Search Results 1-20 of 499

  • Rapid Evaluation of Hydrogen Embrittlement Resistance for Spot-Welds of High Tensile Strength Steel Sheet by Slow Rate Tensile Shear Test under Hydrogen Charging Conditions

    Kitahara Gaku , Matsuoka Hideaki , Asada Takashi

    … Rapid evaluation of the hydrogen embrittlement (HE) resistance for the spot-welds of AHSS sheets is required, since it is worried that the HE resistance of the nugget will deteriorate compared to the base metal due to the difference in microstructure caused by rapid cooling and solidification during spot welding. … The quasi-cleavage fracture surface and intergranular fracture surface were observed at the nugget and inside the crack generated at the nugget-heat affected zone interface. …

    MATERIALS TRANSACTIONS, 2021

    J-STAGE 

  • Development Technology for Prevention of Macro-segregation in Casting of Steel Ingot by Insert Casting in Vacuum Atmosphere

    Isobe Kohichi

    … The effectiveness of the proposed insert casting as a macro-segregation countermeasure was evaluated in the casting experiments with 0.5 mass% carbon steel using cast iron mold with a 150 mm square inner cross section, insulated to reduce solidification rate. …

    ISIJ International 61(5), 1556-1566, 2021

    J-STAGE 

  • Behavior of Crack Generation of Slag in Continuous Solidification Process of Blast Furnace Slag

    Ta Yasutaka , Hoshino Takeru , Tobo Hiroyuki , Watanabe Keiji , Takahashi Katsunori

    … <p>A continuous solidification process of blast furnace slag was developed to promote the use of air-cooled slag coarse aggregate for concrete. … Therefore, microscopic observation and thermal stress analysis of the solidified slag were carried out to clarify the mechanism of crack generation in the plate-like slag. …

    ISIJ International 61(5), 1716-1724, 2021

    J-STAGE 

  • Effect of (Ti, Mo)<sub>x</sub>C Particle Size on Wear Performance of High Titanium Abrasion-resistant Steel

    Wang Qi , Deng Xiangtao , Huang Long , Fu Tianliang , Jia Ye , Li Chengru , Wang Zhaodong

    … In this study, (Ti, Mo)<sub>x</sub>C-reinforced steels with the same composition were prepared though melt solidification processing using stepped molds of variable thicknesses to exclude the influence of the composition and hardness of the steel on the abrasion resistance. … The solidification rate was varied by the thickness of billets, which directly affected the nucleation and growth rates of the (Ti, Mo)<sub>x</sub>C particles. …

    ISIJ International 61(3), 985-992, 2021

    J-STAGE 

  • Calculation of Initial Stage of Solidified Shell Deformation during δ to γ Transformation in Mold  [in Japanese]

    Furumai Kohei , Zurob Hatem , Phillion Andre

    … <p>Solidification shell deformations within the mold during continuous casting have been calculated in order to clarify the influence of mold flux infiltration variability on the cooling rate, the width of the low heat flux region, the height of air gap, the unevenness of solidified shell, and the resulting strain in the solidified shell. …

    Tetsu-to-Hagane 107(2), 112-120, 2021

    J-STAGE 

  • Rapid Evaluation of Hydrogen Embrittlement Resistance for Spot-Welds of High Tensile Strength Steel Sheet by Slow Rate Tensile Shear Test under Hydrogen Charging Conditions  [in Japanese]

    Kitahara Gaku , Matsuoka Hideaki , Asada Takashi

    … Rapid evaluation of the hydrogen embrittlement (HE) resistance for the spot-welds of AHSS sheets is required, since it is worried that the HE resistance of the nugget will deteriorate compared to the base metal due to the difference in microstructure caused by rapid cooling and solidification during spot welding. … The quasi-cleavage fractured surface and intergranular fractured surface were observed at the nugget and inside the crack generated at the nugget-heat affected zone interface. …

    Journal of the Japan Institute of Metals and Materials 85(2), 75-83, 2021

    J-STAGE 

  • Cause of Cracking at Weld Corner of MIG-Welded 5083 Aluminum Alloy in HG-SCC Test  [in Japanese]

    GHORANI Alireza , ITOH Goro , OHBUCHI Tomoyuki

    … <p>In the previous study, we applied humid gas stress corrosion cracking <tt>(</tt>HG-SCC<tt>) </tt>test to metal inert gas <tt>(</tt>MIG<tt>) </tt>welded 5083 plate with an attention to the location of the pre-crack, and revealed that stress corrosion cracking <tt>(</tt>SCC<tt>) </tt>based on hydrogen embrittlement <tt>(</tt>HE<tt>) </tt>only progressed at weld metal region adjacent to base metal <tt>(</tt>weld corner<tt>)</tt>. …

