| 1. |
- Arén, Björn, et al.
(författare)
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Investigation of hot iostatic pressing of metal powder to near net shape
- 1988
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Ingår i: HIP. - Luleå : CENTEK. - 918699834X ; , s. 117-124
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Konferensbidrag (refereegranskat)abstract
- Shape control during HIP is influenced by many variables such as container properties, powder filling method, initial density, temperature and pressure cycle, etc. Experiments have been performed using ASP30 aimed at the study of how to produce parts near net shape through the optimization of these variables. Special care was given to the powder filling and laser welded sheet metal containers of special geometry was used. The results indicate that the temperature and pressure cycles during the first stages of the HIP-process have a pronounced effect on the final shape. A HIP-cycle which will result in a close shape is also presented. Graphs
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| 2. |
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| 3. |
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| 4. |
- Li, Wen-Bin, et al.
(författare)
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On densification and shape change during hot isostatic pressing
- 1987
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Ingår i: Acta Metallurgica. - Cambridge : Elsevier BV. - 0001-6160. ; 35:12, s. 2831-2842
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Tidskriftsartikel (refereegranskat)abstract
- When the temperature of a powder compact is raised, heat diffuses inwards from the surface. If the compact is under pressure (as it is during HIPing), the surface layers start to densify, increasing the local thermal conductivity. Under certain conditions a densification front then propagates into the powder, and this leads to changes of shape of the compact, which is no longer identical to the preform shape. The conditions which lead to non-uniform densification are analysed and the consequences are discussed, and compared with experiments
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| 5. |
- Li, Wen-Bin, et al.
(författare)
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On the Zener drag pressure by cubic shaped particles
- 1988
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Ingår i: Strength of metals and alloys. - Amsterdam : Elsevier. - 0080348041 ; , s. 1345-1350
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Konferensbidrag (refereegranskat)abstract
- All models of the Zener drag effect, in which precipitate particles hinder the movement of migrating grain boundaries, are based on spherical or ellipsoidal particles. Zener drag by cubic shaped particles is modelled. It is shown that cubic particles are generally more effective than spherical particles in holding up grain growth, and that coherent particles are better in this respect that incoherent particles
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| 6. |
- Li, Wen-Bin, et al.
(författare)
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Residual stresses in laser transformation hardened steel
- 1986
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Ingår i: Surface Engineering. - : Informa UK Limited. - 0267-0844 .- 1743-2944. ; 2:1, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- A simple analytical solution is developed for calculating the residual stresses which occur as a result of the laser transformation hardening of steel surfaces. The solution is based mainly on taking account of the dilatation resulting from the martensitic transformation and allows the influence of the many and varied parameters involved in laser transformation hardening (beam size and intensity, material properties, composition, etc.) to be readily assessed. Satisfactory agreement between the theoretical predictions and reported experimental measurements of residual stress is obtained
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| 7. |
- Li, Wen-Bin, et al.
(författare)
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Stresses developed in the hot iostatic pressing of metals and ceramics
- 1988
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Ingår i: HIP. - : CENTEK. - 918699834X ; , s. 97-105
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Konferensbidrag (refereegranskat)abstract
- The state of residual stresses brought about during and after HIPing is decided by a number of factors, including material properties and the HIP-cycle parameters. The residual stresses following HIPing can be tensile or compressive, depending on the balance of three contributions , i.e. creep, elastic and thermal stresses. The contribution of creep of total stress is always negative (compressive) and by the elastic part always positive (tensile), but the stresses caused by thermal dilatation yield positive or negative stresses depending on the input parameters. Therefore, the general pattern of residual stresses after HIPing is fairly complicated. Usually, however, the sum of the contributions leads to tensile--tangential and compressive radial stresses (in Al, Cu, ceramics).
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| 8. |
- Ringer, S.P., et al.
(författare)
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On the interaction and pinning of grain boundaries by cubic shaped precipitate particles
- 1989
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Ingår i: Acta Metallurgica. - : Elsevier BV. - 0001-6160. ; 37:3, s. 831-841
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Tidskriftsartikel (refereegranskat)abstract
- Previous models of the Zener pinning of migrating grain boundaries by precipitates are all based on spherical or ellipsoidal particles. In this work, theoretical and experimental studies are made of pinning by stable, cubic-shaped particles. It is shown that cubic-shaped particles are generally more effective than spherical particles in holding up grain growth. Pinning is also more effective if particles are fully coherent. Transmission electron microscopy is used to study actual grain boundary/particle interactions in a Ti-microalloyed steel in which the coherent precipitate is a stable, cubic-shaped titanium nitride compound. The interactions observed are discussed in the light of the models developed
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