Pub Date : 2021-03-01DOI: 10.2320/JINSTMET.J2020049
K. Imamura, A. Nishimoto
In order to investigate the e ff ect of the screen hole state of the active screen plasma nitriding ( ASPN ) process using Ti screen, low carbon steel S15C was treated by ASPN treatment and DC plasma nitriding treatment ( S – DCPN ) using the Ti screen with the hole diameter of ϕ 5mm, 10mm, and 20mm and the open area ratio of 0 ％ , 15 ％ , 35 ％ , and 55 ％ . Plasma nitriding was performed at 873K for 180min at a gas pressure of 300Pa under an atmosphere of 75 ％ N 2 + 25 ％ H 2 . After the nitriding treatment, X – ray di ff raction ( XRD ) , surface microstructure observation, cross – section microstructure observation, wear test, Vickers hardness test, glow discharge optical emission spectrometry ( GD – OES ) , and corrosion test were performed. As a result, the wear resistance of the ASPN – treated samples was improved under the condition that the deposit particles were small and the deposit layer was thick. In the cross – sectional microstructure of the S – DCPN – treated samples, a compound layer composed of iron nitrides and a di ff usion layer in which γ ’ – Fe 4 N was precipitated by nitrogen di ff usion were con fi rmed. The surface compound layer of iron nitrides was not formed when a screen with a hole size of 20mm and open area ratio of 55 ％ was used. The results of SEM – EDX also con fi rmed the di ff usion of titanium by S – DCPN treatment using a Ti screen. ［ doi:10.2320 / jinstmet.J2020049 ］ ( Received October 14, 2020; Accepted November 18, 2020; Published January 22, 2021 )
{"title":"Effect of Screen Open Hole on Nitriding Behavior, Corrosion Resistance and Wear Resistance of Plasma Nitrided Low Carbon Steel Using Ti Screen","authors":"K. Imamura, A. Nishimoto","doi":"10.2320/JINSTMET.J2020049","DOIUrl":"https://doi.org/10.2320/JINSTMET.J2020049","url":null,"abstract":"In order to investigate the e ff ect of the screen hole state of the active screen plasma nitriding ( ASPN ) process using Ti screen, low carbon steel S15C was treated by ASPN treatment and DC plasma nitriding treatment ( S – DCPN ) using the Ti screen with the hole diameter of ϕ 5mm, 10mm, and 20mm and the open area ratio of 0 ％ , 15 ％ , 35 ％ , and 55 ％ . Plasma nitriding was performed at 873K for 180min at a gas pressure of 300Pa under an atmosphere of 75 ％ N 2 + 25 ％ H 2 . After the nitriding treatment, X – ray di ff raction ( XRD ) , surface microstructure observation, cross – section microstructure observation, wear test, Vickers hardness test, glow discharge optical emission spectrometry ( GD – OES ) , and corrosion test were performed. As a result, the wear resistance of the ASPN – treated samples was improved under the condition that the deposit particles were small and the deposit layer was thick. In the cross – sectional microstructure of the S – DCPN – treated samples, a compound layer composed of iron nitrides and a di ff usion layer in which γ ’ – Fe 4 N was precipitated by nitrogen di ff usion were con fi rmed. The surface compound layer of iron nitrides was not formed when a screen with a hole size of 20mm and open area ratio of 55 ％ was used. The results of SEM – EDX also con fi rmed the di ff usion of titanium by S – DCPN treatment using a Ti screen. ［ doi:10.2320 / jinstmet.J2020049 ］ ( Received October 14, 2020; Accepted November 18, 2020; Published January 22, 2021 )","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86306232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-01DOI: 10.2320/MATERTRANS.MT-M2021009
J. Kubo, Yuichiro Koizumi, Takuya Ishimoto, T. Nakano