    Journal of Light Metal Welding 59(1), 18-24, 2021

    J-STAGE 

  • Initially Solidified Shell Growth of Hypo-peritectic Carbon Steel in Continuous Casting Mold  [in Japanese]

    Mizukami Hideo , Shirai Yoshihisa , Hiraki Sei

    <p>The occurrence of longitudinal surface cracks in hypo-peritectic carbon steel slabs depends largely on the cooling capacity of the mold and the flow velocity of molten steel below the meniscu …

    Tetsu-to-Hagane 107(1), 53-63, 2021

    J-STAGE 

  • Development of Mold Flux for Continuous Casting of High-Carbon Steel Bloom  [in Japanese]

    Ohba Yasuhide , Yoshioka Takanori , Matsui Ryusuke , Hamaya Daisuke

    … In the casting with the developed mold flux, a film with a thickness of 3 mm was stably formed inside the mold to cover the meniscus, bleeding was prevented, and the frequency of surface crack defects on the bloom was reduced by 80%. … In the film of the developed mold flux, a 1.2 mm liquid layer lubricated the initial solidification shell.The increased thermal resistance at the film-mold interface reduced the heat flux in the mold, which contributed to the uniform initial solidification. …

    Tetsu-to-Hagane 107(1), 64-72, 2021

    J-STAGE 

  • Application of AI Reinforcement Learning to Hot Cracking Problem  [in Japanese]

    MAEDA Shintaro , Ni nshu MA , ODA Yusuke , IKUSHIMA Kazuki , SHIBAHARA Masakazu

    高温割れの発生には,溶接中の温度分布や変形挙動が影響することが知られており,溶接過渡の溶接条件を変更することで,割れが低減できる可能性がある.また,AI強化学習は,最終的な報酬を最大化するための最適な方策を決定することができる.本研究では,高温割れを防止する溶接条件の履歴を得ることを目的に,AI強化学習とFEM熱弾塑性解析を統合したシステムを構築し,高温割れ問題における強化学習の有用性について検証 …

    Preprints of the National Meeting of JWS 2020f(0), 202-203, 2020

    J-STAGE 

  • Study on Tack Welds Construction to Prevent Hot Cracking Using Genetic Algorithm  [in Japanese]

    MAEDA Shintaro , Ninshu MA , IKUSHIMA Kazuki , SHIBAHARA Masakazu

    仮付け溶接の長さや間隔などの施工条件によって,仮付け溶融時に大きな開き変形が生じ,高温割れが発生する可能性が考えられる.そこで本研究では,高温割れ問題において高温割れを防止する仮付け施工条件を得ることを目的に,遺伝的アルゴリズムとFEM熱弾塑性解析を統合したシステムを構築し,突合せ溶接解析時における高温割れ問題に適用することで,高温割れ問題における本手法の有用性について検証する.

    Preprints of the National Meeting of JWS 2020f(0), 204-205, 2020

    J-STAGE 

  • Characterization of Hot Cracking in Multi-Pass Weld Metal of High Manganese Austenitic Steel  [in Japanese]

    UEDA Keiji , YAMASHITA Shotaro , TAKADA Atsushi , SAHARA Naoki , OGURA Tomo , SAIDA Kazuyoshi

    … The fracture surface indicated a dendritic morphology and a bunching pattern, therefore it is considered that the crack in the multi-pass weld metal is caused by residual liquid film or remelting liquid film. … Varestraint test was carried out in order to clarify the characterization of the crack, and then the fracture surface of cracks obtained by the test was observed. …

    QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 38(4), 297-305, 2020

    J-STAGE 

  • Friction Stir Welding of High Phosphorus Weathering Steel– Weldabilities, Microstructural Evolution and Mechanical Properties  [in Japanese]

    Kawakubo Takumi , Nagira Tomoya , Ushioda Kohsaku , Fujii Hidetoshi

    … However, P causes solidification cracking in the fusion welding process and reduces the toughness of steel. … The macroscopic cross-sectional observations of the FSW joints revealed crack-free structures even in steel containing 0.3 mass% P. …

    Tetsu-to-Hagane 106(12), 892-901, 2020

    J-STAGE 

  • Simulations of Non-Equilibrium and Equilibrium Segregation in Nickel-Based Superalloy Using Modified Scheil-Gulliver and Phase-Field Methods

