Y. Wu
,
C.S. He
,
X. Zhao
,
null
,
null
金属学报(英文版)
Effects of magnetic field strength on the evolution of recrystallization microstructure and recrystallization texture in cold-rolled interstitial-free steel were investigated after annealing at 660°C in a magnetic field up to 12T. Magnetic annealing was found to retard the recrystallization and induce the recrystallized grains elongated along the magnetic field direction. An interesting phenomenon is that the magnetic field shows the strongest effect at 1T.
关键词:
Magnetic annealing
,
annealing
,
Recrystallization
,
Tex
Wei Guo Weimin Mao
材料科学技术（英文）
With the help of electron back scattering diffraction techniques and field emission microscope, the misorientation and the precipitation environment of Goss grains in conventional grain-oriented steel were observed and investigated at the initial stage of secondary recrystallization. It reveals that the abnormal Goss grains have a high fraction of high angle boundaries ranging from 25 to 40 deg. The most important observation is that some of {110}<001> grains in matrix indicated higher particle density than their neighbor grains during final annealing at 875°C before secondary recrystallization, which could create a favorable environment for their abnormal grain growth. Based on misorientation and precipitation results, the abnormal growth mechanism of Goss grains was sketched.
关键词:
Recrystallization
,
析出物
,
高斯晶粒
,
反常晶粒长大
,
取向电工钢
Guoliang Hu
材料科学技术（英文）
Electropulsing-induced recrystallization and its effect on mechanical properties of oriented silicon steel strips (Fe-3.0%Si) were studied by optical microscopy, scanning electron microscopy and electron back-scatter diffraction. The results indicated that electropulsing accelerated recrystallization, and decreased the temperature of recrystallization. Electropulsing favors refinement of the grain structure of the alloy. Effects of electropulsing on strength and elongation of the alloy were discussed from the point view of dislocation dynamics, microstructural changes, and electropulsing kinetics.
关键词:
Recrystallization
A.Di Schino
,
G.Abbruzzese
,
J.M.Kenny
材料科学技术（英文）
A mathematical model, able to describe the recrystallization and grain growth in metals, has been developed. Taking into account the classical constitutive equations of the Taylor’s theory, the model involves only two free parameters (the dislocation density and the initial number of nuclei). Results from the model are here discussed in comparison with measurements performed on an AISI 304 stainless steel. The predictions of the model are in good agreement with experimental results. As cross check of the model prediction, the independent parameter “dislocation density” was found to properly correlate to the mechanical properties of the steel and to X-ray diffraction measurements, according to Taylor’s and Debye’s relations respectively.
关键词:
Recrystallization
,
null
,
null
Jing HAN
,
Hongtao CHEN
,
Mingyu LI
金属学报(英文版)
A small Pb-free solder joint exhibits an extremely strong anisotropy due to the body-centered tetragonal (BCT) lattice structure of β-Sn. Grain orientations can significantly influence the failure mode of Pb-free solder joints under thermomechanical fatigue (TMF) due to the coefficient of thermal expansion (CTE) mismatch of β-Sn grains. The research work in this paper focused on the microstructure and damage evolution of Sn3.0Ag0.5Cu BGA packages as well as individual Sn3.5Ag solder joints without constraints introduced by the package structure under TMF tests. The microstructure and damage evolution in cross-sections of solder joints under thermomechanical shock tests were characterized using optical microscopy with cross-polarized light and scanning electron microscopy (SEM), and orientations of Sn grains were determined by orientation imaging microscopy (OIM). During TMF, obvious recrystallization regions were observed with different thermomechanical responses depending on Sn grain orientations. It indicates that substantial stresses can build up at grain boundaries, leading to significant grain boundary sliding. The results show that recrystallized grains prefer to nucleate along pre-existing high-angle grain boundaries and fatigue cracks tend to propagate intergranularly in recrystallized regions, leading to an accelerated damage after recrystallization.
关键词:
Pb-free solder
,
null
,
null
,
null
,
null
L.J. Zhu
金属学报(英文版)
Because Si is a noncarbide forming element, a multiphase microstructure consisting of ferrite, bainite, and retained austenite, at room temperature, can be formed by controlling the thermomechanical process strictly. The cooling schedules must be restricted by the formation of pearlite and cementite. In the present article, a new integrated mathematical model for prediction of microstructure evolution during controlled rolling and controlled cooling is developed for a typical kind of low carbon Si-Mn TRIP steel, which consists of temperature simulation, recrystallization, and transformation models. The influence of Si contents has been thoroughly investigated. The calculated results indicate that Si retards recrystallization, restrains austenite grain growth as well as accelerates polygonal ferrite transformation.
关键词:
TRIP steel
,
null
,
null
,
null
,
null
Fei DING
,
Guoyi TANG
,
Zhuohui XU
,
Shaoquan TIAN
,
null
,
null
,
null
材料科学技术（英文）
Specially designed wire-drawing equipment with multiple electropulse generator was introduced. The influences of multiple electropulses processing on the microstructure and properties of the hardened steel wire were investigated. Samples treated by direct current under the same current density as that in multiple electropulses processing were carried out for contrast analysis. The results show that the optimized parameters of multiple electropulses processing will be facilitated to increase the nucleation rate and slow down the growth rate of recrystallized grains. Consequently, massive superfine grains of micro and sub-micro scale could be found in the steel wire. Thereby, the elongation was significantly enhanced with a relatively small strength reduction in comparison with as-received cold-drawing steel wires. Outstanding mechanical properties of steel wire were obtained.
关键词:
Multiple electropulses
,
null
,
null
,
null
,
null
孙震
,
张备
上海金属
通过金相观察的方法,研究了K60、X70管线钢在不同加热温度下奥氏体晶粒长大的规律及在不同变形量和变形温度下奥氏体晶粒再结晶的规律.结果表明:加热温度分别达到1 150℃和1 200℃时,K60、X70晶粒尺寸急剧增大;随着变形温度的提高,K60、X70奥氏体再结晶的临界变形量均降低;变形温度在1 150℃,变形量分别为50％和30％时,K60、X70再结晶程度可达90％以上.相比K60,X70未再结晶区狭小,为避免混晶的产生,轧制过程应尽量避开部分再结晶区.
关键词:
管线钢
,
再结晶
,
奥氏体晶粒
,
控制轧制