Metal additive manufacturing ( AM ) technologies are attracting attentions not only as a forming process but also as microstructure controlling processes. In powder bed fusion ( PBF ) AM, crystal orientations can be controlled by scanning strategies of energy beam. To optimize microstructures, computer simulations for predicting microstructures play very important roles. In this work, we have developed simulation programs to explain the mechanism of the crystal orientation control. First, we simulated the shape of melt pool by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections. It was assumed that the primary crystal growth direction can be determined by the temperature gradient, and the crystals grow keeping the growth direction as generally recognized. The shapes of simulated melt pools agree well with experimental observations. The modi fi ed cellular automaton simulations successfully reproduced two typical textures with di ff erent preferential orientations along the building directions of 〈 001 〉 and 〈 011 〉 when the bidirectional scanning with and without a rotation of 90° was accomplished between the layers. ［ doi:10.2320 / jinstmet.J2020028 ］
{"title":"Modified Cellular Automaton Simulation of Metal Additive Manufacturing","authors":"J. Kubo, Yuichiro Koizumi, Takuya Ishimoto, T. Nakano","doi":"10.2320/MATERTRANS.MT-M2021009","DOIUrl":"https://doi.org/10.2320/MATERTRANS.MT-M2021009","url":null,"abstract":"Metal additive manufacturing ( AM ) technologies are attracting attentions not only as a forming process but also as microstructure controlling processes. In powder bed fusion ( PBF ) AM, crystal orientations can be controlled by scanning strategies of energy beam. To optimize microstructures, computer simulations for predicting microstructures play very important roles. In this work, we have developed simulation programs to explain the mechanism of the crystal orientation control. First, we simulated the shape of melt pool by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections. It was assumed that the primary crystal growth direction can be determined by the temperature gradient, and the crystals grow keeping the growth direction as generally recognized. The shapes of simulated melt pools agree well with experimental observations. The modi fi ed cellular automaton simulations successfully reproduced two typical textures with di ff erent preferential orientations along the building directions of 〈 001 〉 and 〈 011 〉 when the bidirectional scanning with and without a rotation of 90° was accomplished between the layers. ［ doi:10.2320 / jinstmet.J2020028 ］","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72724349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-01DOI: 10.2320/JINSTMET.J2020055
H. Fukuoka, Xinsheng Huang, Kazutaka Suzuki, Yuhki Tsukada, T. Koyama, Y. Chino
E ff ect of rolling temperature on room temperature formability and texture formation of Mg – 3mass ％ Al – 1mass ％ Sn ( AT31 ) alloy sheet was investigated, and compared with the results of Mg – 3mass ％ Al – 1mass ％ Zn ( AZ31 ) alloy sheet. When the rolling temperature was set to a high temperature ( 798K ) , AT31 alloy showed almost the same basal texture intensity as AZ31 alloy rolled at the same condition. When the rolling temperature was set to a low temperature ( 723K ) , AT31 alloy showed lower basal texture intensity than AZ31 alloy rolled at the same condition. As a result of Erichsen test, when the rolling temperature was set to 798K, AT31 alloy exhibited excellent Erichsen value more than 8.8mm, which corresponded to AZ31 alloy rolled at the same condition. On the other hand, when the rolling temperature was set to 723K, AT31 alloy exhibited higher Erichsen value ( 6.7mm ) than that of AZ31 alloy ( 4.5mm ) . The variations in Erichsen values with di ff erences in alloy composition and rolling temperature were closely related to the variations in basal texture intensity. Recrystallization behavior of AT31 alloy during the initial stage of the fi nal annealing was investigated. It is found that recrystallization mainly occurred at grain boundaries, and grains with more random orientation were recrystallized, when the rolling temperature was set to 798K. Mechanisms of recrystallization and random texture formation were almost the same with those of AZ31 alloy. The reason why AT31 alloy rolled at 723K exhibited more random texture than AZ31 rolled at the same condition is that grains with more random orientation were recrystallized at grain boundaries during the fi nal annealing.
