Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Mechanical Engineering | en_US |
| dc.contributor.advisor | Jiao, Zengbao (ME) | en_US |
| dc.creator | Zhang, Xizheng | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/13017 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Microstructure and mechanical properties of precipitation-strengthened superalloys by additive manufacturing | en_US |
| dcterms.abstract | Ni-based superalloys are metallic materials with strong high-temperature stability, and have excellent high-temperature strength, oxidation resistance, and good plasticity and toughness. However, many problems such as harmful phases, defects, segregation, and residual stress exist in Ni-based superalloy parts processed by traditional methods such as casting, forging, and powder metallurgy, which seriously affect the performance of the alloy. There are also bottlenecks in other aspects. Selective laser melting (SLM) technology, as the most potential additive manufacturing method, provides the possibility to process Ni-based superalloy parts with low cost, short production cycle and complex shapes. The microstructure and mechanical properties are of great significance. | en_US |
| dcterms.abstract | In this dissertation, the influence of heat treatment on the precipitates and mechanical properties of SLM-formed Inconel 625 and Inconel 718 alloys was systematically studied, the mechanism controlling the precipitation behavior of additive Inconel 625 and Inconel 718 alloys was revealed, and the relationship between precipitates and mechanical properties of additive Ni-based superalloys was clarified. The main research contents and conclusions are as follows: | en_US |
| dcterms.abstract | Heat treatment of SLM formed Inconel 625 alloy at different temperatures and times, for example, after solution treatment at 1150 °C and then aging at 700 °C, or directly at 600 °C to 900 °C for aging treatment. The results show that the mechanical properties of IN625 alloy after direct aging treatment are better than those of the initial state and after solution treatment. After aging at 700 °C for 240h, a few needle-like δ phases are precipitated, and the fracture strength reaches the highest (~1118 MPa). In addition, heat treatment of SLM formed Inconel 718 alloy at different temperatures and times, mainly including solution treatment at 1050 °C and double aging treatment at 720 °C plus 620 °C, and aging treatment at 720 °C or 620 °C directly. The results show that the mechanical properties of the alloy after heat treatment are better than those of the initial state, and the elongation of the alloy after solution is generally higher than that after direct aging under the condition that the tensile strength is not much different. | en_US |
| dcterms.extent | ix, 62 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2023 | en_US |
| dcterms.educationalLevel | M.Sc. | en_US |
| dcterms.educationalLevel | All Master | en_US |
| dcterms.LCSH | Heat resistant alloys | en_US |
| dcterms.LCSH | Additive manufacturing | en_US |
| dcterms.LCSH | Laser beams | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | restricted access | en_US |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 7485.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 4.61 MB | Adobe PDF | View/Open |
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