期刊文献+
共找到2,727篇文章
< 1 2 137 >
每页显示 20 50 100
基于FPGA的双DDS任意波发生器设计与杂散噪声抑制方法 被引量:79
1
作者 邓耀华 吴黎明 +1 位作者 张力锴 李业华 《仪器仪表学报》 EI CAS CSCD 北大核心 2009年第11期2255-2261,共7页
研究基于DDS(直接数字频率合成)的任意波信号产生的机理,在FPGA内嵌SOPC,配置了32位的软微处理器NiosII,利用FPGA实现双DDS的相位累加器,通过数字方法直接实现任意波形的各种频率调制。分析了高速相位累加器截断误差,幅度量化误差和D/A... 研究基于DDS(直接数字频率合成)的任意波信号产生的机理,在FPGA内嵌SOPC,配置了32位的软微处理器NiosII,利用FPGA实现双DDS的相位累加器,通过数字方法直接实现任意波形的各种频率调制。分析了高速相位累加器截断误差,幅度量化误差和D/A非线性引起的杂散分量产生的原因。推导出DDS相位噪声模型,针对信号的频谱成份设计了高阶低通滤波器对输出信号滤波。结合NiosII,设计硬件电路对输出信号进行幅频校正,保证了信号幅值的稳定输出及实际显示数值的一致性。测试表明,信号波形发生器能输出稳定、高带宽、高速度、高精度、低衰减的任意波形,三角波的输出频率大于1MHz,输出信号幅度峰峰值在50mV~20V范围内以10mV的步进调节。 展开更多
关键词 任意波发生器 SOPC 双DDS 相位截断 高阶滤波器 幅频校正
下载PDF
过时效对低碳Si-Mn双相钢性能和组织的影响 被引量:19
2
作者 朱晓东 王利 +1 位作者 季思凯 王聪 《材料热处理学报》 EI CAS CSCD 北大核心 2003年第2期50-54,共5页
研究过时效温度和时间对低碳Si Mn冷轧双相钢的力学性能和组织的影响 ,结果发现 ,过时效温度对双相钢力学性能影响很大。在 30 0℃以下 ,屈服强度和屈强比都较低 ,在 350℃以上 ,屈服强度和屈强比大大提高 ,并且出现了上下屈服现象。 3... 研究过时效温度和时间对低碳Si Mn冷轧双相钢的力学性能和组织的影响 ,结果发现 ,过时效温度对双相钢力学性能影响很大。在 30 0℃以下 ,屈服强度和屈强比都较低 ,在 350℃以上 ,屈服强度和屈强比大大提高 ,并且出现了上下屈服现象。 30 0~ 350℃之间是屈服强度急剧上升的温度。过时效时间对双相钢性能的也有较弱的类似影响。过时效温度上升仅造成双相钢中马氏体的相对量较小的下降 ,但对马氏体岛的形貌有较大影响 ,在较高过时效温度下的马氏体岛的分解 。 展开更多
关键词 冷轧 双相钢 过时效 力学性能 组织
下载PDF
双频金属探测器的研究 被引量:16
3
作者 庞瑞帆 钟翔 +3 位作者 胡泷 何云龙 徐毅刚 倪宏伟 《解放军理工大学学报(自然科学版)》 EI 2001年第2期1-8,共8页
用等效阻抗法分析了金属目标低频电磁感应信号幅度和相位特性 ,剖析了双频的理论基础和设计技术 ,论述了双频与探测灵敏度之间的关系 ,研究并设计了多层印制板接收线圈以及移相线圈 ,研究并解决了全自动抑制海水、磁性土等导电、导磁背... 用等效阻抗法分析了金属目标低频电磁感应信号幅度和相位特性 ,剖析了双频的理论基础和设计技术 ,论述了双频与探测灵敏度之间的关系 ,研究并设计了多层印制板接收线圈以及移相线圈 ,研究并解决了全自动抑制海水、磁性土等导电、导磁背景信号以及温度效应所引起的直流漂移的方法。 展开更多
关键词 双频 金属探测器 幅度 相位 直流漂移 等效阻抗法
下载PDF
中国余数定理在双基线InSAR相位解缠中的应用 被引量:20
4
作者 张红敏 靳国旺 +2 位作者 徐青 秦志远 孙伟 《测绘学报》 EI CSCD 北大核心 2011年第6期770-777,共8页
介绍利用中国余数定理求解同余方程组的基本公式,并将中国余数定理引入到双基线InSAR相位解缠中。构造关于干涉相位模糊数的同余方程组,设计基于中国余数定理的双基线InSAR相位解缠方法,扩展相位解缠的非模糊区间,为解决干涉相位欠采样... 介绍利用中国余数定理求解同余方程组的基本公式,并将中国余数定理引入到双基线InSAR相位解缠中。构造关于干涉相位模糊数的同余方程组,设计基于中国余数定理的双基线InSAR相位解缠方法,扩展相位解缠的非模糊区间,为解决干涉相位欠采样区域的相位解缠难题奠定基础。利用不同地区的多套DEM仿真的双基线InSAR干涉图进行相位解缠试验,验证该方法在干涉相位欠采样等区域的解缠能力。 展开更多
关键词 中国余数定理 合成孔径雷达干涉测量 多基线 双基线 相位解缠
下载PDF
多层螺旋CT双期扫描与生长抑素受体显像在胰腺内分泌肿瘤诊断中的比较 被引量:15
5
作者 王辉 李平 +1 位作者 潘卫东 薛华丹 《中国医学科学院学报》 CAS CSCD 北大核心 2016年第3期312-317,共6页
目的比较多层螺旋CT双期增强扫描与生长抑素受体显像(SRS)对胰腺神经内分泌肿瘤(p NET)诊断的敏感性。方法收集2012年5月至2015年1月在北京协和医院经病理确诊的28例p NET患者的临床资料,术前均行CT及SRS检查,分析并对比CT双期扫描及SRS... 目的比较多层螺旋CT双期增强扫描与生长抑素受体显像(SRS)对胰腺神经内分泌肿瘤(p NET)诊断的敏感性。方法收集2012年5月至2015年1月在北京协和医院经病理确诊的28例p NET患者的临床资料,术前均行CT及SRS检查,分析并对比CT双期扫描及SRS对p NET的诊断能力。结果 CT双期扫描和SRS对p NET患者总的诊断敏感性分别为92.8%(26/28)和71.4%(20/28),差异有统计学意义(P=0.031)。对功能性p NET患者的诊断敏感性分别为94.1%(16/17)和58.8%(10/17),差异无统计学意义(P=0.218);对无功能性p NET患者的诊断敏感性分别为90.9%(10/11)和90.9%(10/11),差异无统计学意义(P=0.740)。对无转移p NET患者的诊断敏感性分别为90.4%(19/21)和57.1%(12/21),差异无统计学意义(P=0.125);对合并转移p NET患者的诊断敏感性分别为100%(7/7)和100%(7/7)。对G1级患者的诊断敏感性分别为84.6%(11/13)和53.8%(7/13),对G2级患者的诊断敏感性分别为100%(12/12)和83.3%(10/12),对G3级患者的诊断敏感性分别为100%(3/3)和100%(3/3)。CT双期扫描和SRS对病灶直径≤2.0 cm的p NET诊断敏感性分别94.7%(18/19)和52.6%(10/19),差异有统计学意义(P=0.008);CT双期扫描和SRS对病灶直径>2.0 cm的p NET诊断敏感性分别为92.8%(13/14)和100%(14/14)。结论 CT双期扫描对p NET患者的诊断敏感性高于SRS。p NET患者的病理分级越低,CT双期扫描与SRS相比优势越明显。对于直径≤2.0 cm的病灶,SRS容易出现假阴性,需同时结合其他影像学检查。 展开更多
