33(Metallurgy & Metallurgical Engineering)

For understanding the mechanism of hydrogen embrittlement that is one cause of stress corrosion cracking, it is necessary to identify the location of hydrogen segregation (hydrogen existing state) in steels. The thermal desorption spectrum of hydrogen that is obtained by measuring hydrogen desorbing from specimens heated at a constant rate is a useful data for identifying the hydrogen existing state. In the paper, using the numerical simulation, we examined the difference of the thermal desorption spectra between two specimens of pre-strained high-strength steel, one was charged with hydrogen by the method used widely in laboratories, the other was by the method simulating hydrogen penetration in real environment. As a result, it was found that the difference results from the difference of the initial hydrogen distribution caused by the amount of charged hydrogen. If the amount of charged hydrogen is small, the thermal desorption spectrum is more sensitive to the initial distribution.