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81.
AbstractIn this study, the 0.2% yield stress of duplex stainless steel was evaluated using a compound Hall–Petch equation. The compound Hall–Petch equation was derived from four types of duplex stainless steel, which contained 0.2–64.4 wt% δ-ferrite phase, had different chemical compositions and were annealed at different temperatures. Intragranular yield stress was measured with an ultra-microhardness tester and evaluated with the yield stress model proposed by Dao et al. Grain size, volume fraction and texture were monitored by electron backscattering diffraction measurement. The kγ constant in the compound equation for duplex stainless steel agrees well with that for γ-phase SUS316L steel in the temperature range of 1323–1473 K. The derived compound Hall–Petch equation predicts that the yield stress will be in good agreement with the experimental results for the Cr, Mn, Si, Ni and N solid-solution states. We find that the intragranular yield stress of the δ-phase of duplex stainless steel is rather sensitive to the chemical composition and annealing conditions, which is attributed to the size misfit parameter. 相似文献
82.
D. Fink M. Müller P. Szimkowiak M. Döbeli A. Spieler M. Grether 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):911-962
Abstract Thin fullerite films - partly covered with a thin Au layer -have been irradiated with 100 keV Arn+ (n = 1, 6, and 12), 250 keV N+, and 30 keV Au+ ions up to high fluences, and subsequently analyzed by profilometry, Rutherford Backscattering Spectrometry (RBS), and Atomic Force Microscopy (AFM). Depending on the system, either an increase or a decrease of the film thickness after the irradiations was found, and the probing RBS α particles suffered sometimes an enhanced, and sometimes a reduced energy loss upon passage through the films. The comparison of profilometry and RBS results on uncovered and covered samples allows us to separate the different effects which influence the behavior of high-fluence irradiated fullerite samples clearly from each other. Such effects might be the incorporation of the projectile ions, density changes, phase changes, sputtering, and transport of neighbored unirradiated matter into the irradiated zone. It is remarkable that ion irradiation of fullerite can lead as well to a densified material, with densities of about 2.1 g-cm?3, as to a foam-like carbonaceous material with a density around 0.35 g-cm?3 - depending on the type of projectile and its range. The latter case appears to be characteristic for high-fluence heavy noble gas implantation into fullerite. Fullerite sputtering was reconfirmed to decrease inversely with the fluence. 相似文献
83.
为了分析水下激光成像探测系统的探测能力,根据水下蓝绿激光主动成像系统的成像过程,分析了目标与背景的辐射特性、海水后向散射特性、距离选通特性以及激光发射器和接收器的性能,提出了一种基于光束扩展函数(BSF)的探测灵敏度模型。该模型在海水散射系数与衰减系数之比介于0~1的范围内都适用。通过对给定参数的系统进行分析计算,进一步讨论了激光发散角、系统接收口径和图像传感器选通门宽等因素对系统探测能力的影响。结果表明:当选通门宽等于激光脉冲宽度时,系统的探测深度达到最大。模型的建立将为系统设计和系统参量的优化选择提供理论依据。 相似文献
84.
W-Ping Xu Lirong Zheng Chenglu Lin Masanori Okuyama 《Integrated ferroelectrics》2013,141(2-4):233-239
Abstract Barium titanate (BaTiO3) thin films with high (111)-orientation were successfully grown on TiO2-covered Si(111) substrate using hydrothermal method, where the TiO2 layer was previously fabricated at room temperature by means of ion-beam-assisted deposition. This processing method provides a simple mild-chemical route for directly producing the analogous crystalline films on different substrates. The BaTiO3 films did not reach the TiO2/Si interface even if the hydrothermal treatment was prolonged to 24 hours. Both Rutherford backscattering and spread-resistance profiling characterizations confirmed the diffusion nature of the formed Ba-TiO3/TiO2/Si system. 相似文献
85.
研究一种基于分布式光纤振动传感原理和电缆局部放电原理的电力电缆故障定位技术.通过在电缆上施加高压脉冲,使得电缆上有故障的位置产生局部放电,从而产生振动信号.并将放电脉冲信号同步传输给分布式光纤振动监测系统.通过分布式光纤振动传感技术来探测电缆沿线放电产生的振动信号,并对振动信号进行定位.将该故障定位技术应用于电力电缆沿线上监测电缆故障的状态分布,并进行试验验证.实验结果表明,该系统可实现监测多回路30 km电缆线路的故障分布状况,并对故障点进行准确定位. 相似文献
86.
使用EBSD研究了AA6111合金在两次热轧过程中不同保持时间对晶体织构演变的影响.结果显示:变形织构主要由α和β纤维组成.从主要织构组分的取向强度看出,随着保持时间的增加,Brass和Copper理想织构组分显著增加,S织构没有明显变化. 相似文献
87.
Microstructure and Residual Stress Formation in Induction‐Assisted Laser Welding of the Steel S690QL
Steels of high mechanical strength combined with high toughness, such as those in quenched and tempered condition are required to reduce weight in industrial machinery. Their mechanical performance is impaired by welding operations which often cause a reduction of toughness and increase the probability for cold cracking due to martensite formation in the weld seam. The limited weldability of high‐strength steels therefore demands appropriate joining procedures to increase their use in industrial construction and reduce reworking costs. Induction heating is capable of directly producing heat inside a work piece. This enables the integration of induction heat‐treatments into serial welding processes. In this work, the effect of induction‐assisted laser welding on the microstructure and residual stresses in S690QL butt joints was investigated. The results reveal that conventional laser welding causes strong martensite formation in the weld seam and the heat‐affected zone. This leads to prohibitive hardness values. Induction heat‐treatments result in an efficient reduction of hardness in the fusion zone. However, the efficiency decreases with increasing sheet thicknesses. The residual stress distributions after laser welding with and without induction heating are typical of fusion welding. Although an effective reduction of hardness is achieved by induction‐assisted laser welding, the residual stresses remain significantly high. 相似文献
88.
89.
90.
本文研究金属目标的后向散射特性与入射角、表面温度场之间的关系。根据现有条件设计了实验装置,并用该装置测量了部分实验数据。相关结论对激光探测等领域的研究具有一定的参考价值。 相似文献