关键词 CT双期扫描 生长抑素受体显像 胰腺内分泌肿瘤
下载PDF
Evolution of microstructure and phase composition of Ti-3Al-5Mo-4.5V alloy with varied β phase stability 被引量:11
6
作者 Q.Xue Y.J.Ma +2 位作者 J.F.Lei R.Yang C.Wang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第12期2325-2330,共6页
The microstructure evolution and phase composition of an α+β titanium alloy, Ti-3Al-5Mo-4.5V(wt.%),have been investigated. Electron probe micro analysis(EPMA) quantitative results manifest that the stability of β p... The microstructure evolution and phase composition of an α+β titanium alloy, Ti-3Al-5Mo-4.5V(wt.%),have been investigated. Electron probe micro analysis(EPMA) quantitative results manifest that the stability of β phase decreases with increasing quenching temperature, which is influenced by the significant variation of β-stabilizing elements concentration. Detailed microstructure analysis shows that the β→ωphase transformation does occur when quenching at 750℃ and 800 ℃. The ω-reflections change from incommensurate ω-spots(750 ℃) to ideal ω-spots(800 ℃) as the β stability of the alloy decreases. Further the decrease of β phase stability encourages the formation of athermal α " martensite, which has the following orientation relationships: [111]β//[110]α",[100]p//[100]α " and [-110]p//[00-1]α" with respect to the β matrix. 展开更多
关键词 dual-phase titanium alloy β phase stability ω phase α" martensite MICROSTRUCTURE
原文传递
Effect of Microstructure on Hydrogen Induced Cracking Behavior of a High Deformability Pipeline Steel 被引量:13
7
作者 Xian-bo SHI Wei YAN +3 位作者 Wei WANG Lian-yu ZHAO Yi-yin SHAN Ke YANG 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2015年第10期937-942,共6页
The hydrogen induced cracking (HIC) behavior of a high deformability pipeline steel was investigated with three different dual-phase microstructures, ferrite and bainite (F+B), ferrite and martensite/austenite is... The hydrogen induced cracking (HIC) behavior of a high deformability pipeline steel was investigated with three different dual-phase microstructures, ferrite and bainite (F+B), ferrite and martensite/austenite islands (F+M/A) and ferrite and martensite (F+M), respectively. The HIC test was conducted in hydrogen sulfide (H2S)-saturated solution. The results showed that the steels with F+B and F+M/A dual-phase microstructures had both higher deformability and better HIC resistance, whereas the harder martensite phase in F+M microstructure was responsible for the worst HIC resistance. The band-like hard phase in dual-phase mi- crostructure was believed to lead to increasing susceptibility to HIC. 展开更多
