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- Åsberg, Mikael, et al.
(författare)
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Influence of post treatment on microstructure, porosity and mechanical properties of additive manufactured H13 tool steel
- 2019
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 742, s. 584-589
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (AM) is an attractive manufacturing technology in tooling applications. It provides unique opportunities to manufacture tools with complex shapes, containing inner channels for conformal cooling. In this investigation, H13, a widely used tool steel, was manufactured using a laser powder bed fusion method. Microstructure, tensile mechanical properties, hardness, and porosity of the AM H13 after stress relieve (SR), standard hardening and tempering (SR + HT), and hot isostatic pressing (SR + HIP + HT) were investigated. It was found that the microstructure of directly solidified colonies of prior austenite, which is typical for AM, disappeared after austenitizing at the hardening heat treatment. In specimens SR + HT and SR + HIP + HT, a microstructure similar to the conventional but finer was observed. Electron microscopy showed that SR and SR + HT specimens contained lack of fusion, and spherical gas porosity, which resulted in remarkable scatter in the observed elongation to break values. Application of HIP resulted in the highest strength values, higher than those observed for conventional H13 heat treated in the same way. The conclusion is that HIP promotes reduction of porosity and lack of fusion defects and can be efficiently used to improve the mechanical properties of AM H13 tool steel.
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- Bergström, Jens, et al.
(författare)
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Fatigue of cold work tool steel
- 1999
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Ingår i: Matériaux & Techniques. - : EDP Sciences. - 0032-6895 .- 1778-3771. ; 87:1-2, s. 9-14
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Tidskriftsartikel (refereegranskat)abstract
- One important surface property of forming tools is their resistance to cracking due to fatigue loading. The wide variety of steel grades, material handling, machining operations and surface treatments will give very different fatigue properties. The present article gives examples on the influence of steel grades, EDM machining and surface coating. Initial cracks may be introduced in the tool during the processing to its final shape and surface finish, why a particular interest is given to small cracks introduced by the EDM process.
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