YU Wei
,
QIAN Ya-jun
,
WU Hui-bin
,
YANG Yue-hui
钢铁研究学报(英文版)
Two types of steel, C-Mn-Cr-Mo-B microalloyed steel and C-Mn-Mo-Nb-Cu-B microalloyed steel, are designed to develop 1000 MPa ultra-high strength steel. Two kinds of processes, thermomechanical controlled process (TMCP) combined with traditional off-line quenching and tempering (QT) process versus controlled rolling process (CR) combined with direct quenching and tempering (DQ+T) process, are applied. The effect of heat treatment processing mode on the microstructure and mechanical properties is studied. The relationship between microstructure and mechanical properties is investigated by SEM and TEM. After tempering at 450 to 550 ℃ for 1 h, the steel produced by TMCP+QT process shows combination of excellent strength and low temperature toughness. The yield strength is above 1000 MPa, elongation above 15% and impact energy at -40 ℃ more than 30 J. After tempering at 450 ℃, a large number of ε-Cu particles precipitated in C-Mn-Mo-Nb-Cu-B steel produced by CR+DQ+T process lead to a significant increase in yield strength. And after tempering at 500 to 600 ℃, the yield strength of the steel is further improved to 1030 MPa because of precipitates, such as nitride or carbide of niobium, carbide of molybedenum and vanadium. When the tempering temperature is increased above 620 ℃, the yield strength is still higher than 1000 MPa and elongation is above 20% and impact energy at -40 ℃ is more than 35 J. After tempering at above 500 ℃, the toughness of the steel treated by TMCP+QT process is superior to that of steel by CR+DQ+T process.
关键词:
Heat treatment, High strength steel, Microtructures, Mechanical properties
CHEN Zhiming
,
LUO Fei
,
XU Yuge
,
YU Wei
钢铁研究学报(英文版)
Roll eccentricity is an important factor causing thickness variations during hot strip rolling and might define the limit of strip thickness control accuracy. An improved multiresolution wavelet transform algorithm was proposed to compensate for the roll eccentricity. The wavelet transform method had good localization characteristics in both the time and frequency domains for signal analysis; however, the wavelet method had a frequencyaliasing problem owing to the less than ideal cutoff frequency characteristics of wavelets. This made its component reconstruction of an inaccurate signal. To eliminate inherent frequency aliases in the wavelet transform, fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) were combined with the Mallat algorithm. This synthesis was described in detail. Then, the roll eccentricity component was extracted from rolling force signal. An automatic gauge control (AGC) system added with a multiresolution wavelet analyzer was designed. Experimental results showed that the antialiasing method could greatly restrain the inverse effect of eccentricity and the thickness control accuracy was improved from ±40 μm to ±15 μm.
关键词:
hot strip rolling;roll eccentricity compensation;wavelet analysis;frequency alias
X.B. Tian
,
X.F. Wang
,
A.G. Liu
,
L.P. Wang
,
S. Y. Wang
,
B. Y. Tang and P. K. Chu 1)Advanced Welding Production & Technology National Key Laboratory
,
Harbin Institute of Technology
,
Harbin 150001
,
China 2)Department of Physics & Materials Science
,
City University of Hong Kong
,
China
金属学报(英文版)
The research on plasma immersion ion implantation has been conducted for a little over ten years. Much is needed to investigate including processing technlogy, plasma sheath dynamics, interaction of plasma and surface, etc. Of the processing methods elavated temperature technique is usually used in PIII to produce a thick modified layer by means of the thermal diffusion. Meanwhile plasma ion heating is more recently developed by Ronghua Wei et al[1]. Therefore the temeperature is a critical parameter in plasma ion processing. In this paper we present the theoretical model and analysize the effect of imlantation voltage, plasma density, ion mass,etc on the temperature rise.
关键词:
plasma immersion ion implantation
,
null
,
null
夏小建
量子电子学报
doi:10.3969/j.issn.1007-5461.2009.06.010
采用Wei-Norman方法,求出含时变电压源的介观LC电路随时间演化的精确解,应用相空间准概率分布函数,研究了时变电源作用下介观LC电路相干态的量子特性,结果表明此函数是一个二维运动的Gauss波包,其中心电量和磁通呈余弦和正弦变化.
关键词:
量子光学
,
LC回路
,
介观电路
,
相干态
,
量子态演化
,
相空间的准概率分布函数
中国腐蚀与防护学报
N。1Atmospheric Corrosivlty for Steels………………………………………………… .LIANG Caideng HO[I i。-tat（6）Caustic Stress Corrosion Cr。king of Alloy 800 Part 2.The Effect of Thiosul执e……………………………………… KONG De-sheng YANG Wu ZHAO Guo-zheng HUANG De.ltL。ZHANG Yu。。he CHEN She。g-bac（13）SERS slid E16CttOCh6iniC81 Stlldy Of Illhibit1Oli M6ch＆tllsth Of ThlollY68 Oil ITOll ID H....
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