研究了轧制温度对Mg - 3mass % Al - 1mass % Sn (AT31)合金板材室温成形性能和织构形成的影响，并与Mg - 3mass % Al - 1mass % Zn (AZ31)合金板材的结果进行了比较。当轧制温度为798K时，AT31合金的基态织构强度与相同轧制温度下的AZ31合金基本相同。当轧制温度设置为较低(723K)时，AT31合金的基底织构强度低于相同轧制温度下的AZ31合金。Erichsen试验结果表明，当轧制温度为798K时，AT31合金的Erichsen值大于8.8mm，与相同条件下轧制的AZ31合金的Erichsen值相当。另一方面，当轧制温度为723K时，AT31合金的Erichsen值(6.7mm)高于AZ31合金(4.5mm)。Erichsen值随合金成分和轧制温度差异的变化与基体织构强度的变化密切相关。研究了AT31合金在最后退火初期的再结晶行为。结果表明，当轧制温度为798K时，再结晶主要发生在晶界处，晶粒取向更加随机。再结晶和随机织构的形成机制与AZ31合金基本相同。在723K下轧制的AT31合金比在相同条件下轧制的AZ31合金表现出更随机的织构，其原因是在最后退火过程中晶界处发生了更随机取向的晶粒再结晶。
{"title":"Effect of Rolling Temperature on Room Temperature Formability and Texture Formation of Mg-3 mass％Al-1 mass％Sn Alloy Sheet","authors":"H. Fukuoka, Xinsheng Huang, Kazutaka Suzuki, Yuhki Tsukada, T. Koyama, Y. Chino","doi":"10.2320/JINSTMET.J2020055","DOIUrl":"https://doi.org/10.2320/JINSTMET.J2020055","url":null,"abstract":"E ff ect of rolling temperature on room temperature formability and texture formation of Mg – 3mass ％ Al – 1mass ％ Sn ( AT31 ) alloy sheet was investigated, and compared with the results of Mg – 3mass ％ Al – 1mass ％ Zn ( AZ31 ) alloy sheet. When the rolling temperature was set to a high temperature ( 798K ) , AT31 alloy showed almost the same basal texture intensity as AZ31 alloy rolled at the same condition. When the rolling temperature was set to a low temperature ( 723K ) , AT31 alloy showed lower basal texture intensity than AZ31 alloy rolled at the same condition. As a result of Erichsen test, when the rolling temperature was set to 798K, AT31 alloy exhibited excellent Erichsen value more than 8.8mm, which corresponded to AZ31 alloy rolled at the same condition. On the other hand, when the rolling temperature was set to 723K, AT31 alloy exhibited higher Erichsen value ( 6.7mm ) than that of AZ31 alloy ( 4.5mm ) . The variations in Erichsen values with di ff erences in alloy composition and rolling temperature were closely related to the variations in basal texture intensity. Recrystallization behavior of AT31 alloy during the initial stage of the fi nal annealing was investigated. It is found that recrystallization mainly occurred at grain boundaries, and grains with more random orientation were recrystallized, when the rolling temperature was set to 798K. Mechanisms of recrystallization and random texture formation were almost the same with those of AZ31 alloy. The reason why AT31 alloy rolled at 723K exhibited more random texture than AZ31 rolled at the same condition is that grains with more random orientation were recrystallized at grain boundaries during the fi nal annealing.","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76586758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.2320/matertrans.mt-m2020261
Yukio Kobayashi, A. Nishimoto
In this study, multilayer diamond-like carbon fi lms 1µm thick with di ff erent numbers of multilayer repetitions were deposited onto austenitic stainless steel SUS304 substrates using di ff erent source gases. The in fl uence of the gas and the di ff erence in the number of multilayer repetitions on the adhesion strength and wear resistance of the fi lms was subsequently investigated. The samples were subjected to cross- sectional microstructure observations, elemental analysis by glow-discharge optical emission spectroscopy, nano-indentation tests, Rockwell indentation tests, friction and wear tests, and delamination tests. The nano-indentation tests showed that the fi lms prepared using C 2 H 2 gas were harder than those prepared using CH 4 gas. In addition, irrespective of the gas used, the fi lm hardness was improved when four layers rather than two layers were deposited. However, the hardness of the eight layers fi lm decreased. The Rockwell indentation tests showed no improvement in adhesiveness when the gas or the number of multilayer repetitions was varied. The wear tests revealed that the friction coe ffi cient of the fi lms prepared using C 2 H 2 gas was smaller than that of fi lms prepared using CH 4 gas. No di ff erence was observed with increasing number of