关键词 pipeline steel high deformability dual-phase microstructure mechanical property hydrogen induced cracking
原文传递
Dual-Comb Ranging 被引量:14
8
作者 Zebin Zhu Guanhao Wu 《Engineering》 SCIE EI 2018年第6期772-778,共7页
Absolute distance measurement is a fundamental technique in mobile and large-scale dimensional metrology.Dual-comb ranging is emerging as a powerful tool that exploits phase resolution and frequency accuracy for high-... Absolute distance measurement is a fundamental technique in mobile and large-scale dimensional metrology.Dual-comb ranging is emerging as a powerful tool that exploits phase resolution and frequency accuracy for high-precision and fast-rate distance measurement.Using two coherent frequency combs,dual-comb ranging allows time and phase response to be measured rapidly.It breaks through the limitations related to the responsive bandwidth,ambiguity range,and dynamic measurement characteristics of conventional ranging tools.This review introduces dual-comb ranging and summarizes the key techniques for realizing this ranging tool.As optical frequency comb technology progresses,dualcomb ranging shows promise for various professional applications. 展开更多
关键词 RANGING dual-comb interferometer phase noise Timing JITTER Tight-locking Post-correction
下载PDF
Long-term stabilization of the optical fiber phase control using dual PID 被引量:11
9
作者 WU Yue CHEN Guozhu +1 位作者 SHEN Yong ZOU Hongxin 《Instrumentation》 2015年第4期40-46,共7页
We propose an approach of long-term stabilization of optical fiber phase by controlling a piezo-based phase modulator and a Peltier component attached to the fiber via a phase-locked loop( PLL) circuit w ith dual prop... We propose an approach of long-term stabilization of optical fiber phase by controlling a piezo-based phase modulator and a Peltier component attached to the fiber via a phase-locked loop( PLL) circuit w ith dual proportional-integral- derivative( PID) adjustment. With this approach,we can suppress the fast disturbance and slow drifting of optical fiber to satisfy the requirements of optical phase long-term locking. In theory,a mathematical model of an optical fiber phase control system is established. The disturbance term induced by environment influence is considered into the PLL model. The monotonous and continuous changing environment disturbance w ill cause a steady-state error in this theory model. The experimental results accords w ell w ith the theory. The steady-state performance,adjusting time,and overshoot can be improved by using the dual PID control. As a result,the long-term,highly stable and low noise fiber phase locking is realized experimentally. 展开更多
关键词 LONG-TERM STABILIZATION dual PID phase LOCKING fiber phase control.
