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Isothermal annealing of cold-rolled Al-Mn-Fe-Si alloy with different microchemistry states

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Transactions of Nonferrous Metals Society of China 2014年第12期24卷 3840-3847页

作者：黄科李彦军 knut MARTHINSEN Department of Materials Science and Engineering Norwegian University of Science and Technology (NTNU) SINTEF Materials and Chemistry

Microstructural evolution of a cold-rolled Al-Mn-Fe-Si alloy during annealing was studied. Except the as-cast variant, two other different homogenizations were considered, one gave a high density of fine dispersiods providing a considerable Zener drag influencing the softening behavior while the other gave a lower density of coarser dispersoid structure providing a much smaller drag effect. The gradual microstructural evolutions during annealing for the three variants were captured by interrupting annealing at different time. Effects of microchemistry state on recrystallization kinetics, recrystallized grain structure and texture were characterized by EBSD. It is demonstrated that the actual softening kinetics, final microstructure and texture are a result of delicate balance between processing condition and microchemistry state. Strong concurrent precipitation takes place in the case with high concentration of Mn in solid solution, which suppresses nucleation and retards recrystallization and finally leads to grain structure of coarse elongated grains dominated by a P texture component together with a ND-rotated cube component. On the contrary, when solute content of Mn is low and pre-existing dispersoids are relatively coarser, faster recrystallization kinetics is exhibited together with an equiaxed grain structure with mainly cube texture.

关键词： aluminum alloy Al-Mn-Fe-Si alloy recrystallization kinetics microchemistry precipitation recrystallization texture

High-accuracy turning with slender boring bars

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Advances in Manufacturing 2015年第2期3卷 105-110页

作者： knut SФrby Einar Sundseth Department of Production and Quality Engineering Norwegian University of Science and Technology Sandvik Teeness AS

The paper presents the theoretical background for new approaches for achieving high accuracy in finish turning with slender tools. The approaches are developed especially for high-accuracy turning with vibrations- damped boring bars with a length-to-diameter ratio up to 14. The approaches are based on established force models of turning operations and utilize a three-pass scheme where the deflection of the boring bar is calculated and compen- sated for in the final passes. Very good results are achieved in practical machining tests for a great variation of cutting conditions. Experiments show that the typical diameter error is 0.01 mm, even in situation where the tool deflection is 0.3 mm.

关键词： Turning Precision Boring bar

Effect of quenching rate on microstructure and mechanical properties of commercial AA7108 aluminium alloy

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Transactions of Nonferrous Metals Society of China 2012年第8期22卷 1872-1877页

作者： Ida WESTERMANN Ann Leni HAUGSTAD Yngve LANGSRUD knut MARTHINSEN SINTEF Materials and Chemistry NO-7465TrondheimNorway Department of Materials Science and Engineering Norwegian University of Science and TechnologyNO-7491TrondheimNorway Benteler Aluminium Systems Norway AS NO-2830RaufossNorway

A commercial AA7108 aluminium alloy subjected to different quenching procedures from the solid solution temperature of 480 ℃ was considered. Both continuously cooling and quenching to intermediate temperatures （400, 300 and 200 ℃） followed by different holding times were applied. All the materials were subsequently subjected to the same industrial two-step artificial ageing procedure to obtain a maximum strength （T6）. Tensile testing of the different quenched materials in the T6 temper reveals a large deviation in strength dependent on the cooling/holding time, compared with the reference sample. A collection of the different quenched materials was chosen for further investigation of the precipitate structure by transmission electron microscopy （TEM） to explain the differences in mechanical properties.

关键词： aluminium microstructure precipitate free zone mechanical properties

Correlating oriented grain number density of recrystallisation in particle-containing aluminium alloys

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Transactions of Nonferrous Metals Society of China 2018年第2期28卷 220-225页

作者：赵庆龙张辉迪 Ke HUANG knut MARTHINSEN 吉林大学材料科学与工程学院汽车材料教育部重点实验室长春130025 Laboratory of Thermomechanical Metallurgy-PX Group Chair Ecole Polytechnique Fédérale de Lausanne Department of Materials Science and Engineering Norwegian University of Science and Technology

The recrystallized grain structure of Al-（Mn）-Fe-Si alloys after isothermal annealing was studied by electron backscatter diffraction（EBSD） technique. Statistical correlation suggests that the frequency of forming P-oriented（{011}？566？） grains at a particle larger than the critical diameter（about 1.1 μm） is about 2% when the effect of fine dispersoids and concurrent precipitation is negligible. The overall grain number density is correlated linearly with the number densities of P and Cube（{001}？100？） grains. The grain number densities of typical orientations（P, ND-rotated cube {001}？310？ and Cube） and the overall recrystallized grains increase as rolling strain increases, following a similar exponential law.

