On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part
Wire arc additive manufacturing (WAAM) is known to induce a considerable microstructural inhomogeneity and anisotropy in mechanical properties, which can potentially be minimized by adopting appropriate post-printing heat treatment. In this paper, the effects of two heat treatment cycles, including...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-06-01
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| Series: | Materials |
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| Online Access: | https://www.mdpi.com/1996-1944/13/12/2795 |
| _version_ | 1797564631384850432 |
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| author | Alireza Vahedi Nemani Mahya Ghaffari Ali Nasiri |
| author_facet | Alireza Vahedi Nemani Mahya Ghaffari Ali Nasiri |
| author_sort | Alireza Vahedi Nemani |
| collection | DOAJ |
| description | Wire arc additive manufacturing (WAAM) is known to induce a considerable microstructural inhomogeneity and anisotropy in mechanical properties, which can potentially be minimized by adopting appropriate post-printing heat treatment. In this paper, the effects of two heat treatment cycles, including hardening and normalizing on the microstructure and mechanical properties of a WAAM-fabricated low-carbon low-alloy steel (ER70S-6) are studied. The microstructure in the melt pools of the as-printed sample was found to contain a low volume fraction of lamellar pearlite formed along the grain boundaries of polygonal ferrite as the predominant micro-constituents. The grain coarsening in the heat affected zone (HAZ) was also detected at the periphery of each melt pool boundary, leading to a noticeable microstructural inhomogeneity in the as-fabricated sample. In order to modify the nonuniformity of the microstructure, a normalizing treatment was employed to promote a homogenous microstructure with uniform grain size throughout the melt pools and HAZs. Differently, the hardening treatment contributed to the formation of two non-equilibrium micro-constituents, i.e., acicular ferrite and bainite, primarily adjacent to the lamellar pearlite phase. The results of microhardness testing revealed that the normalizing treatment slightly decreases the microhardness of the sample; however, the formation of non-equilibrium phases during hardening process significantly increased the microhardness of the component. Tensile testing of the as-printed part in the building and deposition directions revealed an anisotropic ductility. Although normalizing treatment did not contribute to the tensile strength improvement of the component, it suppressed the observed anisotropy in ductility. On the contrary, the hardening treatment raised the tensile strength, but further intensified the anisotropic behavior of the component. |
| first_indexed | 2024-03-10T18:59:48Z |
| format | Article |
| id | doaj.art-f5649a28d7df409a8c7865521ca76ec5 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T18:59:48Z |
| publishDate | 2020-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-f5649a28d7df409a8c7865521ca76ec52023-11-20T04:30:38ZengMDPI AGMaterials1996-19442020-06-011312279510.3390/ma13122795On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S PartAlireza Vahedi Nemani0Mahya Ghaffari1Ali Nasiri2Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, CanadaFaculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, CanadaFaculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, CanadaWire arc additive manufacturing (WAAM) is known to induce a considerable microstructural inhomogeneity and anisotropy in mechanical properties, which can potentially be minimized by adopting appropriate post-printing heat treatment. In this paper, the effects of two heat treatment cycles, including hardening and normalizing on the microstructure and mechanical properties of a WAAM-fabricated low-carbon low-alloy steel (ER70S-6) are studied. The microstructure in the melt pools of the as-printed sample was found to contain a low volume fraction of lamellar pearlite formed along the grain boundaries of polygonal ferrite as the predominant micro-constituents. The grain coarsening in the heat affected zone (HAZ) was also detected at the periphery of each melt pool boundary, leading to a noticeable microstructural inhomogeneity in the as-fabricated sample. In order to modify the nonuniformity of the microstructure, a normalizing treatment was employed to promote a homogenous microstructure with uniform grain size throughout the melt pools and HAZs. Differently, the hardening treatment contributed to the formation of two non-equilibrium micro-constituents, i.e., acicular ferrite and bainite, primarily adjacent to the lamellar pearlite phase. The results of microhardness testing revealed that the normalizing treatment slightly decreases the microhardness of the sample; however, the formation of non-equilibrium phases during hardening process significantly increased the microhardness of the component. Tensile testing of the as-printed part in the building and deposition directions revealed an anisotropic ductility. Although normalizing treatment did not contribute to the tensile strength improvement of the component, it suppressed the observed anisotropy in ductility. On the contrary, the hardening treatment raised the tensile strength, but further intensified the anisotropic behavior of the component.https://www.mdpi.com/1996-1944/13/12/2795wire arc additive manufacturingER70S-6anisotropic mechanical propertiesmicrostructureheat treatment |
| spellingShingle | Alireza Vahedi Nemani Mahya Ghaffari Ali Nasiri On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part Materials wire arc additive manufacturing ER70S-6 anisotropic mechanical properties microstructure heat treatment |
| title | On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part |
| title_full | On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part |
| title_fullStr | On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part |
| title_full_unstemmed | On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part |
| title_short | On the Post-Printing Heat Treatment of a Wire Arc Additively Manufactured ER70S Part |
| title_sort | on the post printing heat treatment of a wire arc additively manufactured er70s part |
| topic | wire arc additive manufacturing ER70S-6 anisotropic mechanical properties microstructure heat treatment |
| url | https://www.mdpi.com/1996-1944/13/12/2795 |
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