| Title: |
Impact toughness of an electron-beam welded 0.2C direct-quenched and partitioned steel |
| Authors: |
Pallaspuro, S. (Sakari); Hesse, A.-C. (Ann-Christin); Engelke, T. (Tim); Sainio, J. (Johannes); Ghosh, S. (Sumit); Javaheri, V. (Vahid); Dilger, K. (Klaus); Kömi, J. (Jukka) |
| Publisher Information: |
Elsevier |
| Publication Year: |
2022 |
| Collection: |
Jultika - University of Oulu repository / Oulun yliopiston julkaisuarkisto |
| Subject Terms: |
advanced high-strength steel; direct quenching; electron-beam welding; impact toughness; partitioning; post weld heat treatment |
| Description: |
Third generation advanced high-strength steels, e.g., quenched and partitioned steels, are forthcoming structural materials, which consist of a martensitic matrix and a substantial proportion of stabilized residual austenite for improved deformability. A novel less energy-intensive processing route of direct-quenching and partitioning advances this concept by facilitating carbon partitioning to untransformed austenite directly from the quench-stop temperature. However, a major challenge also with these steels is how to maintain structural integrity in the welded end-products after additional heat-input reaching above a temperature where given microstructure is still stable. Heat-input limiting beam welding processes are a solution to this by minimizing degradation of the heat-affected zone (HAZ) and producing even-strength welded joints for S1100 and above. In this study, we report toughness properties of an electron-beam (EB) welded 0.2C-1.5Mn-0.5Si-0.8Al-1.1Cr-0.8Ni (wt.%) direct-quenched and partitioned steel (DQ&P) having a yield strength of ∼1100 MPa, and a direct-quenched (DQ) was used as a reference. Low-temperature post-weld heat treatment (PWHT) was considered, too. Weld seam, coarse-grained HAZ, and the base materials were tested for impact toughness. Both the DQ and DQ&P base materials have excellent impact toughness transition temperatures T28J below -100°C. The weld seam has very good low-temperature toughness already at this stage of optimisation with T28J of -66°C, which shows robustness of the chosen alloy. Increased residual austenite content increased upper shelf toughness but not T28J. Furthermore, both the DQ and DQP HAZs have T28J below -70°C, pointing to the weld seam as the weakest link. PWHT reduced low-temperature impact toughness in all the cases with T28J being above -40°C, clearly demanding reassessment of its feasibility. |
| Document Type: |
conference object |
| File Description: |
application/pdf |
| Language: |
English |
| Availability: |
http://urn.fi/urn:nbn:fi-fe202301102169 |
| Rights: |
info:eu-repo/semantics/openAccess ; © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) ; https://creativecommons.org/licenses/by-nc-nd/4.0/ |
| Accession Number: |
edsbas.D0E9F898 |
| Database: |
BASE |