下载PDF
Mechanical properties and deformation mechanisms of Ti-3Al-5Mo-4.5V alloy with varied β phase stability 被引量:10
10
作者 Q.Xue Y.J.Ma +2 位作者 J.F.Lei R.Yang C.Wang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第12期2507-2514,共8页
Evolution of deformation mechanisms and mechanical properties of Ti-3Al-5Mo-4.5V alloy with different β phase stability have been systematically investigated. β phase stability alteration is achieved through quenchi... Evolution of deformation mechanisms and mechanical properties of Ti-3Al-5Mo-4.5V alloy with different β phase stability have been systematically investigated. β phase stability alteration is achieved through quenching temperature variation from dual α+β field(700℃) to single β field(880℃). Tensile tests at ambient temperature show that apparent yield strength of the alloy experiences an abrupt decrease followed by a significant increase from 700℃ to 880℃. Work hardening behavior is characterized by transition from the initial two-regime feature to the three-stage outlook. Concurrently, the maximum working hardening rate drops from 14000 MPa to 3000 MPa, which is concurrent with the shrinking volume fraction of primary a phase. Detailed discussion about the relationship between deformation mechanisms and β phase stability has been outlined. 展开更多
关键词 dual-phase titanium alloy β phase stability Work hardening behavior Deformation mechanisms
原文传递
800MPa级DP钢冲压成形及裂纹扩展机理 被引量:12
11
作者 何昌炜 谢震 +2 位作者 章哲 王武荣 韦习成 《塑性工程学报》 CAS CSCD 北大核心 2013年第1期121-125,共5页
通过冲压弯曲试验研究800MPa级DP钢的极限拉伸,采用扫描电子显微镜观察分析钢板的微观组织及动态拉伸过程,探讨其微观组织与其稳机理的关系。结果表明,DP800钢断口为剪切型断裂。凸模圆角半径较小时,拉深弯曲断裂是由于折弯角过小而在... 通过冲压弯曲试验研究800MPa级DP钢的极限拉伸,采用扫描电子显微镜观察分析钢板的微观组织及动态拉伸过程,探讨其微观组织与其稳机理的关系。结果表明,DP800钢断口为剪切型断裂。凸模圆角半径较小时,拉深弯曲断裂是由于折弯角过小而在凸模圆角处折弯断裂;凸模圆角半径较大时,冲压弯曲断裂由于受到板料延伸率的限制,在材料流动受限的凹模圆角附近断裂。DP800的断口均分布着大量韧窝的韧性断裂,其裂纹扩展机理是微裂纹,主要产生于铁素体或马氏体/铁素体相界面,主裂纹沿两相界面或贯穿铁素体而继续扩展。 展开更多
关键词 双相钢 R t值 冲压成形 扩展机理
下载PDF
基于自适应遗传算法的双环信号配时优化模型 被引量:11
12
作者 王逸 姚志洪 +2 位作者 蒋阳升 赵斌 谭宇 《工业工程》 北大核心 2018年第5期72-80,共9页
为了有效利用交叉口时空资源,缓解城市交通拥堵,在双环相位方案的基础上,建立以交叉口平均延误为优化目标,以各相位绿灯时长为优化参数的双环信号配时优化模型,并采用自适应遗传算法对模型进行求解。选取4个十字交叉口,实地调查获得交... 为了有效利用交叉口时空资源,缓解城市交通拥堵,在双环相位方案的基础上,建立以交叉口平均延误为优化目标,以各相位绿灯时长为优化参数的双环信号配时优化模型,并采用自适应遗传算法对模型进行求解。选取4个十字交叉口,实地调查获得交叉口晚高峰流量数据,分别使用经典的Webster配时法和双环信号配时优化模型对交叉口信号配时方案进行优化。结果表明:与Webster配时法相比,双环信号配时优化模型优化结果更好,分别使4个交叉口平均延误减少11.36%、13.74%、3.72%和9.00%,能够有效改善交叉口运行状况;并且交叉口同相位内的两个流向的流量越不均衡,双环信号配时优化模型优化结果越好。 展开更多
关键词 交通工程 交通信号 双环相位 信号配时 遗传算法
下载PDF
Influence of silicon on the microstructures, mechanical properties and stretch-flangeability of dual phase steels 被引量:8
13
作者 Le-yu Zhou Dan Zhang Ya-zheng Liu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第8期755-765,共11页
Uniaxial tension tests and hole-expansion tests were carried out to determine the influence of silicon on the microstructures, mechanical properties, and stretch-flangeability of conventional dual-phase steels. Compar... Uniaxial tension tests and hole-expansion tests were carried out to determine the influence of silicon on the microstructures, mechanical properties, and stretch-flangeability of conventional dual-phase steels. Compared to 0.03wt% silicon, the addition of 1.08wt% silicon induced the formation of finer ferrite grains (6.8μm ) and a higher carbon content of martensite (Cm≈ 0.32wt%). AS the silicon level increased, the initial strain-hardening rate (n value) and the uniform elongation increased, whereas the yield strength, yield ratio, and stretch-flangeability decreased. The microstructures were observed after hole-expansion tests. The results showed that low carbon content martensite (Cm ≈ 0.19wt%) can easily deform in coordination with ferrite. The relationship between the mechanical properties and stretch-flangeability indicated that the steel with large post-uniform elongation has good stretch-flangeability due to a closer plastic incom- patibility of the ferrite and martensite phases, which can effectively delay the production and decohesion of microvoids. 展开更多