关键词： recrystallisation texture aluminium alloys particle-stimulated nucleation EBSD

Combined effect of deformation and artificial aging on mechanical properties of Al-Mg-Si Alloy

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Transactions of Nonferrous Metals Society of China 2012年第8期22卷 1824-1830页

作者： Michal KOLAR Ketill Olav PEDERSEN Sverre GULBRANDSEN-DAHL knut MARTHINSEN Department of Materials Science and Engineering Norwegian University of Science and TechnologyNO-7491TrondheimNorway SINTEF Materials and Chemistry NO-7465TrondheimNorway SINTEF Raufoss Manufacturing AS NO-2831 RaufossNorway

The effect of pre-deformation followed by or together with artificial aging on the mechanical properties as strength and ductility of an AA6060 aluminium alloy was studied. AA6060 was initially cast, homogenized and extruded according to standard industrial practice. The extruded material was then subjected to a solution heat treatment and subsequently artificial aging after （sequential mode） and during （simultaneous mode） various combinations of deformation （0-10%） and heat treatments. The aging behaviour and mechanical properties were characterized in terms of Vickers hardness and tensile testing. It is found that precipitation kinetics and associated mechanical response, in terms of hardness and tensile properties are strongly affected by pre-deformations. In terms of aging behaviour, kinetics is accelerated and the peak strength generally increases. Comparing sequential mode and simultaneous mode, the latter seems to give overall better mechanical properties and after considerably shorter aging times. The results of the two modes of pre-deformation are compared and discussed in view of differences in processing conditions and microstructure characteristics.

关键词： Al-Mg-Si alloys artificial aging pre-deformation tensile properties

Evolution in microstructure and mechanical properties during back-annealing of AlMnFeSi alloy

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Transactions of Nonferrous Metals Society of China 2012年第8期22卷 1878-1883页

作者：王宁 Jarl Erik FLATφY 李彦军 knut MARTHINSEN Department of Materials Science and Engineering Norwegian University of Science and TechnologyNO-7491TrondheimNorway SINTEF Materials and Chemistry NO-7465TrondheimNorway

An Al-Mn-Fe-Si model alloy was subjected to two homogenization treatments, to achieve materials with different levels of Mn in solid solution and dispersoid densities, followed by cold rolling and back-annealing. Characterization of homogenization and deformation structures with respect to the effect of different microchemistries and strains on the structures was performed. Time-temperature-transformation （TTT） diagram with respect to precipitation and recrystallisation as a basis for analysis of the degree of concurrent precipitation was established. The TTT-diagram shows a strong effect of Mn concentration in solid solution and dispersoid density on the softening behavior. Recrystallization which finishes without the effect of concurrent precipitation results in an even, fine and equiaxed grain structure. Precipitation prior to or during recrystallization （concurrent） does retard the softening kinetics and leads to a coarse grain structure. However, the effect also depends on the duration of recrystallization and amount of precipitation. Recrystallization proceeding over a long time combined with a large amount of concurrent precipitation has a strong effect, otherwise the effect will be limited. Pre-existing fine and dense dispersoids （mean size 0.1 μm） before back-annealing do also lead to a coarse grain structure after recrystallization no matter whether additional concurrent precipitation occurs.

关键词： homogenization treatment dispersoid phase solid solution back-annealing recrystallization concurrent precipitation TTT-diagram

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

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Frontiers of Environmental Science & Engineering 2009年第2期3卷 226-235页

作者： Fangyue LI Joachim BEHRENDT knut WICHMANN Ralf OTTERPOHL Institute of Water Resources and Water Supply Hamburg University of TechnologySchwarzenbergstr.95 ED-21073 HamburgGermany Department of Wastewater Management Hamburg University of TechnologyEissendorfer Strasse 42D-21073 HamburgGermany

In this study,a mathematical model was established to predict the formation of the soluble microbial product(SMP)in a submerged membrane *** developed model was calibrated under the reference *** results were in good agreement with the measured results under the reference *** calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters:hydraulic retention time(HRT),dissolved oxygen concentration,and sludge retention time(SRT).Simulation results revealed that the SMP dominated the soluble organic substances in the *** scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality;dissolved oxygen concentration in the reactor can be kept at 2–3 mg/L to maintain the effluent quality,reduce the content of SMP,and minimize operating costs;the optimal SRT can be controlled to 10–15 d to achieve complete nitrification process,less membrane fouling potential,and acceptable organic removal efficiency.

