scholarly journals Syntactic Annotation in the I3rab Dependency Treebank

2021 ◽  
Vol 18 (3A) ◽  
Author(s):  
Dana Halabi ◽  
Arafat Awajan ◽  
Ebaa Fayyoumi
Keyword(s):  
Poor Performance ◽  
Coarse Grained ◽  
Fine Grained ◽  
Overall Performance ◽  
Dependency Relations ◽  
Syntactic Annotation ◽  
Dependency Parser ◽  
The Impact

Arabic dependency parsers have a poor performance compared to parsers of other languages. Recently the impact of annotation at lexical level of dependency treebank on the overall performance of the dependency parses has been extensively investigated. This paper focuses on the impact of coarse-grained and fine-grained dependency relations on the performance of Arabic dependency parsers. Moreover, this paper introduces the annotation rules for I3rab dependency treebank. Experimentally, the obtained results showed that having an appropriate set of dependency relations improves the performance of an Arabic dependency parser up to 27.55%.

scholarly journals Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1215 ◽  
Author(s):  
Gorazd Lojen ◽  
Tomaž Vuherer
Keyword(s):  
Impact Toughness ◽  
Elevated Temperatures ◽  
Thermal Power ◽  
Post Weld Heat Treatment ◽  
Coarse Grained ◽  
Target Range ◽  
Fine Grained ◽  
Creep Resistant Steels ◽  
The Impact ◽  
Weld Heat

Appropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat affected zone (HAZ) subzones was studied. Thereby, coarse grained HAZ, two different fine grained HAZ areas, and intercritical HAZ were subjected to 20 different PWHTs at temperatures 740–800 °C and durations 0.5–8 h. It was found that the most commonly recommended PWHT, of 3 h or less at 760 °C, is insufficient with respect to the hardness and impact toughness of coarse grained HAZ. To obtain a Vickers hardness ≤ 265 HV and impact toughness at least equal to the impact toughness of the base metal (192 J) in the coarse grained HAZ, it took 8 h at 740 °C, 4 h at 760 °C, more than 1 h at 780 °C, and 0.5 h and 800 °C. Even after 8 h at 800 °C, mechanical properties were still within the target range. The most recommendable post weld heat treatments at 780 °C for 1.2–2 h or at 760 °C for 3–4 h were identified. All specimens subjected to these treatments exhibited appropriate hardness, impact toughness, and microstructure.

The critical influence of La content on the microstructure-toughness relationship in the simulated coarse-grained heat-affected zone of high-strength low-alloy steels

2021 ◽  
Vol 118 (2) ◽  
pp. 212
Author(s):  
Yuxin Cao ◽  
Xiangliang Wan ◽  
Feng Zhou ◽  
Hangyu Dong ◽  
Kaiming Wu ◽  
...  
Keyword(s):  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
High Strength ◽  
Coarse Grained ◽  
Low Alloy Steels ◽  
Fine Grained ◽  
Welding Thermal Cycle ◽  
Alloy Steels ◽  
High Fraction ◽  
The Impact

The present study was envisaged to investigate the role of La content on the particle, microstructure and toughness in the simulated coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steels. Three steels with La content of 0.016 wt.%, 0.046 wt.% and 0.093 wt.% were prepared and simulated in a 100 kJ/cm heat input welding thermal cycle. Subsequently, the particle and microstructure of selected specimens were characterized and the impact absorb energy was measured at −20 °C. The results indicated that the La2O2S inclusions in 0.016 wt.%-La steel were gradually modified to LaS-LaP in 0.046 wt.%-La steel and to LaP in 0.093 wt.%-La steel. A higher fraction of acicular ferrite was obtained in the simulated CGHAZ of 0.016 wt.%-La steel, since the inclusion of La2O2S was more powerful to induce the formation of acicular ferrite. Furthermore, the fraction of M-A constituents in the simulated CGHAZ increased with increasing La content. The impact toughness in the simulated CGHAZ of 0.016 wt.%-La steel was the highest, owing to the high fraction of the fine-grained acicular ferrite and low fraction of M-A constituent.

The Impact of Grain Size on Oxidation Behavior of TP304H Austenitic Stainless Steel at High Temperature in Air

2011 ◽  
Vol 117-119 ◽  
pp. 990-994
Author(s):  
Wei Wei ◽  
Zhi Wu Wang ◽  
Mao Lin Liu
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Oxide Scale ◽  
Grain Refinement ◽  
Coarse Grained ◽  
X Ray ◽  
Fine Grained ◽  
Different Grain Size ◽  
The Impact

Exposed to 650°C air, TP304H stainless steel with two different grain size was oxidized at this temperature. At the meantime, comparison of their oxidation was through the oxidation kinetics curves and analysis of the morphology and composition of oxide scale which conducted by SEM and X-ray. The results showed that the oxidation rate of TP304H stainless steel was slowed down by grain refinement and oxide scale of fine-grained TP304H steel was thinner than that of coarse-grained steel. The nucleation and the growth of nuclei of coarse-grained oxide scale were more rapid. In addition, the grain refinement of austenitic stainless steel accelerated the diffusivity of Cr and made for the formation of dense and continuous oxide scale, so that the oxidation of stainless steel can be effectively inhabited.