multilayer repetitions. The delamination tests showed that the distance until delamination of the fi lms prepared using C 2 H 2 gas was longer than that of the fi lms prepared using CH 4 gas. In addition, the distance until delamination was improved by changing the number of multilayer repetitions from two layers to four layers for both gases but decreased when the number of repetitions was extended to eight layers. In this study, the value of H / E (hardness / Young ’ s modulus) increased and various characteristics improved with increasing number of multilayer repetitions. [doi:10.2320 matertrans.MT-M2020261]
{"title":"Comparative Investigation of the Mechanical and Wear Properties of Multilayer Si-DLC/DLC Films","authors":"Yukio Kobayashi, A. Nishimoto","doi":"10.2320/matertrans.mt-m2020261","DOIUrl":"https://doi.org/10.2320/matertrans.mt-m2020261","url":null,"abstract":"In this study, multilayer diamond-like carbon fi lms 1µm thick with di ff erent numbers of multilayer repetitions were deposited onto austenitic stainless steel SUS304 substrates using di ff erent source gases. The in fl uence of the gas and the di ff erence in the number of multilayer repetitions on the adhesion strength and wear resistance of the fi lms was subsequently investigated. The samples were subjected to cross- sectional microstructure observations, elemental analysis by glow-discharge optical emission spectroscopy, nano-indentation tests, Rockwell indentation tests, friction and wear tests, and delamination tests. The nano-indentation tests showed that the fi lms prepared using C 2 H 2 gas were harder than those prepared using CH 4 gas. In addition, irrespective of the gas used, the fi lm hardness was improved when four layers rather than two layers were deposited. However, the hardness of the eight layers fi lm decreased. The Rockwell indentation tests showed no improvement in adhesiveness when the gas or the number of multilayer repetitions was varied. The wear tests revealed that the friction coe ffi cient of the fi lms prepared using C 2 H 2 gas was smaller than that of fi lms prepared using CH 4 gas. No di ff erence was observed with increasing number of multilayer repetitions. The delamination tests showed that the distance until delamination of the fi lms prepared using C 2 H 2 gas was longer than that of the fi lms prepared using CH 4 gas. In addition, the distance until delamination was improved by changing the number of multilayer repetitions from two layers to four layers for both gases but decreased when the number of repetitions was extended to eight layers. In this study, the value of H / E (hardness / Young ’ s modulus) increased and various characteristics improved with increasing number of multilayer repetitions. [doi:10.2320 matertrans.MT-M2020261]","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80763071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.2320/JINSTMET.J2020044
Y. Hangai, Mizuki Ando, Ryosuke Suzuki, M. Matsubara, T. Utsunomiya, N. Yoshikawa
In this study, three – layered porous aluminum consisting of AC4CH ( porosity: 70 ％ ) / pure aluminum ( 80 ％ ) / A6061 ( 75 ％ ) / and AC4CH ( 70 ％ ) / pure aluminum ( 70 ％ ) / A6061 ( 70 ％ ) were fabricated by a sintering and dissolution process. When plateau stress of each layer was signi fi cantly di ff erent, such as three – layered porous aluminum with varying porosities, exhibited clear multiple plateau regions corresponding to the deformation of each layer. In contrast, when plateau stress of each layer had a close value, such as three – layered porous aluminum with homogeneous porosities, exhibited no clear multiple plateau regions. ［ doi:10.2320 / jinstmet.J2020044 ］
