{"title":"Nondestructive Testing for Infrastructure Maintenance Using Ultra-compact X-ray and Neutron Sensors","authors":"A. Koike, T. Aoki","doi":"10.2207/JJWS.90.76","DOIUrl":"https://doi.org/10.2207/JJWS.90.76","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"5 1","pages":"76-82"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68680017","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}
Active-TIG (A-TIG) or Advanced Active-TIG (AA-TIG) welding is an effective method to improve the welding penetration depth by introducing of active elements such as oxygen into the weld metal. However, increasing oxygen content in the weld metal decreases the toughness of the weld metal. Grain refinement is regarded as one of the most effective ways to improve the toughness of materials. Friction stir processing (FSP) is suitable for reducing grain size in small area such as the weld metal. This study elucidates the effect of FSP on the toughness of 9%Ni steel weld metal containing different oxygen contents. The 9%Ni steel weld metal were fabricated via AA-TIG welding using a mixed gas of Ar and O 2 . The oxygen contents in the weld metal were 180, 250, and 330ppm. FSP treated the weld metal formed via AA-TIG welding. The microstructures of the weld metal and stir zone were observed using the optical microscope (OM), scanning electron microscope (SEM), and electron backscatter diffraction (EBSD). The micro-impact test was conducted to measure the toughness of the weld metal and stir zone. Although the toughness of the weld metal decreased with increasing oxygen content in the weld zone, FSP could improve it regardless of the oxygen content in the stir zone. In particular, the toughness of the stir zone with oxygen content of 330ppm was considerably increased, and it reached almost the same value as the base metal. These improvements depend on the grain refinement in the stir zone. The smallest grain size of former austenite was obtained in the stir zone with an oxygen content of 330ppm because numerous small inclusion particles lead to clear pining effect.
{"title":"Effect of Friction Stir Processing on Mechanical Properties of AA-TIG welded 9%Ni Steel","authors":"M. Mori, Tatsuya Tokuda, Y. Morisada, H. Fujii","doi":"10.2207/qjjws.39.200","DOIUrl":"https://doi.org/10.2207/qjjws.39.200","url":null,"abstract":"Active-TIG (A-TIG) or Advanced Active-TIG (AA-TIG) welding is an effective method to improve the welding penetration depth by introducing of active elements such as oxygen into the weld metal. However, increasing oxygen content in the weld metal decreases the toughness of the weld metal. Grain refinement is regarded as one of the most effective ways to improve the toughness of materials. Friction stir processing (FSP) is suitable for reducing grain size in small area such as the weld metal. This study elucidates the effect of FSP on the toughness of 9%Ni steel weld metal containing different oxygen contents. The 9%Ni steel weld metal were fabricated via AA-TIG welding using a mixed gas of Ar and O 2 . The oxygen contents in the weld metal were 180, 250, and 330ppm. FSP treated the weld metal formed via AA-TIG welding. The microstructures of the weld metal and stir zone were observed using the optical microscope (OM), scanning electron microscope (SEM), and electron backscatter diffraction (EBSD). The micro-impact test was conducted to measure the toughness of the weld metal and stir zone. Although the toughness of the weld metal decreased with increasing oxygen content in the weld zone, FSP could improve it regardless of the oxygen content in the stir zone. In particular, the toughness of the stir zone with oxygen content of 330ppm was considerably increased, and it reached almost the same value as the base metal. These improvements depend on the grain refinement in the stir zone. The smallest grain size of former austenite was obtained in the stir zone with an oxygen content of 330ppm because numerous small inclusion particles lead to clear pining effect.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67995875","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}
Kenta Iida, Keigo Tanaka, M. Shigeta, Hisaya Komen, Manabu Tanaka
The droplet ejection from an electrode during an alternative current tungsten inert gas (AC TIG) welding process was observed using a visualization system composed by a high-speed camera with a band-pass filter to clarify dominant factors of the droplet ejection. Different welding currents, electrode diameters and electrode positive (EP) ratios were set. The numbers of droplets ejected from the electrode tip were measured for the different conditions. The timings of droplet ejections from the electrode were also determined in one AC cycle. The results indicated that droplets were likely to be ejected when the welding current was high, when the electrode diameter was small, when the EP ratio was large, and in the latter half of the EP term. Because the electrode temperature under these welding conditions was higher, the high electrode temperature was considered to be a dominant factor for the droplet ejection. However, immediately after the start of the electrode negative (EN) term, the number of droplets decreased even though the electrode temperature was the highest in one AC cycle. Therefore, it was suggested that other factors affected the electrode ejection. Moreover, raised portions were formed on the surface of the molten electrode right before droplet ejections. It was considered that the formation of the raised part might be suppressed by the collision of positive ions in the arc plasma with the electrode at EN term. Estimated pressure due to the ion collision acting on the ridge was larger than that due to the surface tension and the electromagnetic force, respectively. Therefore, it was suggested that the collision of positive ions at EN term suppressed the droplet ejection.