    Okugawa Masayuki , Izumikawa Daichi , Koizumi Yuichiro

    … In the present study, we have investigated (i) non-equilibrium segregation in solidification, and (ii) equilibrium segregation at grain boundary in Ni-based Hastelloy-X (HX) superalloy using the modified Scheil-Gulliver model (i.e., Scheil-Gulliver model with back diffusion) and a phase-field model. … This finding opens new way of controlling materials properties which are dominated by the nature of grain boundaries such as corrosion resistance, crack sensitivity, high temperature strength.</p> …

    MATERIALS TRANSACTIONS 61(11), 2072-2078, 2020

    J-STAGE 

  • STABILITY OF CAISSON-TYPE QUAY WALL AGAINST TSUNAMI UNDERTOW  [in Japanese]

    TSURUTA Naoki , SUZUKI Kojiro , ASAHI Shota , TOOYAMA Kenji

    <p> ケーソン型岸壁の耐津波性能について,ケーソンに作用する波力や引き波によるケーソン背後の裏込部の影響に関する検討は未だ不十分な状況にある.そこで本研究では,水理模型実験を実施して,岸壁のケーソンに作用する津波の越流波力の変動特性と波力算定式のための静水圧補正係数を整理した.また,堤体の安定性向上の手段として,裏込部の固化処理による効果を確認するとともに,周囲構造物の損傷(固化処理 …

    Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) 76(2), I_144-I_149, 2020

    J-STAGE 

  • Initially Solidified Shell Growth of Hypo-peritectic Carbon Steel in Continuous Casting Mold

    Mizukami Hideo , Shirai Yoshihisa , Hiraki Sei

    <p>The occurrence of longitudinal surface cracks in hypo-peritectic carbon steel slabs depends largely on the cooling capacity of the mold and the flow velocity of molten steel below the meniscu …

    ISIJ International 60(9), 1968-1977, 2020

    J-STAGE 

  • Investigation of Prediction Method for Crack and Deformation of Cemented Carbide Cast-in Insertion Multi-Component White Cast Irons by Thermal Stress Analysis  [in Japanese]

    Murase Shigeya , Shimizu Kazumichi , Kusumoto Kenta , Matsumoto Hiroki , Osafune Yasuhiro , Purba Riki Hendra

    … However, some of cemented carbide cast-in insertion specimens were found to crack or deform after solidification. … Thus, in this study, we conducted thermal stress analysis using the finite element method, and established a prediction method for the cracks and deformations of cemented carbide cast-in insertion multi-component white cast irons after solidification. …

    Journal of Japan Foundry Engineering Society 92(7), 339-344, 2020

    J-STAGE 

  • Influence of Pouring Temperature on Microstructure and Elevated Temperature Properties of Heat Resistant Cast Steel  [in Japanese]

    Luan Ngo Huynh Kinh , Koizumi Koreaki , Sawada Kazunori , Mizuno Kuniaki , Okuyama Tetsuya

    … This can be explained by the crystallization behavior of primary carbides after solidification in terms of their morphology, amount as well as thermal stabilization. … The effects of secondary carbides on the suppression of crack propagation emitted under thermal shock and / or creep environment were smaller than primary carbides. …

    Journal of Japan Foundry Engineering Society 92(7), 351-359, 2020

    J-STAGE 

  • Hot Cracking Susceptibility and Solidification Segregation Analysis by Computer Simulation in Duplex Stainless Steels  [in Japanese]

    KIM Dong Cho , OGURA Tomo , TANABE Yoshihiro , YAMASHITA Shotaro , SAIDA Kazuyoshi

    Solidification cracking susceptibility in arc & laser welding of DSSs (duplex stainless steels) was quantitatively evaluated and the numerical simulation of solidification cracking susceptibility has clarified the affecting factors. … The solidification cracking susceptibilities of DSSs were lower than those of austenitic SSs with A mode solidification modes. …

    QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 38(2), 76-84, 2020

    J-STAGE 

  • Behavior of Crack Generation of Slag in Continuous Solidification Process of Blast Furnace Slag  [in Japanese]

    Ta Yasutaka , Hoshino Takeru , Tobo Hiroyuki , Watanabe Keiji , Takahashi Katsunori

    … <p>A continuous solidification process of blast furnace slag was developed to promote the use of air-cooled slag coarse aggregate for concrete. … Therefore, microscopic observation and thermal stress analysis of the solidified slag were carried out to clarify the mechanism of crack generation in the plate-like slag. …

    Tetsu-to-Hagane 106(5), 281-289, 2020

    J-STAGE 

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