Papers - Komotori, Jun

Effect of Room Temperature Fine Particle Peening Pretreatment on Grain Refinement of Fe–Cr Alloys by AIH-FPP

Takesue S., Kikuchi S., Komotori J.

Materials Transactions (Materials Transactions)  63 ( 2 ) 203 - 208 2022

ISSN  13459678

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Fine particle peening (FPP) at room temperature was introduced to create finer grains at the surfaces of Fe–Cr alloys that were then treated by atmospheric controlled induction heating FPP (AIH-FPP). The effect of the proposed treatment on the grain refinement behavior of the alloys was investigated using optical microscopy and micro-Vickers hardness testing. The FPP pretreatment at room temperature increased the effectiveness of the grain refinement via dynamic recrystallization during subsequent AIH-FPP. Grain refinement at the surface of Fe–Cr alloys progressed with an increase in the cycles of the treatment. The addition of Cr in Fe–Cr alloys promotes the formation of fine grains during the treatment. Specimens with fine grains created via static recrystallization were also prepared and compared to grains formed via dynamic recrystallization by the room temperature FPP pretreatment and subsequent AIH-FPP to evaluate the effectiveness of the proposed treatment. The grains formed through dynamic recrystallization by the proposed treatment were finer than those formed through static recrystallization. These results indicate that the proposed combination of room temperature FPP and AIH-FPP is effective for the formation of fine grains at the surfaces of Fe–Cr alloys.

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Surface modification of titanium alloy via atmospheric pressure nitrogen plasma assisted femtosecond laser irradiation

K.Katahira, A. Ezura, S.Takeue, J.Komotori

CIRP Annals – Manufacturing, 71   469 - 472 2022

Accepted

Effect of atmospheric-controlled induction-heating fine particle peening on wear resistance and fatigue properties of maraging steel fabricated by laser powder-bed fusion

S. Takesue, A. Ezura, Y. Maki, M. Hayama, Y. Misaka, J. Komotori

ournal of Materials Research and Technology (Journal of Materials Research and Technology)  21   373 - 387 2022

Accepted,  ISSN  22387854

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Maraging steel components fabricated by laser powder-bed fusion, which is a technique of additive manufacturing, are expected to be used widely because of their high strength, hardness and toughness. To apply maraging steel manufactured by laser powder-bed fusion in wider industrial fields and prevent the components from fracture, a study was conducted to improve the wear resistance and fatigue properties of the steel by an atmospheric-controlled induction-heating fine particle peening surface modification technique. The technique developed can create hard intermetallic compound layers and introduce peening effects, which are expected to improve the wear resistance and fatigue properties of maraging steel fabricated by laser powder-bed fusion. The prepared specimens were examined using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, laser microscopy, X-ray diffraction, micro-Vickers hardness testing, nano-indentation testing, reciprocating ball-on-disk wear tests and axial fatigue tests. It was revealed that atmospheric-controlled induction-heating fine particle peening using mechanically milled particles formed Fe-Al intermetallic compound layers with high hardness, introduced compressive residual stresses and increased the hardness of the maraging steel substrate owing to age hardening. In conclusion, atmospheric-controlled induction-heating fine particle peening can simultaneously improve the wear resistance and fatigue properties of maraging steel fabricated by laser powder-bed fusion within a few minutes. These achievements can expand applications of maraging steel fabricated by laser powder-bed fusion.

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Change Behavior of Retained Austenite and Residual Stress on Carburized SCM420H Steel during Fatigue Process

羽山元晶，牧悠介， 菊池将一，小茂鳥潤

鉄と鋼 108 ( 11 ) 891 - 899 2022

Last author

Development of accurate temperature regulation culture system with metallic culture vessel demonstrates different thermal cytotoxicity in cancer and normal cells