{"title":"Experimental investigation of dominant factors for droplet ejection from electrode during AC TIG welding","authors":"Kenta Iida, Keigo Tanaka, M. Shigeta, Hisaya Komen, Manabu Tanaka","doi":"10.2207/qjjws.39.260","DOIUrl":"https://doi.org/10.2207/qjjws.39.260","url":null,"abstract":"The droplet ejection from an electrode during an alternative current tungsten inert gas (AC TIG) welding process was observed using a visualization system composed by a high-speed camera with a band-pass filter to clarify dominant factors of the droplet ejection. Different welding currents, electrode diameters and electrode positive (EP) ratios were set. The numbers of droplets ejected from the electrode tip were measured for the different conditions. The timings of droplet ejections from the electrode were also determined in one AC cycle. The results indicated that droplets were likely to be ejected when the welding current was high, when the electrode diameter was small, when the EP ratio was large, and in the latter half of the EP term. Because the electrode temperature under these welding conditions was higher, the high electrode temperature was considered to be a dominant factor for the droplet ejection. However, immediately after the start of the electrode negative (EN) term, the number of droplets decreased even though the electrode temperature was the highest in one AC cycle. Therefore, it was suggested that other factors affected the electrode ejection. Moreover, raised portions were formed on the surface of the molten electrode right before droplet ejections. It was considered that the formation of the raised part might be suppressed by the collision of positive ions in the arc plasma with the electrode at EN term. Estimated pressure due to the ion collision acting on the ridge was larger than that due to the surface tension and the electromagnetic force, respectively. Therefore, it was suggested that the collision of positive ions at EN term suppressed the droplet ejection.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67995977","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}
Shotaro Yamashita, K. Ueda, Atsushi Takada, D. Izumi, N. Sahara, T. Ogura, K. Saida
This paper reports on the effect of carbon, silicon, manganese, chromium and aluminum on solidification cracking susceptibility of high manganese steel. The solidification cracking susceptibility of high manganese steel has been evaluated by using trans-Varestraint test and BTR that is one of the evaluation index of the solidification cracking susceptibility was obtained and compared. According to quenched microstructure observation by EPMA and EBSD analysis, solidification mode at all material might be an austenite phase (single-phase), in addition MnS was observed in the weld metal of all tested samples with different chemical composition and M 3 P particle was observed only for 13%Cr material. A numerical analysis approach for solidification cracking susceptibility of high manganese steel depending on some solute elements was carried out to quantitatively evaluate the temperature range and confirm the validation of BTR and influence of the solidification phenomenon. Based on both temperature ranges obtained experimentally and analytically, the solidification cracking susceptibility increased with increasing carbon, silicon and manganese, and these doesn ’ t change by chromium content in the high manganese steel. And then, aluminum decreased the solidification cracking susceptibility, but it might be caused ductility-dip cracking in the steel.
