| 1. |
- Flinkfeldt, Jan, et al.
(författare)
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Laser cladding in pre-made grooves : guide-lines for groove design
- 1994
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Ingår i: ASM Heat Treatment and Surface Engineering Conference II. - : Trans Tech Publications Inc.. ; , s. 423-428
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Konferensbidrag (refereegranskat)abstract
- Post machining of treated components after laser cladding are necessary in most cases. Depending on the quality of the chosen material this job could be laborious and time consuming. By preparing grooves of a certain design on the work piece before laser cladding, the excess material to be removed can be minimized and post machining operations facilitated. The paper describes experimental works with laser cladding in pre-made grooves on cast iron specimens to investigate the influence of special groove design on the cladding results. The results are discussed in terms of macro surface roughness, efficient layer thickness, residual stress in the cladded layer and base material intermixing in the cladding. The results indicate that laser cladding in grooves is a way to reduce cladding material consumption and to increase the coating rate.
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| 2. |
- Ion, John, et al.
(författare)
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Laser surface modification of a 13.5% Cr, 0.6% C steel
- 1991
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 26:1, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- A 13.5% Cr, 0.6% C steel, with an initial microstructure of chromium carbides in a ferrite matrix, was heat-treated by scanning a high-power laser beam over the surface. The aim was to compare the physical and chemical properties produced by this type of selective surface treatment with those resulting from a conventional furnace desensitization and quench-hardening heat treatment. Surface heating homogenized the carbon originally bound in the carbides sufficiently to produce martensite, giving hardening to levels comparable with a conventional heat treatment. Chromium-rich zones, carbides and retained austenite were also detected in the heated microstructure. Surface melting produced complete homogenization of both carbon and chromium, which resulted in the retention of large amounts of austenite in the microstructure on cooling to room temperature. Subsequent refrigeration at - 196 °C transformed some of the austenite to martensite. Pitting corrosion and local reductions in hardness were observed adjacent to treated areas under certain conditions, due to precipitation of secondary carbides and elevated tempering, respectively.
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| 3. |
- Magnusson, Claes, et al.
(författare)
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Creating tailor-made surfaces with high power CO2-lasers
- 1991
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Ingår i: Proceedings of the first ASM Heat Treatment and Surface Engineering Conference in Europe. - : Trans Tech Publications Inc.. - 0878496424 ; , s. 443-458
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Konferensbidrag (refereegranskat)
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| 4. |
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| 5. |
- Marklund, Göran, et al.
(författare)
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The double probe electric field experiment on Freja : Experiment description and first results
- 1994
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Ingår i: Space Science Reviews. - 0038-6308. ; 70:3-4, s. 483-508
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Tidskriftsartikel (refereegranskat)abstract
- A description is given of the Freja double-probe electric field instrument. Its capability to perform high-resolution measurements of the aurora and its fine-structure as well as collect information on sub-auroral and low-latitude phenomena is illustrated by selected results from the first six months of operation. The instrument is highly flexible and possible to operate in a number of different modes. It is also equipped with a 4-Megabyte burst memory for high data sampling rate and temporary storage of data. It has been fully operational since October 1992, and delivers data from ≈22 hr day-1 including about 5-6 auroral crossings of the northern and southern auroral ionosphere. New and important information on the auroral fine structure and electrodynamics is obtained by means of burst resolution data (6144 samples s-1) and normal resolution data (768 samples s-1). Common burst data collection triggered by the electric field event detector has turned out to be very useful for the selection of scientifically interesting events. This is illustrated by high-resolution data of a pair of extremely intense and narrow electric field structures (1 V m-1) which are associated with a total absence of precipitating particles, depletions of the thermal plasma and with an intense wave activity. The low inclination of the Freja orbit provides a new perspective for studying largescale phenomena associated with east-west gradients as is exemplified by electric field data from a satellite crossing over north-south oriented auroral structures presumably resulting from rotational distortions of east-west aligned auroral arcs. The different plasma regimes encountered by Freja are continuously monitored by means of current sweeps applied to the probes and by the satellite potential. In addition, overview data (8 samples s-1) are collected from full orbits and stored in the on-board memory and have proved to be extremely valuable, providing new information on global electric field phenomena at subauroral and lower latitudes, such as the intense poleward electric fields and Pc-1 observations that have been made near the plasmapause during substorm activity. © 1994 Kluwer Academic Publishers.
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