C.Imashiro, H.Takeshita, T.Morikura, S.Miyata, K.Takemura, J.Komotori

Scientific Reports (Scientific Reports)  11 ( 21466 )  2021.11

Accepted

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Hyperthermia has been studied as a noninvasive cancer treatment. Cancer cells show stronger thermal cytotoxicity than normal cells, which is exploited in hyperthermia. However, the absence of methods evaluating the thermal cytotoxicity in cells prevents the development of hyperthermia. To investigate the thermal cytotoxicity, culture temperature should be regulated. We, thus, developed a culture system regulating culture temperature immediately and accurately by employing metallic culture vessels. Michigan Cancer Foundation-7 cells and normal human dermal fibroblasts were used for models of cancer and normal cells. The findings showed cancer cells showed stronger thermal cytotoxicity than normal cells, which is quantitatively different from previous reports. This difference might be due to regulated culture temperature. The thermal stimulus condition (43 °C/30 min) was, further, focused for assays. The mRNA expression involving apoptosis changed dramatically in cancer cells, indicating the strong apoptotic trend. In contrast, the mRNA expression of heat shock protein (HSP) of normal cells upon the thermal stimulus was stronger than cancer cells. Furthermore, exclusively in normal cells, HSP localization to nucleus was confirmed. These movement of HSP confer thermotolerance to cells, which is consistent with the different thermal cytotoxicity between cancer and normal cells. In summary, our developed system can be used to develop hyperthermia treatment.

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Effects of particle collision treatments on fatigue strength of Ti-6Al-4V alloy with polishing marks

T.Morita, A.Miyatani, S.Takesue, M.Kumagai, J.Komotori

Materials Transactions (Zairyo/Journal of the Society of Materials Science, Japan)  62 ( 9 ) 1298 - 1303 2021.09

Accepted,  ISSN  05145163

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In this study, we attempted to nullify the harmful influences of processing marks on the fatigue strength of Ti-6Al-4V alloy by particle collision treatments. As the surface treatments, fine particle bombarding (FPB) and shot peening (SP) were applied to form hardened layers and introduce compressive residual stress. The surface of the objective material was polished to a mirror surface to eliminate the influences of machining on specimens and was then grinded with emery papers (#80) to make uniform processing marks. After the particle collision treatments, the surface conditions, hardness distributions and residual stress were systematically examined, and their relationships with the fatigue strength were considered in detail. On observation of the surfaces, the processing marks were eliminated by the particle collision treatments. At the same time, the surface hardness was increased and high compressive residual stress was introduced. As a result, the fatigue strength was markedly improved by the treatments beyond the level of the material with the processing marks without deterioration of the mechanical properties. The improvement rates of the fatigue strength were high, at 75% by FPB treatment and 58% by SP treatment.

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細胞の熱耐性の検討に資する温度制御可能なチタン製培養装置の開発

今城哉裕，井田雄太，宮田昌悟，小茂鳥潤

材料 70 ( 6 ) 479 - 485 2021.06

Accepted

Formation of Fe-Al intermetallic compound layer by AIH-FPP and its effect on tribological properties of stainless steel

Shogo TAKESUE, Yoshitaka MISAKA, Jun KOMOTORI

ISIJ International (ISIJ International)  61 ( 6 ) 1946 - 1954 2021.06

Accepted,  ISSN  09151559

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In order to increase the surface hardness and improve the tribological properties of stainless steel, Fe–Al intermetallic compound layers were created by atmospheric-controlled induction-heating fine particle peening (AIH-FPP). The surface microstructure of the stainless steel treated with AIH-FPP was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and micro-Vickers hardness testing. In addition, the tribological properties were investigated by reciprocating ball-on-disk wear tests. When high-speed steel particles coated with thin aluminum layers were used as the shot particles, Fe–Al intermetallic compound layers were formed at the surfaces of the stainless steel with increased heating time during AIH-FPP. This is because aluminum was transferred from the shot particles, and the temperature at the treated surface increased as a result of a combustion synthesis reaction. When the heating temperature after FPP was increased, the transferred aluminum and nitrogen in the atmosphere reacted, which resulted in the formation of aluminum nitrides in addition to Fe–Al intermetallic compounds. The tribological properties of the stainless steel were improved by AIH-FPP since high-hardness layers were created. The results indicate that the formation of an Fe–Al intermetallic compound layer with high hardness by AIH-FPP is effective for modifying the tribological properties of the stainless steel within a relatively short span of time.