关键词 dual-phase steel silicon content mechanical properties MICROSTRUCTURE strain hardening
下载PDF
Effect of Heat Treatment on Microstructures and Mechanical Properties of Hot-Dip Galvanized DP Steels 被引量:8
14
作者 Enbao Pan Hongshuang Di +1 位作者 Guangwei Jiang Chengren Bao 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2014年第3期469-475,共7页
In order to simulate the hot-dipped galvanizing of dual-phase (DP) steel (wt%) 0.15C-0.1Si-1.7Mn, the DP steels were obtained by different annealing schedules. The effects of soaking temperature, time, and cooling... In order to simulate the hot-dipped galvanizing of dual-phase (DP) steel (wt%) 0.15C-0.1Si-1.7Mn, the DP steels were obtained by different annealing schedules. The effects of soaking temperature, time, and cooling rate on ferrite grain, volume fraction of martensite, and the fine structure of martensite were studied. Results showed that the yield strength (YS) of DP steel is sensitive to annealing schedule, while total elongation has no noticeable dependence on annealing schedule. Increasing soaking temperature from 790 to 850 ℃, the YS is the lowest at soaking temperature of 850 ℃. Changing CR1 from 6 to 24 ℃/s, the YS is the highest when CR1 is 12 ℃/s. Increasing soaking time from 30 to 100 s, the YS is the lowest at soaking time of 100 s. Besides, it was found that sufficient movable dislocations within ferrite grains and high martensite volume fraction can eliminate yield point elongation, decrease the YS, and increase ultimate tensile strength. Through TEM observations, it was also found that increasing annealing temperature promotes austenite transformation into twin martensite, and increases volume fraction of martensite at sufficient cooling rate. With increasing the martensite volume fraction, the deformation substructure in the ferrite is well developed. 展开更多
关键词 Advanced high strength steels (AHSS) dual-phase (DP) steel Microstructure Annealing temperature
原文传递
Enhanced Electromagnetic Interference Shielding in a Duplex-Phase Mg-9Li-3Al-1Zn Alloy Processed by Accumulative Roll Bonding 被引量:9
15
作者 Jiahao Wang Lin Xu +4 位作者 Ruizhi Wu Jing Feng Jinghuai Zhang Legan Hou Milin Zhang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2020年第4期490-499,共10页
High electromagnetic shielding performance was achieved in the Mg-9Li-3Al-1Zn alloy processed by accumulative roll bonding(ARB).The microstructure,electromagnetic interference shielding effectiveness(SE) in the freque... High electromagnetic shielding performance was achieved in the Mg-9Li-3Al-1Zn alloy processed by accumulative roll bonding(ARB).The microstructure,electromagnetic interference shielding effectiveness(SE) in the frequency of 30-1500 MHz and mechanical properties of the alloy were investigated.A model based on the shielding of the electromagnetic plane wave was used to theoretically discuss the EMI shielding mechanisms of ARB-processed alloy.Results indicate that the SE of the material increases gradually with the increase in the ARB pass.The enhanced SE can be attributed to the obvious microstructure orientation caused by ARB,and the alternative arrangement of alpha(Mg) phase and beta(Li)phase.In addition,with the increase in ARB pass,the number of interfaces between layers increases and the grain orientation of each layer tends to alignment along c-axis,which is beneficial to the reflection loss and multiple reflection loss of the incident electromagnetic wave. 展开更多