scholarly journals Luminescence properties and dating of glacial to periglacial sediments from northern Switzerland

Geochronology ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 305-323
Author(s):  
Daniela Mueller ◽  
Frank Preusser ◽  
Marius W. Buechi ◽  
Lukas Gegg ◽  
Gaudenz Deplazes
Keyword(s):  
Thermal Quenching ◽  
Systematic Investigation ◽  
Swiss Alps ◽  
Luminescence Dating ◽  
Coarse Grained ◽  
Luminescence Properties ◽  
Northern Switzerland ◽  
Fine Grained ◽  
The Impact ◽  
Partial Bleaching

Abstract. Luminescence dating has become a pillar of the understanding of Pleistocene glacial advances in the northern foreland of the Swiss Alps. However, both quartz and feldspar from the region are equally challenging as dosimeters with anomalous fading and partial bleaching being some of the obstacles to overcome for the establishment of decisive chronologies. In this study, luminescence properties of coarse- and fine-grained quartz, feldspar, and polymineral fractions of eight samples from a palaeovalley, Rinikerfeld in northern Switzerland, are systematically assessed. Standard performance tests are conducted on all four fractions. Deconvolution of luminescence signals of the quartz fractions is implemented and shows the dominance of stable fast components. Reader-specific low preheat temperatures are investigated on the infrared stimulated luminescence (IRSL) signal of feldspar. Thermal stability of this signal is found for low preheats, and thermal quenching could be excluded for higher preheats. However, anomalous fading is observed in the feldspar and polymineral IRSL signals and two correction approaches are applied. For one approach, fading corrected coarse-grained feldspar ages are consistent with those derived from quartz. In general, coarse-grained quartz and feldspar, as well as the fine-grained polymineral fraction of one sample, are in chrono-stratigraphic agreement and present negligible evidence for partial bleaching. However, ages derived from fine-grained quartz are found to underestimate those of the coarse-grained quartz fractions. Hence, the impact of alpha efficiency and water content on the dose rate and thus the ages are assessed. A finite explanation for the observed discrepancies remains lacking, but this systematic investigation of different luminescence signals allows for the establishment of a chronology for the palaeovalley fill dating back to at least Marine Isotope Stage 6 (MIS 6).

scholarly journals Effect of Ferritic Morphology on Yield Strength of CGHAZ in a Low Carbon Mo-V-N-Ti-B Steel

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1863
Author(s):  
Leping Wang ◽  
Huibing Fan ◽  
Genhao Shi ◽  
Qiuming Wang ◽  
Qingfeng Wang ◽  
...  
Keyword(s):  
Yield Strength ◽  
Heat Input ◽  
Low Carbon Steel ◽  
High Heat ◽  
Coarse Grained ◽  
Granular Bainite ◽  
Low Carbon ◽  
Fine Grained ◽  
High Heat Input ◽  
The Impact

For investigating the impact of ferritic morphology on yield strength (YS) of the high-heat-input welding induced coarse-grained heat-affected zone (CGHAZ) of a low carbon Mo-V-N-Ti-B steel, a group of particular welding heat inputs were designed to obtain different ferritic microstructures in CGHAZ. The tensile properties were estimated from typical samples with ferritic microstructures. The mixed microstructures dominated by the intragranular polygonal ferrite (IGPF), the intragranular acicular ferrite (IGAF), and the granular bainite (GB) were obtained at the heat inputs of 35, 65, 85 and 120 kJ/cm, respectively. When the main microstructure changed from IGPF to IGAF and GB, YS increased first and then decreased. The microstructure consisting mainly of IGAF possessed the maximum YS. As the main microstructure changed from IGPF to IGAF and GB, the contribution of grain refinement strengthening to YS was estimated to be elevated remarkably. This means the strength of CGHAZ in a low-carbon steel subjected to the high-heat-input welding could be enhanced by promoting the fine-grained AF and GB formation.

scholarly journals Investigation of the heat-affected zone fracture in Ni3Al welds

1992 ◽  
Vol 7 (5) ◽  
pp. 1076-1082 ◽  
Author(s):  
G.H. Chen ◽  
C. Chen
Keyword(s):  
Heat Affected Zone ◽  
Postweld Heat Treatment ◽  
Coarse Grained ◽  
Transgranular Fracture ◽  
Slow Cooling ◽  
Fine Grained ◽  
Boron Segregation ◽  
Ductile Mode ◽  
Fracture Appearance ◽  
The Impact

