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磷元素在钢中的晶界偏聚 总被引:5,自引:0,他引:5
磷元素在钢中的晶界偏聚可以分为两类,即平衡偏聚和非平衡偏聚.介绍了这两类偏聚现象以及偏聚理论.以磷对晶界结合力、晶界扩散和晶界能的影响机理为基础,分析了磷元素对钢力学性能的影响和磷在钢中发生晶界偏聚的原因. 相似文献
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Genichi Shigesato Taishi Fujishiro Takuya Hara 《Metallurgical and Materials Transactions A》2014,45(4):1876-1882
The boron concentration profiles around prior austenite grain boundaries in Fe-0.05C-0.5Mo-0.001B (mass pct) are examined using aberration-corrected STEM-EELS. In order to obtain the precise distribution of boron around the boundaries, tilt series measurements with thin specimens (<30 nm) are performed and the EEL spectra are analyzed by principal component analysis (PCA) and multivariate curve resolution (MCR). The boron concentration profile changes with the cooling rate from the solid solution temperature. The concentration at grain boundaries is maximized at a medium rate (30 °C/s), where the concentration reaches 8 at. pct, and it decreases at a larger (250 °C/s) or smaller (5 °C/s) rate. On the other hand, the boron distribution becomes wider as the cooling rate becomes smaller. The current results suggest that the boron segregation in the alloy is formed by the “non-equilibrium segregation mechanism.” 相似文献
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研究了二次硬化超高强度AF1410钢(%:0.165C、14.10Co、9.83Ni、1.92Cr、1.05Mo)在800~1200℃ 5~180 min加热的奥氏体晶粒长大行为。结果表明,AF1410钢奥氏体平均晶粒尺寸随加热温度的升高和保温时间延长而增大,加热温度超过1100℃后,奥氏体晶粒发生严重粗化;不同加热温度下,该钢的奥氏体平均晶粒尺寸与保温时间符合Beck关系;建立了AF1410钢的奥氏体晶粒长大数学模型,800~1200℃加热时,该钢奥氏体晶粒长大平均激活能为220.2 kJ/mol,其奥氏体平均晶粒尺寸与加热温度之间符合Arrhenius关系。 相似文献
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Eun Yoo Yoon Dong Jun Lee Lee Ju Park Sunghak Lee Mohamed Ibrahim Abd El Aal Hyoung Seop Kim 《Metallurgical and Materials Transactions A》2014,45(11):4748-4752
High tensile strength of 616 MPa and improved ductility of 7.6 pct were obtained in powder-consolidated pure Cu processed by high-pressure torsion (HPT) at room temperature followed by post-annealing at 673 K (400 °C). The powder-HPT consolidation process maintained nano-crystalline microstructures even after post-annealing due to the presence of well-dispersed oxide particles in the matrix. Higher ductility in the post-annealed specimen is attributed to higher fraction of stable Σ3 coincidence site lattice boundaries than that in the HPT-processed Cu. 相似文献
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Vadim Shterner Ilana B. Timokhina Anthony D. Rollett Hossein Beladi 《Metallurgical and Materials Transactions A》2018,49(7):2597-2611
In the current study, the dependence of mechanical twinning on grain orientation and grain boundary characteristics was investigated using quasi in-situ tensile testing. The grains of three main orientations (i.e., 〈111〉, 〈110〉, and 〈100〉 parallel to the tensile axis (TA)) and certain characteristics of grain boundaries (i.e., the misorientation angle and the inclination angle between the grain boundary plane normal and the TA) were examined. Among the different orientations, 〈111〉 and 〈100〉 were the most and the least favored orientations for the formation of mechanical twins, respectively. The 〈110〉 orientation was intermediate for twinning. The annealing twin boundaries appeared to be the most favorable grain boundaries for the nucleation of mechanical twinning. No dependence was found for the inclination angle of annealing twin boundaries, but the orientation of grains on either side of the annealing twin boundary exhibited a pronounced effect on the propensity for mechanical twinning. Annealing twin boundaries adjacent to high Taylor factor grains exhibited a pronounced tendency for twinning regardless of their inclination angle. In general, grain orientation has a significant influence on twinning on a specific grain boundary. 相似文献
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The grain boundary character distribution in a commercial IF steel has been measured as a function of lattice misorientation and boundary plane orientation. The grain boundary plane distribution revealed a relatively low anisotropy with a tendency for grain boundaries to terminate on low index planes having relatively low surface energy and large interplanar spacings. Although the most common grain boundary plane orientation was (111), grain boundaries terminated on higher index planes were sometimes found. For instance, at a misorientation angle of 60?deg about [111], symmetric {112} tilt boundaries were far more populous than [111] twist boundaries. The current observation revealed an inverse relationship between the measured populations and the previously reported grain boundary energies. 相似文献
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Zhong-ping SHI Zhen-hua WANG Shu-hua SUN Ze-an ZHOU Ying-ping GUAN Wan-tang FU 《钢铁研究学报(英文版)》2014,21(10):945-950
