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| 2. |
- Andersson, Joel, 1981-, et al.
(författare)
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Effect of Different Solution Heat Treatments on the Hot Ductility of Superalloys : Part 3 - Waspaloy
- 2013
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Ingår i: Materials Science and Technology. - 0267-0836 .- 1743-2847. ; 29:1, s. 43-53
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Tidskriftsartikel (refereegranskat)abstract
- The susceptibility to heat affected zone cracking of Waspaloy has been investigated in terms of its hot ductility, measured as the reduction of area (RA). Gleeble testing with on-heating as well as on-cooling test cycles was carried out to illuminate the influence of different 4 h solution heat treatments between 996 and 1080°C. A ductility maximum of between 80 and 90%RA was found at 1050–1100°C for all conditions in the on-heating tests. Although the different heat treatment conditions showed similar macrohardness, the particle size and distribution of the γ′ and M23C6 phases differed, which significantly affected the on-heating ductility in the lower temperature test region. The ductile to brittle transition was initiated at 1100°C in the on-heating testing with indications of grain boundary liquation at the higher test temperatures. Ductility recovery, as measured in the on-cooling tests from 1240°C, was very limited with <30%RA for all conditions and test temperatures except for the 1080°C/4 h treatment, which exhibited 60%RA at 980°C.
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| 3. |
- Andersson, Joel, 1981-, et al.
(författare)
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Effect of solution heat treatments on superalloys : Part 1 – alloy 718
- 2012
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Ingår i: Materials Science and Technology. - : Taylor & Francis Group. - 0267-0836 .- 1743-2847. ; 28:5, s. 609-619
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Tidskriftsartikel (refereegranskat)abstract
- The hot ductility as measured by Gleeble testing of Alloy 718 at four different solution heat treatments (954°C/15 h, 954°C/1 h, 982°C/1 h and 1050°C/3 h+954°C/1 h) has been investigated. It is concluded that constitutional liquation of NbC assisted by δ phase takes place and deteriorates the ductility. Parameters established by analysing the ductility dependence on temperature indicate a reduced weldability of the material in the coarse grain size state (ASTM 3) while indicating an increased weldability when containing a large amount of δ phase due to a grain boundary pinning effect. The accumulation of trace elements during grain growth at the highest temperature is believed to be the cause for the observed reduced on-cooling ductility.
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| 4. |
- Andersson, Joel, 1981-, et al.
(författare)
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Hot Ductility Study of Haynes 282 Superalloy
- 2010
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Ingår i: Superalloy 718 and Derivatives. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9780470943168 ; 2, s. 539-554
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Konferensbidrag (refereegranskat)
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| 7. |
- Coll Ferrari, Maria Teresa, et al.
(författare)
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Influence of lowered austenitisation temperature during hardening on tempering resistance of modified H13 tool steel (Uddeholm Dievar)
- 2013
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Ingår i: International Heat Treatment and Surface Engineering. - : Taylor & Francis. - 1749-5156. ; 7:3, s. 129-132
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Tidskriftsartikel (refereegranskat)abstract
- The surface of large tools will be exposed to the hardening temperature for longer times than the core. This might in occasions, result in grain growth. In order to prevent this, it has become practice to lower the hardening temperature. This paper presents the effect of this practice on the precipitation of tempering carbides and the tempering resistance of Uddeholm Dievar. Composition of equilibrium austenite and the undissolved carbides at two different hardening temperatures were estimated by Thermo Calc simulations and the calculations predict that the balance between the amounts of molybdenum and vanadium in the austenite is shifted towards more molybdenum at the lower austenitising temperature. Since molybdenum stabilises M2C precipitates, it was predicted also that the tempering carbides would be almost only M2C in the sample with the lower austenitising temperature, whereas for the higher austenitising temperature, the subsequent tempering would yield a mixture of the much more stable MC together with M2C. Samples were hardened at the simulated temperatures and tempered. The existing carbides were investigated with help of SEM and TEM. The result shows that a lowered austenitisation temperature decreases the tempering resistance. However, the transmission electron microscopy reveals that both samples have the same mixture of tempering carbides, as the samples do not reach thermodynamical equilibrium during the holding time at the hardening temperature. The lower austenitising temperature gives less tempering carbides as less alloying elements are dissolved.
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| 8. |
- Dahlmo, K I, et al.
(författare)
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On a new method to assess the accuracy of a CAD program.
- 2001
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Ingår i: International Journal of Prosthodontics. - : Quintessence Publishing. - 0893-2174 .- 1139-9791. ; 14:3, s. 276-83
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: This study was initiated with the purpose of developing and evaluating a system for measuring the magnitude of the variation between a computer-aided design (CAD) object created on the computer screen and a replicated object produced by computer-aided manufacturing (CAM). MATERIALS AND METHODS: Controlled geometric forms, a square and a cone, were designed in a CAD program, and measuring distances were selected. The CAD data were transmitted to CAM data, and objects were produced. The CAD/CAM process was the Procera system, and the holder system permitted the objects to be ground into cross sections, similar to the visualization in the CAD program. Five objects of each shape were produced and measured by two operators two times. Three operators measured one of the objects 30 times. RESULTS: Observed values were greater than the true value. For all objects, the systematic error was at most 15.5 microns. Interoperator difference was small. The variation because of measurement error was greater for the square object compared to the cone. However, the variation because of object was higher for the cone object than for the square. The total standard deviation was 7.7 microns. Thus, the total random error caused by object variation and measurement error was in approximately 95% of all measurements less than 15 microns. CONCLUSION: There are no differences in the measurement data derived from this method and actual measurement data from an object created by the computer-aided dental design program. The method has high validity and reliability, i.e., high accuracy.
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| 9. |
- Eriksson, Erik, et al.
(författare)
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The Effect of Grain Boundary Carbides on Dynamic Recrystallization During Hot Compression of Ni-Based Superalloy Haynes 282 TM
- 2021
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer. - 1073-5623 .- 1543-1940.
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Tidskriftsartikel (refereegranskat)abstract
- In alloys where carbides are the main grain boundary phase, the role of carbides during hot working is not known. Here, we address the effect of grain boundary carbides on the dynamic recrystallization during hot compression of Ni-base superalloy Haynes 282. When excluding variations from experimental factors neither stress evolution nor final microstructure indicated that carbides exerted a significant influence on the dynamic recrystallization. The carbide solvus temperature is not a critical limit during thermomechanical processes.
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