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Rapid oxynitriding of Ti-6Al-4V alloy by induction heating in air

Kazuki Tamura, Shogo Takesue, Tatsuro Morita, Elia Marin, Jun Komotori, Yoshitaka Misaka, Masao Kumagai

Materials Transactions (Materials Transactions)  62 ( 1 ) 111 - 117 2021

Accepted,  ISSN  13459678

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In this study, a rapid oxynitriding technique based on induction-heating was developed for the titanium alloy Ti6Al4V, and its effects on surface characteristics of the alloy were investigated. The surface microstructures of the alloy were characterized by employing a scanning electron microscope, electron back-scatter diffraction, X-ray diffraction and nano-indentation tests. Induction-heating in air for 60 s caused the formation of a hardened layer on the Ti6Al4V alloy surface, which can be attributed to the diffusion of oxygen and nitrogen atoms. When water quenching was performed after heating, transformation to an acicular martensitic ¡A phase occurred, resulting in increased in substrate hardness. However, cracks were initiated at the surface of the oxynitrided alloy. The cracks were eliminated through fine particle bombarding treatment, whereas the hardened layer formed by the oxynitriding treatment remained. The obtained results thus indicate that the oxynitriding technique developed in this study can enhance the wear resistance and tensile strength of the Ti6Al4V alloy within a short period of time.

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Evaluation of the Compressive Residual Stress Relaxation Behavior by in situ X-ray Stress Measurement

羽山元晶，菊池将一，小茂鳥潤

鉄と鋼 107 ( 2 ) 137 - 145 2021

Accepted

Combined effect of gas blow induction heating nitriding and post-treatment with fine particle peening on surface properties and wear resistance of titanium alloy

S.Takesue, S.Kikuchi, Y.Misaka, T.Morita, J.Komotori

Materials Transactions (Materials Transactions)  62 ( 10 ) 1502 - 1509 2021

Accepted,  ISSN  13459678

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In order to fabricate a titanium alloy with superior wear resistance and fatigue strength, fine particle peening (FPP) was introduced as a post-treatment after gas blow induction heating (GBIH) nitriding. The surface characteristics of the treated alloy were examined using X-ray diffraction, scanning electron microscopy, laser microscopy and a micro-Vickers hardness tester. GBIH nitriding and post-treatment with FPP formed nitrided layers with high hardness and compressive residual stress at the surface of the alloy within a short period of time. This is due to the diffusion of nitrogen atoms during GBIH nitriding and plastic deformation of the surface layer during FPP. Reciprocating ball-on-disk wear tests were performed to investigate the wear resistance of the surface-treated alloy. The wear resistance of the titanium alloy was improved by the proposed surface treatment compared with samples that were only polished or FPP-treated. This is due to the presence of a nitrogen compound layer with high hardness at the surface. The abrasiveness toward the wear test counter material was also decreased by the combined surface treatment.

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研磨痕を有するTi-6Al-4V合金の疲労強度に及ぼす粒子衝突処理の効果

森田辰郎，宮谷厚志，武末翔吾，熊谷正夫，小茂鳥潤

材料 69 ( 12 ) 915 - 920 2020.12

Accepted

Rapid nitriding mechanism of titanium alloy by gas blow induction heating

S. Takesue, S．Kikuchi，Y．Misaka，T．Morita，J．Komotori

Surface and Coatings Technology (Surface and Coatings Technology)  399 2020.10

Joint Work, Accepted,  ISSN  02578972

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This work characterized the surface-modified layers generated on a titanium alloy during gas blow induction heating (GBIH), so as to elucidate the rapid nitriding mechanism. The surface microstructures of GBIH nitrided specimens were analyzed by X-ray diffraction, micro-Vickers hardness testing, scanning electron microscopy and X-ray photoelectron spectroscopy. The data indicate that applying this process for only several minutes can forms nitrided layers on Ti-6Al-4V alloy surfaces, the characteristics of which are similar to those of layers produced by ordinary gas nitriding for several hours. The temperature inside the material was determined to be higher than that on the surface during GBIH nitriding. However, the thickness of the nitrided layer exceeded the estimated value based on the diffusion coefficient at this high internal temperature. This especially thick nitrided layer can possibly be attributed to eddy currents generated in the metal by the application of a high-frequency current. Passivation films on the surface of the Ti-6Al-4V alloy were found to be removed during GBIH nitriding, which is ascribed to the diffusion of oxygen atoms in the passivation film into the substrate. Thus, the data show that GBIH nitriding is able to modify a Ti-6Al-4V alloy within a short period of time based on the effect of an eddy current and the disappearance of the passivation film.