关键词： hybrid activated sludge model(ASM) membrane bioreactor(MBR) soluble microbial product(SMP)

Postoperative ileus: Impact of pharmacological treatment,laparoscopic surgery and enhanced recovery pathways

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World Journal of Gastroenterology 2010年第17期16卷 2067-2074页

作者： knut Magne Augestad Conor P Delaney Division of Colorectal Surgery University Hospitals Case Medical CenterClevelandOH 44106-5047United States Department of Digestive Surgery Telemedicine and Integrated CareUniversity Hospital North Norway9037 TromsφNorway

Almost all patients develop postoperative ileus (POI) after abdominal *** represents the single largest factor influencing length of stay (LOS) after bowel resection,and has great implications for patients and resource utilization in health *** methods to treat and decrease the length of POI are therefore of great *** the past decade,a substantial amount of research has been performed evaluating POI,and great progress has been made in our understanding and treatment of *** procedures,enhanced recovery pathways and pharmacologic treatment have been *** factor has substantially contributed to decreasing the length of POI and thus LOS after bowel *** editorial outlines resource utilization of POI,normal physiology of gut motility and pathogenesis of *** treatment,fast track protocols and laparoscopic surgery can each have significant impact on pathways causing *** optimal integration of these treatment options continues to be assessed in prospective studies.

关键词： Postoperative ileus Pathophysiology Cost utilization Pharmacologic treatment Laparoscopic surgery Enhanced recovery pathways

Alcohol consumption in patients with primary sclerosing cholangitis

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World Journal of Gastroenterology 2012年第24期18卷 3105-3111页

作者： Hannes Hagstrm Per Stl knut Stokkeland Annika Bergquist Department of Gastroenterology and Hepatology Karolinska University HospitalKarolinska Institutet14186 StockholmSweden Department of Medicine Visby HospitalKarolinska Institutet14186 StockholmSweden

AIM:To assess the alcohol drinking patterns in a cohort of primary sclerosing cholangitis(PSC) patients and the possible influence on the development of ***:Ninety-six patients with PSC were evaluated with a validated questionnaire about a patient's lifetime drinking habits:the lifetime drinking history(LDH) *** addition,clinical status,transient elastography and biochemistry values were analysed and *** were defined as having either significant or non-significant *** fibrosis was defined as either an elastography value of ≥ 17.3 kPa or the presence of clinical signs of *** were divided into two groups depending on their alcohol consumption patterns;no/low alcohol consumption(one drink or unit/d) and moderate/high alcohol consumption(≥ 1 drink or unit/d).LDH data were calculated to estimate lifetime alcohol intake(LAI),current alcohol intake,drinks per year before and after diagnosis of *** also calculated the number of episodes of binge-drinking(defined as consuming ≥ 5 drinks per occasion) in total,before and after the diagnosis of ***:The mean LAI was 3882 units of alcohol,giving a mean intake after onset of alcohol consumption of 2.6 units per *** 9% of patients consumed alcohol equal to or more than one unit per *** alcohol intake in patients with significant fibrosis(n = 26) was less than in patients without significant fibrosis(n = 70),as shown by lower values of phosphatidylethanol(B-PEth)(0.1 mol/L vs 0.33 mol/L,respectively,P = 0.002) and carbohydrate-deficient transferrin(CDT)(0.88% vs 1.06%,respectively,P = 0.02).Self-reported LAI was similar between the two *** with significant fibrosis reduced their alcohol intake after diagnosis from 103 to 88 units per year whereas patients without fibrosis increased their alcohol intake after PSC diagnosis from 111 to 151 units/*** were no correlations between elastography values and intake of alcoho

关键词： Alcohol Fibrosis Cirrhosis Lifetime drinkinghistory Primary sclerosing cholangitis