Quancheng ZHANG
,
Jiansheng WU
,
Wenlong ZHENG
,
Jianjun WANG
,
Jiaguang CHEN
,
Xiaofang YANG
,
Aibai LI
材料科学技术（英文）
The iron rust phases formed on low alloy steels containing different quantities of Cr element have been characterized using EPMA, Raman spectroscopy, TEM, optical microscopy etc. The ion selective properties of synthesized rust films with the same phase constituent as the atmospheric corrosion products were investigated using self-made apparatus. The results showed that corrosion loss of steels exposed in marine atmosphere decreased rapidly as the Cr content of the steel was increased. Cr-containing steels were covered by a uniform compacted rust layer composed of fine particles with an average diameter of several nanometers. Inner rust layer of Cr-containing steel (2 mass fraction) was composed of a-CrxFe1-xOOH, with Cr content of about 5 mass fraction. Such rust layer showed cation selective property, and could depress the penetration of Cl- to contact substrate steel directly.
关键词:
Corrosion
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null
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null
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null
Xianping DONG
,
Jiansheng WU
材料科学技术（英文）
Crystallization behavior of amorphous Cr-Si-Ni thin films was investigated by means of high temperature in situ X-ray diffraction measurements. The diffraction spectra were recorded isothermally at temperature between 250 and 750 degreesC. The in situ testing of crystallization enables the direct observation of structure evolution which is dependent on heat treatment. Based on the testing results, the grain sizes of the crystalline phases were compared and phase transition tendency was understood. In the mean time, electrical properties of the films as functions of annealing temperature and time have been studied. The increase of volume fraction of CrSi2 crystalline phases in the Cr-Si-Ni films leads to the decrease in conductivity of the films. The annealing behavior of temperature coefficient of resistance (TCR) is a result of competition between a negative contribution caused by the weak localization effects in amorphous region and a positive contribution caused by CrSi2 grains. Thus the proper mixture of amorphous and crystalline constituents could result in a final zero TCR.
关键词:
Bin ZHAO
,
Jiansheng WU
,
Zhonghou LI
,
Xiaoping LIU
,
Zhong XU
材料科学技术（英文）
Due to the slow cooling rate in the alloying furnace, large amount of brittle precipitates appear in the alloyed layers which are formed by the DGPSA (Double Glow Plasma Surface Alloying) with tungsten-molybdenum. It causes the mechanical properties of the samples to be seriously degraded. Qualitative phase analysis reveals that they are mainly composed of the p-phase, and a small amount of carbide, M6C. In this paper the microstructure and thermodynamic factors of the precipitates are exhaustively investigated. There are two transformation noses in the isothermal transformation (IT) diagram of the precipitates. As a major object of this work, an effective measure is offered to depress the deposition of the precipitates.
关键词:
Shengquan CAO
,
Jinxu ZHANG
,
Jiansheng WU
,
Jiaguang CHEN
材料科学技术（英文）
In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in the st14 steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone. During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110> orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.
关键词:
Electron backscattered diffraction (EBSD)
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null
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null
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null
Qingchao TIAN
,
Jiansheng WU
,
Yifeng CHENG
材料科学技术（英文）
Ti50.6Pd30Ni19.4 and Ti51Pd28Ni21(Ce) alloys have been prepared under various temperatures for long time annealing. Differential scanning calorimetery (DSC), X-ray diffraction (XRD) and tensile test were employed to investigate the phase transformation behavior and superelasticity of the alloys. It has been found that the phase transformation temperature of Ti50.6Pd30Ni19.4 is about 40℃ higher than that of Ti51Pd28Ni21(Ce), and do not change much with different annealed temperature. Obvious superelasticity is retained in Ti50.6Pd30Ni19.4 alloy annealed at 400℃ for 18 h, and annealing at higher temperature shows a deterioration of this property. The Ce addition in Ti51Pd28Ni21(Ce) alloy significantly delays recrystallization, increases yied strength and elastic modulus, but the superelasticity is poor.
关键词:
TiNi-Pd
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null
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null
Guangmin LUO
,
Jiansheng WU
,
Qingsen MENG
材料科学技术（英文）
T91 steel is one of the new materials presently employed in power plant pipe components. The creep rupture strength and microstructure of the T91+10CrMo910 and T91+13CrMo44 welded joints were analyzed during creep rupture tests. Creep transgranular ductile rupture occurred at the 10CrMo910 matrix in the T91+10CrMo910 welded joints and creep intergranular brittle rupture occurred at the 13CrMo44 HAZ in the T91+13CrMo44 joints. Microhardness measurements showed high hardness at the heat affected zone (HAZ) of T91 and a sharply drop at the 13CrMo44 HAZ during creep rupture. The metallographic tests showed that no obvious microstructure degradation was observed in the 10CrMo910 HAZ and matrix, while creep cracks appeared at the 13CrMo44 HAZ. T91 steel had relatively high creep resistant strength in the welded joints tested. Recovery occurred in the T91 HAZ with the growth of subgrain size and the decrease of dislocation density during creep. It was concluded that the dissimilar joints of T91 and low alloy heat-resistant steel should have close creep strength matching to increase the service life of the overall joints at elevated temperature.
关键词:
T91 steel
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null
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null
Yuping ZHANG
,
Jinxu ZHANG
,
Jiansheng WU
材料科学技术（英文）
parameters such as L*, a* and b* are selected to describe the surface color of alloys while the color difference (ΔE*) is used to evaluate the color stability. The results show that with the increase of Sn, the color change of Cu-Mn-Zn alloys is greatly reduced and the corrosion resistance in the synthetic sweat is improved dramatically. However, up to 4.4wt pct Sn does not change the color of Cu-Mn-Zn alloys much. XPS and AES are employed to analyze the tarnished surface. It is proved that a Sn enriched film is formed and Sn takes the form of Sn oxide. This thin and protective oxide film can prevent alloy from further tarnishing
关键词:
Sn
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null
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null
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null