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Rapid oxynitriding of Ti-6Al-4V alloy by induction heating in air

Tamura K., Takesue S., Morita T., Marin E., Komotori J., Misaka Y., Kumagai M.

Zairyo/Journal of the Society of Materials Science, Japan (Zairyo/Journal of the Society of Materials Science, Japan)  69 ( 8 ) 605 - 611 2020.08

ISSN  05145163

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© 2020 Society of Materials Science Japan. All rights reserved. In this study, a rapid oxynitriding technique based on induction heating was developed for the titanium alloy Ti-6Al-4V, and its effects on surface characteristics of the alloy were investigated. The surface microstructures of the alloy were characterized by employing a scanning electron microscope, electron back-scatter diffraction, X-ray diffraction and nano-indentation tests. Induction-heating in air for 60 s caused the formation of a hardened layer on the Ti-6Al-4V alloy surface, which can be attributed to the diffusion of oxygen and nitrogen atoms. When water quenching was performed after heating, transformation to an acicular martensitic α’ phase occurred, resulting in increased in substrate hardness. However, cracks were initiated at the surface of the oxynitrided alloy. The cracks were eliminated through fine particle bombarding treatment, whereas the hardened layer formed by the oxynitriding treatment remained. The obtained results thus indicate that the oxynitriding technique developed in this study can enhance the wear resistance and tensile strength of the Ti-6Al-4V alloy within a short period of time.

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AIH-FPPシステムを用いた投射粒子成分の移着と拡散による金属間化合物の創成

武末翔吾，渡邊一敬，三阪佳孝，小茂鳥潤

砥粒加工学会誌 64 ( 8 ) 421 - 427 2020.08

Influences of particle collision treatments on surface characteristics and fatigue strength of Ti-6Al-4V alloy

T. Morita, A. Miyatani, S. Kariya, M. Kumagai, S. Takesue, J. Komotori

Results in Materials (Results in Materials)  7 2020.08

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In this study, the particle collision treatments (fine particle bombarding (FPB) and conventional shot peening (SP)) were performed for Ti–6Al–4V alloy in order to comprehensively investigate the influences of their treatment conditions on the surface conditions, microstructures, hardness distributions and residual stress. Moreover, we examined the relationship between the surface characteristics of the treated materials and their mechanical properties including fatigue strength in detail. According to the obtained experimental results, the values of the maximum height waviness increased with increasing in the size of collision particles and injection pressure. Among all the treated materials, the differences in hardness distribution were relatively small because the work hardening exponent of Ti–6Al–4V alloy is low and the degree of work hardening is insensitive to the amount of plastic deformation. The absolute values of compressive residual stress generated at the surfaces became higher when finer particles were used as collision particles. The increase in injection pressure increased the surface temperature and released the introduced residual stress. As the particle collision treatments affected only the surface regions, the mechanical properties of the treated materials were almost the same as those of the annealed one. In the range of the conditions examined in this study, the most effective treatment to improve the fatigue strength of Ti–6Al–4V alloy was FPB under a relatively low injection pressure. This was because the value of the maximum height waviness was the smallest and the highest compressive residual stress was introduced at the same time.

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Characterization of surface layer formed by gas blow induction heating nitriding at different temperatures and its effect on the fatigue properties of titanium alloy