{"title":"Effect of Alloying Elements on Solidification Cracking Susceptibility of High Manganese Austenitic Steel","authors":"Shotaro Yamashita, K. Ueda, Atsushi Takada, D. Izumi, N. Sahara, T. Ogura, K. Saida","doi":"10.2207/qjjws.39.87","DOIUrl":"https://doi.org/10.2207/qjjws.39.87","url":null,"abstract":"This paper reports on the effect of carbon, silicon, manganese, chromium and aluminum on solidification cracking susceptibility of high manganese steel. The solidification cracking susceptibility of high manganese steel has been evaluated by using trans-Varestraint test and BTR that is one of the evaluation index of the solidification cracking susceptibility was obtained and compared. According to quenched microstructure observation by EPMA and EBSD analysis, solidification mode at all material might be an austenite phase (single-phase), in addition MnS was observed in the weld metal of all tested samples with different chemical composition and M 3 P particle was observed only for 13%Cr material. A numerical analysis approach for solidification cracking susceptibility of high manganese steel depending on some solute elements was carried out to quantitatively evaluate the temperature range and confirm the validation of BTR and influence of the solidification phenomenon. Based on both temperature ranges obtained experimentally and analytically, the solidification cracking susceptibility increased with increasing carbon, silicon and manganese, and these doesn ’ t change by chromium content in the high manganese steel. And then, aluminum decreased the solidification cracking susceptibility, but it might be caused ductility-dip cracking in the steel.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67996232","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}
Hisaya Komen, Manabu Tanaka, A. Murata, Murata Tadasuke
** , TANAKA Manabu *** , MURATA Akihisa **** and MURATA Tadasuke **** Two-dimensional axisymmetric simulation was carried out to investigate heat source characteristics during an arc spot welding with a constricted nozzle. As a result, it was clarified that a part of the welding current flowed from a cooling nozzle which was an anode to a tungsten cathode directly. The temperature increase of the cathode tip was suppressed by the decrease of the Joule heating at the tip because of this separation of the current path. Comparing temperature and heat input density distributions on a base metal surface with a conventional tungsten inert gas (TIG) welding, there was no difference in the temperature on the central axis of the tungsten cathode, but the peak of the heat input density during the arc spot welding was lower than that in the TIG welding. In addition, the heat input range was narrower than that in the TIG welding by a cooling nozzle contacting the base metal. It was also clarified that the heat input to the base metal surface and the temperature increase of the tungsten electrode were suppressed by the nozzle. Inner gas flowing from the constricted nozzle cooled the outer edge of the arc plasma, suggesting that it contributed to the long lifetime of the tungsten electrode.
{"title":"Numerical Simulation of Heat Source Characteristics in Arc Spot Welding with Constricted Nozzle","authors":"Hisaya Komen, Manabu Tanaka, A. Murata, Murata Tadasuke","doi":"10.2207/qjjws.39.132","DOIUrl":"https://doi.org/10.2207/qjjws.39.132","url":null,"abstract":"** , TANAKA Manabu *** , MURATA Akihisa **** and MURATA Tadasuke **** Two-dimensional axisymmetric simulation was carried out to investigate heat source characteristics during an arc spot welding with a constricted nozzle. As a result, it was clarified that a part of the welding current flowed from a cooling nozzle which was an anode to a tungsten cathode directly. The temperature increase of the cathode tip was suppressed by the decrease of the Joule heating at the tip because of this separation of the current path. Comparing temperature and heat input density distributions on a base metal surface with a conventional tungsten inert gas (TIG) welding, there was no difference in the temperature on the central axis of the tungsten cathode, but the peak of the heat input density during the arc spot welding was lower than that in the TIG welding. In addition, the heat input range was narrower than that in the TIG welding by a cooling nozzle contacting the base metal. It was also clarified that the heat input to the base metal surface and the temperature increase of the tungsten electrode were suppressed by the nozzle. Inner gas flowing from the constricted nozzle cooled the outer edge of the arc plasma, suggesting that it contributed to the long lifetime of the tungsten electrode.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67996166","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}
{"title":"Multi-physics Analysis for Spot Welding","authors":"S. Hirano, S. Fukumoto, Shinji Koyama","doi":"10.2207/JJWS.90.176","DOIUrl":"https://doi.org/10.2207/JJWS.90.176","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"90 1","pages":"176-176"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68676091","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}
{"title":"Participation Report of the ASME Pressure Vessels & Piping 2020 Conference (PVP 2020)","authors":"Fuminori Iwamatsu","doi":"10.2207/JJWS.90.215","DOIUrl":"https://doi.org/10.2207/JJWS.90.215","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"47 1","pages":"215-217"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68676941","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}
{"title":"What I Think Back in My 40th Year of Research Work","authors":"T. Kasuya","doi":"10.2207/JJWS.90.230","DOIUrl":"https://doi.org/10.2207/JJWS.90.230","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"14 1","pages":"230-233"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68677390","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}
{"title":"Approaches and Future Developments about Evaluation of Hydrogen Diffusion Behavior in Resistance Spot Welds","authors":"Nao Kawabe","doi":"10.2207/JJWS.90.257","DOIUrl":"https://doi.org/10.2207/JJWS.90.257","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"90 1","pages":"257-258"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68677663","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}
{"title":"R&D of Digital Twin for Ship Structures","authors":"M. Fujikubo","doi":"10.2207/JJWS.90.36","DOIUrl":"https://doi.org/10.2207/JJWS.90.36","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":"90 1","pages":"36-43"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68678494","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}
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