关键词 ACCUMULATIVE roll bonding(ARB) MG-LI ALLOY dual-phase alloys Electromagnetic interference Reflection loss
原文传递
超声波测距的双相位检测方法 被引量:8
16
作者 袁梅 汪鹏程 张学军 《电子测量技术》 北大核心 2021年第17期112-117,共6页
超声波测距是最常见的测距技术手段,性价比极高。但常用超声波回波测距中信号整形经常会引起的测距误差,其主要原因是由于起振周期丢失及反射信号幅度差异使测量的信号飞行时间越过了接收信号起始时间点所引起的。所提出的双相位检测方... 超声波测距是最常见的测距技术手段,性价比极高。但常用超声波回波测距中信号整形经常会引起的测距误差,其主要原因是由于起振周期丢失及反射信号幅度差异使测量的信号飞行时间越过了接收信号起始时间点所引起的。所提出的双相位检测方法,通过发射一组64周期载波,2周期调制信号的临界调制信号,同时开始计时,当接收信号幅值超过特定阈值时停止计时,进而检测阈值点信号的相位,得到接收信号的起始时间点,再使用载波相位校正法来消除信号整形带来的误差后得出距离测量结果。经过仿真测试和实验测试,结果表明实际测量精度几乎不受噪声和反射信号幅度的影响,在50~200 mm的测距范围,双相位测距装置测距实验标准差不超过1 mm,测距精准度得到有效提高。 展开更多
关键词 超声波测距 双相位 调制信号 抽取包络 相位校正
下载PDF
Microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels 被引量:7
17
作者 Zhi-gang Wang A i-min Zhao +3 位作者 Zheng-zhi Zhao Jie-yun Ye Di Tang Guo-sen Zhu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2012年第10期915-922,共8页
The microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tens... The microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile test. The results show that Si can promote the transformation of austenite (γ) to ferrite (α), enlarge the (α+γ) region, and increase the aging stability of martensite by inhibiting carbide precipitation. Adding Cr leads to the formation of retained austenite and martensite/austenite (M/A) constituents, as well as the decomposi- tion of martensite during the overaging stage. Both of the steels show higher initial strain-hardening rates and two-stage strain-hardening characteristics. The C-Mn-Si-Nb steel shows the higher strain-hardening rate than the C-Mn-Cr-Nb steel in the first stage; however, there is no significant difference in the second stage. Although the tensile strength and elongation of the two steels both exceed 1000 MPa and 15%, respectively, the comprehensive mechanical properties of the C-Mn-Si-Nb steel are superior. 展开更多
关键词 high strength steel dual-phase steel alloying elements microstructure mechanical properties sWain hardening
下载PDF
Effect of cooling temperature on the microstructure and corrosion behavior of X80 pipeline steel 被引量:7
18
作者 Jing Ma Fan Feng +2 位作者 Bai-qing Yu Hai-feng Chen Li-feng Fan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2020年第3期347-353,共7页
Dual-phase accelerated cooling(DPAC) was applied to X80 pipeline steel to obtain its microstructure with different amounts of bainite and ferrite. The microstructure, hardness, and polarization behaviors of the steel,... Dual-phase accelerated cooling(DPAC) was applied to X80 pipeline steel to obtain its microstructure with different amounts of bainite and ferrite. The microstructure, hardness, and polarization behaviors of the steel, cooled to different temperatures, were investigated. Results showed that, with decreasing cooling temperature, the amount of polygon ferrite(PF) increased while that of acicular ferrite(AF) decreased. The amount of bainite correspondingly decreased, except when cooled to 760°C. Moreover, the grain size of ferrite increased. The corrosion behaviors of different phases were distinct. Martensite/austenite(M/A) islands presented at the grain boundary of the PF phase caused small pits. Numerous micro-corrosion cells were formed in the AF and bainite phases, where micropores were prone to form. X80 pipeline steel cooled to 700°C had the best corrosion resistance in the simulated seawater. The decreased amount of the PF phase reduced the area of cathode, resulting in slight corrosion. About 40 vol% of the bainite phase provided strength while the PF phase provided adequate ductility to the X80 steel. It was concluded that the appropriate cooling temperature was 700°C for ideal corrosion resistance and mechanical properties. 展开更多