S. Takesue, S. Kikuchi, H. Akebono, T. Morita, J. Komotori

Results in Materials (Results in Materials)  5 2020

Research paper (scientific journal), Joint Work

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Gas blow induction heating (GBIH) nitriding was carried out for Ti–6Al–4V alloy at different temperatures, and its effect on surface characteristics, wear resistance and fatigue properties was investigated. The microstructures of the specimen surface were characterized using optical microscopy, laser microscopy, X-ray diffraction, micro-Vickers hardness tester, and nano-indentation tester. It was found that the surface characteristics of titanium alloy varied with increasing the treatment temperature of GBIH-nitriding. In this study, a nitrogen diffusion layer was formed on the titanium alloy surface GBIH-nitrided at 1073 ​K. A nitrogen compound layer and diffusion layer were created at the treatment temperature of 1173 ​K, which suppressed the wear loss to under one tenth that of the substrate. In order to examine the fatigue properties of the treated alloy, fatigue tests under four-point bending were performed. The fatigue strength of the Ti–6Al–4V alloy GBIH-nitrided at 1173 ​K was 234 ​MPa lower than that of the mirror-polished alloy. The decrease in the fatigue strength is due to the formation of the compound layer with a Young's modulus approximately twice that of the substrate, and the grain coarsening from 7 ​μm to 300 ​μm. The results indicate that a thick nitrided layer with high hardness and the close Young's modulus to the substrate improved the fatigue strength of the Ti–6Al–4V alloy.

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Generation of Biocompatible Titanium Alloy Surfaces Including Calcium and Phosphorus Elements by Laser-Induced Mist Spraying Wet Treatment

A. Ezura, K. Katahira, J. Komotori

Int. J. of Automation Technology (International Journal of Automation Technology)  14 ( 4 ) 575 - 581 2020

ISSN  18817629

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© 2020, Fuji Technology Press. All rights reserved. Titanium alloys are widely used for the hard tissue substitute implants. However, it is necessary to improve interfacial biocompatibility to reduce adhesion period. For improvement of biocompatibility of Ti-6Al-4V ELI alloys, texture and chemical composition on contact part with biological tissue play very important roles. In this research, micro texture was generated on the Ti-6Al-4V ELI alloy surfaces utilizing laser irradiation, in order to improve biocompatibility. The biocompatibility was evaluated by osteoblast cell culture assays. The results indicated the surface having micro texture improve biocompatibility as com-pared with untreated surface. This was considered in order the fact that the formed modified surface had hydrophilicity, thereby improving the cell compatibility, and the cell adhesion due to the complicated shape. In addition, mist of glycerophosphoric acid calcium aqueous solution was applied on the laser irradiated area. As result, micro texture including Ca and P elements was generated on the Ti-6Al-4V ELI alloy surfaces. When laser was irradiated, glycerophosphoric acid calcium aqueous solution was applied as mist flowed on the test pieces as droplet. The velocity of droplet fluid was relatively fast, so that laser irradiation was unhindered access to the surface of test pieces and the treatment was stable. In order to estimate biocompatibility, culture assays using osteoblast cells were conducted on the treated surface having micro texture including Ca and P elements. As results, it was clearly that biocompatibility of the specimen treated by laser with glycerophosphoric acid calcium aqueous solution mist more improved than either untreated specimen or treated specimen soaked in glycerophos-phoric acid calcium aqueous solution.

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大気中での高周波誘導加熱によるTi-6Al-4V合金の高速酸窒化処理

田村和暉，武末翔吾， 森田辰郎，Elia Marin， 小茂鳥潤，三阪佳孝， 熊谷正夫

材料 69 ( 8 ) 605 - 611 2020

Generation of micro texture including calcium and phosphorus elements on titanium alloy for improvement of biocompatibility with laser induced mist surface treatment

Ezura A., Katahira K., Komotori J.

JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing, LEMP 2020 (JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing, LEMP 2020)   2020

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Titanium alloys are widely used for the hard tissue substitute implants. However, it is necessary to improve interfacial biocompatibility for reduce adhesion period. For improvement of biocompatibility of titanium alloys, texture and chemical composition on contact part with biological tissue play very important roles. In this research, mist of glycerophosphoric acid calcium aqueous solution was applied on the laser irradiated area. As result, micro texture including Ca and P elements was generated on the Ti-6Al-4V-ELI alloys surfaces. When laser was irradiated, glycerophosphoric acid calcium aqueous solution applied as mist flowed on the test pieces as droplet. The velocity of droplet fluid was relatively fast, so that laser irradiation was unhindered access to the surface of specimens and the treatment was stable. In order to estimate biocompatibility of treated surfaces having micro texture with Ca and P element, culture assays using osteoblast cells were conducted. As result, it was clearly that biocompatibility of the specimen treated by laser with glycerophosphoric acid calcium aqueous solution mist more improved than treated specimen soaked in glycerophosphoric acid calcium aqueous solution.

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