H.B. Wu
,
H.T. Jiang
,
S.W. Yang
,
D. Tang
,
X.L. He
,
null
金属学报(英文版)
Cooled in water after isothermal relaxation of deformed austenite for different times, an Nb-bearing microalloyed steel always exhibits synthetic microstructures, in which bainitic ferrite dominates. Dislocation configurations and distributions of strain induced precipitates inside bainitic ferrite of samples relaxed for different times were distinct. When compared with the austenite model steel, which maintained fcc structure even at room temperature, the strain induced precipitates were not found in the sample without relaxation whereas these were distributed outside dislocations in sample relaxed for 1000s. Most of the strain induced precipitates distribute along dislocations and pin dislocations in sample relaxed for appropriate time. After bainitic transformation, the dislocations formed in deformed austenite remain to be pinned by the precipitates. When these samples were reheated to and held at 650 or 700¡æ, the non-equilibrious microstructures tended to evolve into equilibrious ones. The sample relaxed for 60s displayed the highest thermo-stability, whereas microstructure evolution was the quickest in the sample relaxed for 1000s even though it was the softest prior to reheating. Dislocations inside laths got rid of pinning of precipitates, and their polygonization became the precursor to the evolution of microstructures during reheated and held, followed by gradual disappearance of lath boundaries caused by dislocation climbing. Finally, recrystallization occurred and polygonal ferrite appeared. By hardness measurement, it was found that softening is not a single process occurring during reheated, in which hardness fluctuates with time. There were two peaks in the hardness-time curve of each sample having undergone relaxation, while single peak occured in the curve of the sample not being relaxed. These results indicated that the thermo-stability of microstructures was determined by their history of formation to a considerable degree.
关键词:
bainite
,
null
,
null
,
null
S.T. Wang
,
S.W. Yang
,
K.W. Gao
,
X.L. He
金属学报(英文版)
For 18 months, a newly developed low alloy weathering steel has been exposed in two coastal sites (Qingdao in the north China, Wanning in the south China). The different corrosion behaviors of the exposed side and the underside of the samples were characterized by X-ray diffraction (XRD), polarization curve, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and N$_{2}$ adsorption approach. It was found that the samples exhibited higher corrosion rate in Wanning than that in Qingdao. The underside of the samples corrodes more seriously than the exposed side in Qingdao, whereas the result in Wanning is just the reverse. The protection performance of rust layers mainly depends on its compactness and the enrichment of Cu and Cr is a secondary causation. The different compactness of rust layers in the exposed side and the underside originates from different corrosion conditions of the two sides.
关键词:
alloy weathering steel
,
null
Transactions of Nonferrous Metals Society of China
The method for preparing a new solid lubrication system of nano S-W-S was presented. The microstructure of the S-W-S nano cluster was investigated using TEM and XRD. The system is a mixture clusters of both monocrystal and polycrystal of layered hexagonal structure with one tungsten atom linking with two sulphur atoms, and the week Van der Waals' force bonding together the different layers. The changes of electronic structure were studied with XPS. The hybridization of different electronic shelf orbitals of the sulphur atom in the nano cluster is regarded as the quantum size effect. The clusters are found to be of a closed spherical,structure without any dangling bond.
关键词:
solid lubrication system;nanometer cluster;quantum size effect;powders
鲁二敬
,
卢峰华
,
许鸿吉
,
谢明
,
钮旭晶
机械工程材料
通过周期浸润腐蚀试验，对比研究了S355．12W耐候钢和Q345R低合金钢在NariSOs溶液中的耐腐蚀性能，并用扫描电镜对腐蚀产物进行了观察和分析。结果表明：在相同试验条件下，S355J2W耐候钢的腐蚀速率低于Q345R钢的；S355J2W耐候钢会在表面形成黑褐色锈层，而Q345R钢表面形成橘红色易剥落的疏松锈层；S355J2W耐候钢腐蚀产物微观形貌为沿放射性方向生长的针状晶体，Q345R钢为颗粒状聚合物堆积而成，形状无规则，颗粒之间有较大的空隙。
关键词:
S355J2W耐候钢
,
周期浸润腐蚀试验
,
耐腐蚀性能
WU Shaobin
,
R. J. Arsenault
,
I. R. Kramer Metallurgical Materials Laboratory
,
University of Maryland
,
USA.
材料科学技术（英文）
Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual "W"-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).
关键词:
α-brass
,
null
,
null
,
null
谷晓鹏
,
段珍珍
,
邓钢
,
谷晓燕
材料工程
doi:10.11868/j.issn.1001-4381.2015.02.004
利用激光-MAG复合焊和MAG焊进行了厚板S355J2W+N低碳钢的焊接实验,分析了两种焊接方法接头的微观组织和力学性能.结果表明:复合焊和MAG焊焊缝接头均由焊缝区、过热区、重结晶区和不完全重结晶区构成,复合焊接头截面呈“高脚杯”状特点,焊缝填充量和热影响区宽度较MAG焊明显减小.复合焊由于冷却速率快,过热区魏氏组织略有增多,硬度高于MAG焊,抗拉强度和弯曲性能与MAG焊相比,无显著差异,均能够满足生产标准的要求.
关键词:
S355J2W+N
,
激光
,
MAG
,
复合焊
,
接头组织
,
性能
李道华
,
叶向荣
,
周益明
,
忻新泉
材料保护
doi:10.3969/j.issn.1001-1560.1999.04.002
在锌表面获得了多种不同颜色且具有金属光泽的不溶性Mo(W)-S-Zn簇合物转化膜.所获膜层具有良好的耐蚀性能和装饰效果,加热处理后颜色将发生变化,加速腐蚀试验结果表明,金黄色膜耐蚀性最佳.FT-IR、FT-Raman、XPS和AES分析表明,该膜层厚度约为60 nm.钼在膜表面的价态为+6价,而在膜内则以+6、+4价共存.从AES深度分布曲线可知,其组织为32.5%Zn,19.3%Mo,39.4%S,8.5%O.膜为多分子层组成的复杂体系,其颜色是各组分统计分布的结果.
关键词:
Mo(W)-S-Zn簇合物
,
转化膜
,
XPS
,
AES
董斌
,
祖继锋
,
高亚臣
,
宋瑛林
,
雷明凯
材料研究学报
doi:10.3321/j.issn:1005-3093.2004.06.018
用Z扫描方法测量了金属团簇化合物W2Ag4S8(dppf)2的非线性光学响应,发现团簇W2Ag4S8(dppf)2具有显著的反饱和吸收和自聚焦等非线性光学性质.应用激发态理论分析了团簇W2Ag4S8(dppf)2的非线性吸收和非线性折射,结果与实验数据一致.通过数值模拟获得激发态和基态吸收截面比值Ka及非线性折射度比值Kr,阐述了Ka和Kr的物理意义.确定了团簇W2Ag4S8(dppf)2的三阶极化率x(3).团簇化合物W2Ag4S8(dppf)2对脉宽为纳秒的激发脉冲限幅效果比较好.
关键词:
无机非金属材料
,
金属团簇化合物
,
Z扫描
,
非线性光学
,
激发态吸收
,
激发态折射
