| 1. |
- Andersson, Nils-Eric, et al.
(författare)
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Fatigue crack growth rate in thick plates of 7010
- 1999
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Ingår i: Fatigue '99. - Beijing : Higher Education Press. - 9787040075823 ; , s. 445-450
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A mapping of fatigue crack growth rates in thick plates of a high strength aluminium alloy has been done. The plate thicknesses investigated was 100, 150 and 200 mm. In this work, material from near edge at near surface and mid-thickness has been investigated. Measurements of crack length has been performed using DC potential drop. Cyclic condensation is used in order to reveal crack growth behaviour for stage I and the earlier part of stage II crack growth. Influence of crack closure, crack branching and slow growing side cracks on fatigue crack growth rate of S-L and L-T oriented specimens are discussed. Variation of difference in growth rate in the upper part of the stage II growth between near surface and mid thickness positioned L-T specimens are found to vary with plate thickness.
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| 2. |
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| 3. |
- Andersson, Nils-Eric, et al.
(författare)
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Influence of recrystallisation on properties of AA7010 thick plate
- 1998
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Ingår i: ICAA-6. ; , s. 1191-1196
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The variations in structure and mechanical properties of AA7010 thick plate have been investigated. The studied plate thicknesses were 100-200 mm and the material was overaged and stress relieved. The material studied is frequently used to produce load-carrying airframe components. The focus of this paper is the influence of recrystallisation. The degree of recrystallisation was determined as a function of position in the mid width of the plates by using optical microscopy and image analysis. The crystallographic orientation of recrystallised grains were determined from EBSP maps. Hardness measurements on subgrain areas and on recrystallised grains were done by micro hardness indentations in order to reveal the effect of recrystallisation on yield strength. The fracture toughness at different positions of the plates are discussed in terms of influence from recrystallisation. The paper also discusses the mechanisms behind the recrystallisation and its influence on mechanical properties such as yield strength and fracture toughness. The suggested influence of recrystallisation on the mechanical properties are compared to the influence seen from other parameters such as chemical composition, quench rate, texture, grain size, distribution and sizes of inclusions, dispersoids and ageing precipitates.
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| 4. |
- Andersson, Nils-Eric, et al.
(författare)
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The influence of hot rolling on the variation of through thickness structure of AA7010 thick plates
- 1997
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Ingår i: Thermo-Mechanical Processing in Theory, Modelling & Practice. - Stockholm : Svenska fören. för materialteknik. - 9163054213 ; , s. 284-289
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The variation of through thickness structure and yield strength of AA7010-T7451 thick plate has been investigated. Grain size at different depths were determined qualitatively by using optical microscopy. Texture measurements were carried out using x-ray technique at the same depths as grain size studies. Tensile property tests have been performed and the EBSP technique has been used to compare the degree of recovered and recrystallized grain structure at different depths. Tensile testing determined through thickness variations in yield. The expected W shape of longitudinal yield strength through thickness was not observed. The yield strength decreases towards the center of the plate. An increasing amount of big recrystallized grains (through the thickness from T/8 towards the center of the plate) appears to be the reason behind the decreasing through thickness yield strength.
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| 5. |
- Andersson, Nils-Eric, et al.
(författare)
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The influence of hot rolling on the variation of through thickness structure of AA7010 thick plates
- 1996
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Ingår i: Thermomechanical processing in theory, modelling and practice [TMP]2. - 9163054213 ; , s. 284-289
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The variation of through thickness structure and yield strength of AA7010-T7451 thick plate has been investigated. Grain sizes at different depths were determined qualitatively by using optical microscopy. Texture measurements were carried out using X-ray technique at the same depths as grain size studies and tensile property tests have been performed. EBSP techdque has been used to compare the degree of recovered and recrystallized grain structure at different depths. Tensile testing determined through thickness variations in yield strength. The well known W shape of longitudinal yield strength variation through the thickness was not observed. The influence of texture on the yield strength measured is discussed.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Johansson, Sten R, et al.
(författare)
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Serum lipids and lipoproteins in relation to restenosis after coronary angioplasty.
- 1991
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Ingår i: European heart journal. - 0195-668X. ; 12:9, s. 1020-8
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Tidskriftsartikel (refereegranskat)abstract
- Restenosis after coronary angioplasty (PTCA) is a major problem, limiting the long-term efficacy of the procedure. Lipoprotein levels are associated with the development of atherosclerosis and may also be associated with restenosis. In this study the serum levels of cholesterol (CH), triglycerides (TG), high density lipoprotein (HDL) and low density lipoprotein (LDL) were analysed in 157 patients undergoing 161 PTCA procedures. Follow-up coronary angiograms were performed after 6.0 +/- 4.3 months. The restenosis rate was 33%. Treatment with aspirin and a residual stenosis of 25-49% immediately after successful PTCA were the only variables associated with restenosis (P less than 0.05), otherwise the clinical and angiographic characteristics were similar with and without restenosis. There was no relationship between restenosis and the levels of CH, TG, HDL or LDL (P greater than 0.05). In univariate and multivariate analysis of males (n = 121) and females (n = 40) separately, restenosis was associated with low HDL in men and high HDL in women (P less than 0.05), but not with CH, TG or LDL (P greater than 0.05). We conclude that the serum levels of CH, TG and LDL do not seem to be related to restenosis after PTCA. It is suggested that low HDL in males and high HDL in females is related to restenosis.
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| 10. |
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