{"title":"Compressive Properties of Three-Layered Porous Aluminum Fabricated by Spacer Method Using Dissimilar Alloy Powders","authors":"Y. Hangai, Mizuki Ando, Ryosuke Suzuki, M. Matsubara, T. Utsunomiya, N. Yoshikawa","doi":"10.2320/JINSTMET.J2020044","DOIUrl":"https://doi.org/10.2320/JINSTMET.J2020044","url":null,"abstract":"In this study, three – layered porous aluminum consisting of AC4CH ( porosity: 70 ％ ) / pure aluminum ( 80 ％ ) / A6061 ( 75 ％ ) / and AC4CH ( 70 ％ ) / pure aluminum ( 70 ％ ) / A6061 ( 70 ％ ) were fabricated by a sintering and dissolution process. When plateau stress of each layer was signi fi cantly di ff erent, such as three – layered porous aluminum with varying porosities, exhibited clear multiple plateau regions corresponding to the deformation of each layer. In contrast, when plateau stress of each layer had a close value, such as three – layered porous aluminum with homogeneous porosities, exhibited no clear multiple plateau regions. ［ doi:10.2320 / jinstmet.J2020044 ］","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86816014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.2320/jinstmet.j2020046
G. Kitahara, H. Matsuoka, T. Asada
Automobile manufacturers are accelerating adoption of spot welding of Advanced High-Strength-Steels (AHSS) sheets to reduce weight of automobile bodies. 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 di ff erence in microstructure caused by rapid cooling and solidi fi cation during spot welding. However, evaluation of the HE resistance for the spot-welds has not been established. In this study, we prepared spot-welded specimens using AHSS sheets and performed tensile shear tests with varying tensile rates under hydrogen charging to evaluate the relationship between di ff usible hydrogen content and tensile shear strength. As a result, the tensile shear strength of spot welds decreased as the amount of di ff usible hydrogen increased. The quasi-cleavage fracture surface and intergranular fracture surface were observed at the nugget and inside the crack generated at the nugget-heat a ff ected zone interface. Furthermore, as the results of crack growth behavior and hydrogen thermal desorption spectroscopy analysis, hydrogen embrittlement in spot welds can be attributed to the stress-induced di ff usion of hydrogen and the hydrogen trapped in dislocation and vacancy clusters at crack tips. [doi:10.2320 /
{"title":"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","authors":"G. Kitahara, H. Matsuoka, T. Asada","doi":"10.2320/jinstmet.j2020046","DOIUrl":"https://doi.org/10.2320/jinstmet.j2020046","url":null,"abstract":"Automobile manufacturers are accelerating adoption of spot welding of Advanced High-Strength-Steels (AHSS) sheets to reduce weight of automobile bodies. 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 di ff erence in microstructure caused by rapid cooling and solidi fi cation during spot welding. However, evaluation of the HE resistance for the spot-welds has not been established. In this study, we prepared spot-welded specimens using AHSS sheets and performed tensile shear tests with varying tensile rates under hydrogen charging to evaluate the relationship between di ff usible hydrogen content and tensile shear strength. As a result, the tensile shear strength of spot welds decreased as the amount of di ff usible hydrogen increased. The quasi-cleavage fracture surface and intergranular fracture surface were observed at the nugget and inside the crack generated at the nugget-heat a ff ected zone interface. Furthermore, as the results of crack growth behavior and hydrogen thermal desorption spectroscopy analysis, hydrogen embrittlement in spot welds can be attributed to the stress-induced di ff usion of hydrogen and the hydrogen trapped in dislocation and vacancy clusters at crack tips. [doi:10.2320 /","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80844602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.2320/JINSTMET.J2020045
H. Sato, N. Adachi, Y. Todaka
