Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel
In the present work, the influence of the cooling time on the mechanical performance, hardness, and microstructural features of a double pulse resistance spot welded medium-Mn steel are investigated. Curves of the electrical resistance throughout the welding revealed that the cooling time strongly i...
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| Format: | Article |
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MDPI AG
2021-02-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/11/2/270 |
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| author | Manfred Stadler Ronald Schnitzer Martin Gruber Katharina Steineder Christina Hofer |
| author_facet | Manfred Stadler Ronald Schnitzer Martin Gruber Katharina Steineder Christina Hofer |
| author_sort | Manfred Stadler |
| collection | DOAJ |
| description | In the present work, the influence of the cooling time on the mechanical performance, hardness, and microstructural features of a double pulse resistance spot welded medium-Mn steel are investigated. Curves of the electrical resistance throughout the welding revealed that the cooling time strongly influences the heat generation during the second pulse. A second pulse after a short cooling time re-melts the center, and heat treats the edge of the primary fusion zone. This desired in-process heat treatment leads to a modification of the cast-like martensitic structure by recrystallization illustrated by electron backscatter diffraction measurements and to a homogenization of manganese segregations, visualized by energy-dispersive X-ray spectroscopy, which results in an enhanced mechanical performance during the cross tension strength test. In contrast, during excessively long cooling times, the resistance drops to a level where the heat generation due to the second pulse is too low to sufficiently re-heat the edge of the primary FZ. As a consequence, the signs of recrystallization disappear, and the manganese segregations are still present at the edge of the fusion zone, which leads to a deterioration of the mechanical properties. |
| first_indexed | 2024-03-09T05:35:45Z |
| format | Article |
| id | doaj.art-93bb676a9b5f4803843e0a7b98e78741 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-09T05:35:45Z |
| publishDate | 2021-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-93bb676a9b5f4803843e0a7b98e787412023-12-03T12:29:08ZengMDPI AGMetals2075-47012021-02-0111227010.3390/met11020270Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn SteelManfred Stadler0Ronald Schnitzer1Martin Gruber2Katharina Steineder3Christina Hofer4Department of Materials Science, Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben, AustriaDepartment of Materials Science, Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben, Austriavoestalpine Stahl GmbH, voestalpine-Strasse 3, 4020 Linz, Austriavoestalpine Stahl GmbH, voestalpine-Strasse 3, 4020 Linz, AustriaDepartment of Materials Science, Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben, AustriaIn the present work, the influence of the cooling time on the mechanical performance, hardness, and microstructural features of a double pulse resistance spot welded medium-Mn steel are investigated. Curves of the electrical resistance throughout the welding revealed that the cooling time strongly influences the heat generation during the second pulse. A second pulse after a short cooling time re-melts the center, and heat treats the edge of the primary fusion zone. This desired in-process heat treatment leads to a modification of the cast-like martensitic structure by recrystallization illustrated by electron backscatter diffraction measurements and to a homogenization of manganese segregations, visualized by energy-dispersive X-ray spectroscopy, which results in an enhanced mechanical performance during the cross tension strength test. In contrast, during excessively long cooling times, the resistance drops to a level where the heat generation due to the second pulse is too low to sufficiently re-heat the edge of the primary FZ. As a consequence, the signs of recrystallization disappear, and the manganese segregations are still present at the edge of the fusion zone, which leads to a deterioration of the mechanical properties.https://www.mdpi.com/2075-4701/11/2/270advanced high strength steelsAHSSmedium-Mn steelresistance spot weldingdouble pulsingdynamic resistance curves |
| spellingShingle | Manfred Stadler Ronald Schnitzer Martin Gruber Katharina Steineder Christina Hofer Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel Metals advanced high strength steels AHSS medium-Mn steel resistance spot welding double pulsing dynamic resistance curves |
| title | Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel |
| title_full | Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel |
| title_fullStr | Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel |
| title_full_unstemmed | Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel |
| title_short | Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel |
| title_sort | influence of the cooling time on the microstructural evolution and mechanical performance of a double pulse resistance spot welded medium mn steel |
| topic | advanced high strength steels AHSS medium-Mn steel resistance spot welding double pulsing dynamic resistance curves |
| url | https://www.mdpi.com/2075-4701/11/2/270 |
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