Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding
Bobbin friction stir welding (BFSW) is an innovative variant for the solid state welding process whereby a rotating symmetrical tool causes a fully penetrated bond. Despite the process development, there are still unknown variables in the characterization of the process parameters which can cause un...
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ftmdpi:oai:mdpi.com:/2075-4701/8/1/33/ 2023-08-20T04:10:07+02:00 Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding Abbas Tamadon Dirk Pons Kamil Sued Don Clucas 2018-01-05 application/pdf https://doi.org/10.3390/met8010033 EN eng Multidisciplinary Digital Publishing Institute https://dx.doi.org/10.3390/met8010033 https://creativecommons.org/licenses/by/4.0/ Metals; Volume 8; Issue 1; Pages: 33 bobbin friction stir welding sprayed entry defect keyhole exit defect material flow analogue modelling plasticine AA6082-T6 Text 2018 ftmdpi https://doi.org/10.3390/met8010033 2023-07-31T21:20:16Z Bobbin friction stir welding (BFSW) is an innovative variant for the solid state welding process whereby a rotating symmetrical tool causes a fully penetrated bond. Despite the process development, there are still unknown variables in the characterization of the process parameters which can cause uncontrolled weld defects. The entry zone and the exit zone consist of two discontinuity-defects and removing them is one of the current challenges for improving the weld quality. In the present research, the characteristic features of the entry and exit defects in the weld structure and formation mechanism of them during the BFSW processing was investigated. Using stacked layers of multi-colour plasticine the material flow, analogous to metal flow, can be visualised. By using different colours as the path markers of the analogue model, the streamline flow can be easily delineated in the discontinuity defects compared with the metal welds. AA6082-T6 aluminium plates and multi-layered plasticine slabs were employed to replicate the entry-exit defects in the metal weld and analogue samples. The fixed-bobbin tool utilized for this research was optimized by adding a thread feature and tri-flat geometry to the pin and closed-end spiral scrolls on both shoulder surfaces. Samples were processed at different rotating and longitudinal speeds to show the degree of dependency on the welding parameters for the defects. The analogue models showed that the entry zone and the exit zone of the BFSW are affected by the inhomogeneity of the material flow regime which causes the ejection or disruption of the plastic flow in the gap between the bobbin shoulders. The trial aluminium welds showed that the elimination of entry-exit defects in the weld body is not completely possible but the size of the defects can be minimized by modification of the welding parameters. For the entry zone, the flow pattern evolution suggested formation mechanisms for a sprayed tail, island zone and discontinuity-channel. For the exit zone a keyhole-shaped ... Text Tail Island MDPI Open Access Publishing Keyhole ENVELOPE(-67.338,-67.338,-68.785,-68.785) Tail Island ENVELOPE(-57.624,-57.624,-63.670,-63.670) Metals 8 1 33 |
institution |
Open Polar |
collection |
MDPI Open Access Publishing |
op_collection_id |
ftmdpi |
language |
English |
topic |
bobbin friction stir welding sprayed entry defect keyhole exit defect material flow analogue modelling plasticine AA6082-T6 |
spellingShingle |
bobbin friction stir welding sprayed entry defect keyhole exit defect material flow analogue modelling plasticine AA6082-T6 Abbas Tamadon Dirk Pons Kamil Sued Don Clucas Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding |
topic_facet |
bobbin friction stir welding sprayed entry defect keyhole exit defect material flow analogue modelling plasticine AA6082-T6 |
description |
Bobbin friction stir welding (BFSW) is an innovative variant for the solid state welding process whereby a rotating symmetrical tool causes a fully penetrated bond. Despite the process development, there are still unknown variables in the characterization of the process parameters which can cause uncontrolled weld defects. The entry zone and the exit zone consist of two discontinuity-defects and removing them is one of the current challenges for improving the weld quality. In the present research, the characteristic features of the entry and exit defects in the weld structure and formation mechanism of them during the BFSW processing was investigated. Using stacked layers of multi-colour plasticine the material flow, analogous to metal flow, can be visualised. By using different colours as the path markers of the analogue model, the streamline flow can be easily delineated in the discontinuity defects compared with the metal welds. AA6082-T6 aluminium plates and multi-layered plasticine slabs were employed to replicate the entry-exit defects in the metal weld and analogue samples. The fixed-bobbin tool utilized for this research was optimized by adding a thread feature and tri-flat geometry to the pin and closed-end spiral scrolls on both shoulder surfaces. Samples were processed at different rotating and longitudinal speeds to show the degree of dependency on the welding parameters for the defects. The analogue models showed that the entry zone and the exit zone of the BFSW are affected by the inhomogeneity of the material flow regime which causes the ejection or disruption of the plastic flow in the gap between the bobbin shoulders. The trial aluminium welds showed that the elimination of entry-exit defects in the weld body is not completely possible but the size of the defects can be minimized by modification of the welding parameters. For the entry zone, the flow pattern evolution suggested formation mechanisms for a sprayed tail, island zone and discontinuity-channel. For the exit zone a keyhole-shaped ... |
format |
Text |
author |
Abbas Tamadon Dirk Pons Kamil Sued Don Clucas |
author_facet |
Abbas Tamadon Dirk Pons Kamil Sued Don Clucas |
author_sort |
Abbas Tamadon |
title |
Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding |
title_short |
Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding |
title_full |
Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding |
title_fullStr |
Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding |
title_full_unstemmed |
Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding |
title_sort |
formation mechanisms for entry and exit defects in bobbin friction stir welding |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2018 |
url |
https://doi.org/10.3390/met8010033 |
long_lat |
ENVELOPE(-67.338,-67.338,-68.785,-68.785) ENVELOPE(-57.624,-57.624,-63.670,-63.670) |
geographic |
Keyhole Tail Island |
geographic_facet |
Keyhole Tail Island |
genre |
Tail Island |
genre_facet |
Tail Island |
op_source |
Metals; Volume 8; Issue 1; Pages: 33 |
op_relation |
https://dx.doi.org/10.3390/met8010033 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/met8010033 |
container_title |
Metals |
container_volume |
8 |
container_issue |
1 |
container_start_page |
33 |
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1774724066470526976 |