The e ff ect of one – pass strain, | ± Δε |, on grain re fi nement was systematically investigated by cyclic – HPT straining with a repetitive deformation process in which positive and negative shear strain are introduced. The steady – state grain size, d ss , depended on | ± Δε | rather than the given total strain, Σ | ± Δε |. The unstable dislocation cell walls formed by positive strain, + Δε , was discomposed by negative strain, − Δε . The stability of dislocation cell wall increased as the number of dislocations introduced by applying | ± Δε | in a grain, n , increased. The decrease in n was caused by decreasing + Δε and grain size. It was found that n a ff ected the stability of dislocation cell walls and was an important factor in determining d ss . ［ doi:10.2320 / jinstmet.J2020045 ］
{"title":"Effect of One-Pass Strain on Steady-State Grain Size by Cyclic - HPT Straining","authors":"H. Sato, N. Adachi, Y. Todaka","doi":"10.2320/JINSTMET.J2020045","DOIUrl":"https://doi.org/10.2320/JINSTMET.J2020045","url":null,"abstract":"The e ff ect of one – pass strain, | ± Δε |, on grain re fi nement was systematically investigated by cyclic – HPT straining with a repetitive deformation process in which positive and negative shear strain are introduced. The steady – state grain size, d ss , depended on | ± Δε | rather than the given total strain, Σ | ± Δε |. The unstable dislocation cell walls formed by positive strain, + Δε , was discomposed by negative strain, − Δε . The stability of dislocation cell wall increased as the number of dislocations introduced by applying | ± Δε | in a grain, n , increased. The decrease in n was caused by decreasing + Δε and grain size. It was found that n a ff ected the stability of dislocation cell walls and was an important factor in determining d ss . ［ doi:10.2320 / jinstmet.J2020045 ］","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76850940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2320/jinstmet.j2020056
F. Yamashita, Y. Soejima, H. Akamine, M. Nishida
Fumiyoshi Yamashita1,2, Yohei Soejima3, Hiroshi Akamine3 and Minoru Nishida3 1 Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816–8580 2 Technology Development Department, Special Metals Division, Furukawa Techno Material Co., Ltd., Hiratsuka 254–0016 3 Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University, Kasuga 816–8580
{"title":"Effect of Ni Concentrations and C/O Ratios on the Stability of Nonmetallic Inclusions in Ni-Rich Ti-Ni Alloys","authors":"F. Yamashita, Y. Soejima, H. Akamine, M. Nishida","doi":"10.2320/jinstmet.j2020056","DOIUrl":"https://doi.org/10.2320/jinstmet.j2020056","url":null,"abstract":"Fumiyoshi Yamashita1,2, Yohei Soejima3, Hiroshi Akamine3 and Minoru Nishida3 1 Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816–8580 2 Technology Development Department, Special Metals Division, Furukawa Techno Material Co., Ltd., Hiratsuka 254–0016 3 Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University, Kasuga 816–8580","PeriodicalId":17322,"journal":{"name":"Journal of the Japan Institute of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82670412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2320/jinstmet.j2020037
J. Goto, T. Koyama, Yuhki Tsukada
The anomalous discontinuous precipitation which is called “Cellular Decomposition (CD)” has been observed in Cu–Ni–X (X = Co,Fe) ternary systems, i.e., the precipitate morphology in cell region is a nanoscale fine fiber, the direction of the fibers does not take specific crystal orientation, and the morphology is wavy. In this study, we elucidated the reason why such an unusual cellular decomposition occurs by means of the Calphad method and phase–field simulations. In particular, we focused on the spinodal decomposition inside the grain before CD. The results showed that the Ni component preferentially segregates at the interface region between precipitate and matrix phase in the two–phase microstructure by spinodal decomposition, and the Ostwald ripening is suppressed due to the low solute solubility of the matrix phase in the Cu–Ni–X (X = Co,Fe) system. Hence, the spinodal microstructure formed inside the grain before CD is trapped into high–energy level, which induces the discontinuous precipitation with high speed grain boundary migration, that provides “Cellular Decomposition”. [doi:10.2320/jinstmet.J2020037]
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