Haynes® 282® is a relatively new precipitation strengthened nickel-based superalloy typically used in the hotsections of jet engines. The alloy is most commonly used in its wrought form, however Haynes® 282® castings have been of interest in the industry lately as they can offer increased flexibility, e.g. ability to cast advanced geometries to final shapes, and cost advantages. As expected however, castings present challenges related toboth mechanical properties and manufacturing. In particular, the large grains and dendritic structure theypresent make it difficult to laser weld specimens thicker than 8 mm due to cracking in the heat affected zone. GKN has identified a heat treatment that improves the weldability and reduces cracking, however this improved pre-weld heat treatment has a relatively long duration.The purpose of this thesis is therefore to optimize the pre-weld heat treatment with regards to liquation cracking while also reducing total heat treatment time. The proposed heat treatment selection was based on a literature survey, discussions with experts as well as previous results at GKN. Heat treated cast plates with thickness 8 mm were laser welded (bead-on-plate) and subsequently examined metallographically. Three proposed heat treatments showed a potential improvement while two heat treatments seem to have achieved similar results as the GKN heat treatment however at a significantly reduced total heat treatment time. These results were complimented with microstructural analysis and hardness measurements to improve our understanding of pre-weld microstructure on hot cracking.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:ltu-105700 |
| Date | January 2023 |
| Creators | Zaheraldin, Mehdi |
| Publisher | Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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