The phase diagram of an Nb- and V-containing 18Mnl8Cr0.5N steel was investigated using thermodynam ic calculation. The compositions and characteristics of precipitates were investigated by scanning electron microsco- py, energy dispersive spectrometry, X-ray diffraction, and differential scanning calorimetry. Under equilibrium con- ditions, MX precipitates at 1 350 ℃. MX is a substitutional solid solution of Nb4 N3.38, and its composition (at. %) is approximately.. Nb 40, N 40, V 8, and Fe, Cr, and Mn balance. The precipitates, with shapes including irregular bulk, rod, and ellipsoid, are primarily distributed at grain boundaries and triple junctions, and their size is approxi- mately 5 10 μm. Finally, the microalloying of high nitrogen CrMn austenite steels, control of precipitate size, and the effect of precipitate on hot formin~ were discussed. 相似文献
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Grain refinement is one of the successful and low-cost methods to develop metals having excellent combination of strength and ductility. Low carbon steel was deformed by using multidirectional forging (MDF) technique at room temperature. The influence of strain amount and annealing process on the microstructure and mechanical properties of investigated steel was studied. The grain refinement mechanism was studied by the microstructure observation. The results showed that the grain refinement was attained by multidirectional forging technique. The initial coarser grains of average 38 μm size fragmented into very fine ferrite with grain sizes of about 1.2 μm. After MDF, the strength properties improved significantly, although uniform elongation and elongation decreased with increasing strain. 相似文献
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Beladi Hossein Torbati-Sarraf Hamidreza Rohrer Gregory S. Poorganji Behrang Torbati-Sarraf Seyed Alireza 《Metallurgical and Materials Transactions A》2022,53(10):3749-3758
Metallurgical and Materials Transactions A - Commercially pure Ni was additively manufactured using laser powder bed fusion. The printed specimens were then subjected to annealing treatments in a... 相似文献
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S. DowneyII K. Han P.N. Kalu K. Yang Z.M. Du 《Metallurgical and Materials Transactions A》2010,41(4):881-887
This article reports our efforts in characterization of an ultralow carbon 316LN-type stainless steel. The carbon content
in the material is one-third that in a conventional 316LN, which further inhibits the formation of grain boundary carbides
and therefore sensitizations. Our primary effort is focused on characterization of submicron size precipitates in the materials
with the electron backscatter diffraction (EBSD) technique complemented by Auger electron spectroscopy (AES). Thermodynamic
calculations suggested that several precipitates, such as M23C6, Chi, Sigma, and Cr2N, can form in a low carbon 316LN. In the steels heat treated at 973 K (700 °C) for 100 hours, a combination of EBSD and AES
conclusively identified the grain boundary precipitates (≥100 nm) as Cr2N, which has a hexagonal closed-packed crystallographic structure. Increases of the nitrogen content promote formation of
large size Cr2N precipitates. Therefore, prolonged heat treatment at relatively high temperatures of ultralow carbon 316LN steels may result
in a sensitization. 相似文献
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Itiswellknownthatthestrain inducedtrans formationfromaustenitetoferritecanleadtograinrefinement .Thushighermechanicalpropertiessuchasstrengthandductilitycanbeobtained[1,2 ] .Someresearcheshavebeencarriedoutonthenucleationofstrain inducedferriteinthepastyears .PDHodgsonetalsuggestedthattheaustenitegrainsshouldbeascoarseaspossibletodecreasenucleationatgrainbo undaries[3 ] .PJHurleyetalconsideredthatthecel lularboundaryofdislocationsuppliesthesitesfornu cleationofstrain inducedferrite[4] .Yang… 相似文献
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R. Shukla S. K. Das B. Ravi Kumar S. K. Ghosh S. Kundu S. Chatterjee 《Metallurgical and Materials Transactions A》2012,43(12):4835-4845
In the current study, a novel ultra-low carbon, high-molybdenum-bearing microalloyed steel has been thermomechanically processed. Transformation of this steel during continuous cooling has been assessed. Variation in the microstructure and mechanical properties at different finish rolling temperatures has been studied. The average grain size, misorientation of grain boundary, and distribution of ferrite grains have been analyzed by using electron backscatter diffraction. The lower yield strength (251 to 377?MPa) with moderate tensile strength (406 to 506?MPa) along with high ductility (30 to 47?pct) has been achieved in the selected range of finish rolling temperatures. Superior impact toughness value in the range of 153 to 162?J is obtained in the subsize specimen even at subzero temperatures (233?K [?40?°C]), which is attributed to fine average ferrite grain size. The acicular ferrite dominated microstructure obtained at the 1023?K (750?°C) finish rolling temperature is the most attractive microstructure for pipeline applications due to its excellent combination of strength and toughness. 相似文献