Ternary Ni77Al23−yXy (X = Zr or Hf, y = 0.5 or 1) + 500 ppm boron compounds with various grain sizes were welded by a CO2 laser. Fractographic examinations of the heat-affected zone (HAZ) in the welds with or without postweld heat treatment (PWHT) were performed on the impact-fractured specimens. In laser welds, the fracture appearance of the HAZ was mixed transgranular/intergranular modes for fine-grained alloys and intergranular mode for coarse-grained materials. However, an entirely transgranular mode was observed in the base metal regardless of the grain size of the compounds. Boron desegregation at high temperatures during the thermal cycle of welding could be used to explain the fractographic change from originally ductile mode into less-ductile or even brittle fracture in the HAZ. Short-term PWHTs along with slow cooling provided sufficient time for boron segregation back to the grain boundary, resulting in a completely transgranular fracture mode in the fine-grained HAZ. Nevertheless, such a phenomenon was not observed in the HAZ of coarse-grained welds. Cracks in the HAZ of coarse-grained welds after long-term PWHT, if not so severe, could be healed by a sintering process.

Effect of Microstructure on Impact Energy of an Al-Mg-Sc Alloy

2016 ◽  
Vol 877 ◽  
pp. 421-426
Author(s):  
Daria Zhemchuzhnikova ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Impact Toughness ◽  
Impact Energy ◽  
Coarse Grained ◽  
Fine Grained ◽  
Angular Pressing ◽  
Average Grain Size ◽  
Coarse Grained State ◽  
Hot Rolled ◽  
The Impact

Analysis of the absorbed impact energy of an Al-Mg-Sc alloy after different thermo-mechanical processing routes was investigated between-196°C and 20°C. The material with a grain size of ∼ 22 μm in cast condition and with an average grain size of 0.7 μm produced by was produced by equal-channel angular pressing (ECAP) exhibits well-defined ductile-brittle transition in the temperature interval-60...-100°C, however, even at-196°C the value impact energy of fine-grained alloy is higher by a factor of 2 in comparison with coarse-grained state. The impact toughness of the hot rolled alloy linearly decreases with decreasing temperature. The influence of different microstructures on impact toughness and fracture behavior of alloy is discussed.

Microstructure and mechanical properties of fine-grained iron processed by hydroextrusion

2012 ◽  
Vol 57 (3) ◽  
pp. 883-887 ◽  
Author(s):  
B. Romelczyk ◽  
M. Kulczyk ◽  
Z. Pakieła
Keyword(s):  
Mechanical Properties ◽  
Impact Test ◽  
Armco Iron ◽  
Hydrostatic Extrusion ◽  
Coarse Grained ◽  
Consolidation Process ◽  
Iron Powders ◽  
Fine Grained ◽  
Cumulative Strain ◽  
The Impact

The aim of this study was to characterize the microstructure and properties of fine-grained iron. The samples were prepared by sintering at 1000°C ±5°C for 30 minutes, followed by Severe Plastic Deformation via Hydrostatic Extrusion (HE). After the sintering the rod samples were capsulated to prevent damage during extrusion. HE has been applied as a final consolidation process of iron powders. The HE process was carried out on two extrusion passes. The rods of 8 mm in diameter were obtained as a final product after hydroextrusion. The total cumulative strain was 2.3. Materials in three states were investigated: sintered, sintered and deformed by one hydrostatic extrusion pass, and two hydrostatic extrusion passes. The results were compared with the results obtained for coarse-grained Armco iron. The measurements showed that the grain size was reduced from 3.5 μm after sintering to 180±81 nm after the 2nd extrusion pass. The tensile strength and microhardeness increased with cumulative strain of the material. The impact test carried out at -196°C showed transformation of the fracture mechanism from cleavage for coarse-grained structure to ductile for extruded material. W pracy scharakteryzowano mikrostrukture i mechaniczne własciwosci ultradrobnoziarnistego spieku zelaza. Próbki przygotowano w dwóch etapach - wypraski spieczono w temperaturze 1000°C ±5°C w czasie 30 minut, a nastepnie spieki odkształcono metoda wyciskania hydrostatycznego [HE]. W celu unikniecia pekania spieków proces wyciskania przeprowadzono na próbkach uprzednio zakapsułkowanych. Proces HE przebiegał w dwóch etapach a skumulowane odkształcenie wyniosło 2.3. srednica koncowego produktu wyniosła 8 mm. W pracy przedstawiono wyniki badan zarówno spieku, jak i materiału po poszczególnych wyciskaniach hydrostatycznych. Wyniki badan ujawniły redukcje rozmiaru ziaren zelaza z 3.5 μm po spiekaniu do 180 nm po drugim wyciskaniu HE. Zarówno wytrzymałosc ja i mikrotwardosc wzrosły ze stopniem skumulowanego odkształcenia próbek. Wyniki badan udarnosciowych porównano z wynikami otrzymanymi dla gruboziarnistego zelaza Armco. Badania udarnosci metoda Charpiego przeprowadzono na próbkach uprzednio chłodzonych w ciekłym azocie. Obserwacje mikroskopowe przełomów próbek po udarnosci wykazały zmiane charakteru pekania zelaza z łupliwego dla materiału gruboziarnistego na ciagliwy dla materiału ultradrobnoziarnistego.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

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