关键词 X80 pipeline steel dual-phase accelerated cooling MICROSTRUCTURE corrosion behavior
下载PDF
Numerical simulation on the microstress and microstrain of low Si-Mn-Nb dual-phase steel 被引量:7
19
作者 Hai-feng Dong Jing Li +2 位作者 Yue Zhang Joongkeun Park Qing-xiang Yang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2010年第2期173-178,共6页
According to the stress-strain curves of single-phase martensite and single-phase ferrite steels,whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel,the stress-strain cur... According to the stress-strain curves of single-phase martensite and single-phase ferrite steels,whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel,the stress-strain curve of the low Si-Mn-Nb dual-phase steel was simulated using the finite element method(FEM).The simulated result was compared with the measured one and they fit closely with each other, which proves that the FE model is correct.Based on the FE model,the microstress and microstrain of the dual-phase steel were analyzed. Meanwhile,the effective factors such as the volume fraction of martensite and the yield stress ratio between martensite and ferrite phases on the stress-strain curves of the dual-phase steel were simulated,too.The simulated results indicate that for the low Si-Mn-Nb dual-phase steel, the maximum stress occurs in the martensite region,while the maximum strain occurs in the ferrite one.The effect of the volume fraction of martensite(fm) and the yield stress ratio on the stress-strain curve of the dual-phase steel is small in the elastic part,while it is obvious in the plastic part.In the plastic part of this curve,the strain decreases with the increase of f_M,while it decreases with the decrease of the yield stress ratio. 展开更多
关键词 dual-phase steel microstress MICROSTRAIN numerical simulation finite element method(FEM)
下载PDF
Mechanical properties and fracture mechanism of as-cast MnFeCoCuNix high-entropy alloys 被引量:8
20
作者 Cheng-yan ZHU Hao WU +3 位作者 He-guo ZHU Xiang-dong LI Chun-lei TU Zong-han XIE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第1期222-231,共10页
MnFeCoCuNix high-entropy alloys(HEAs)with different Ni contents were fabricated by vacuum induction melting.XRD and SEM−EDS were used to analyze the phase constitution and structure,and the tensile properties of the s... MnFeCoCuNix high-entropy alloys(HEAs)with different Ni contents were fabricated by vacuum induction melting.XRD and SEM−EDS were used to analyze the phase constitution and structure,and the tensile properties of the samples were determined using a universal tensile tester.The results show that the HEAs consist of a dual-phase structure,in which FCC1 phase is rich in Fe and Co,while the FCC2 phase has high contents of Cu and Mn.As Ni content increases,the segregation of Cu decreases,accompanied by the decrease of FCC2 phase.Moreover,the tensile strength of the HEAs increases first and then decreases,and the elongation increases slightly.This is attributed to the combined effect of interface strengthening and solid solution strengthening.The in-situ stretched MnFeCoCuNi0.5 alloy shows obvious neck shrinkage during the tensile fracture process.In the initial deformation stage,the slip lines show different morphologies in the dual-phase structure.However,in the later stage,the surface slip lines become longer and denser due to the redistribution of atoms and the re-separation of the dissolved phase. 展开更多
关键词 high-entropy alloys dual-phase structure mechanical properties in-situ stretching fracture mechanism
下载PDF
上一页 1 2 137 下一页 到第
使用帮助 返回顶部