Yuanyuan Song Xiuyan Liy Lijian Rong Yiyi Li
材料科学技术（英文）
The thermal stability of the reversed austenite in a low carbon Fe-13%Cr-4%Ni-Mo (in wt pct) martensitic stainless steel was investigated by X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer. Different amount of the reversed austenite was obtained by controlling tempered temperature. It was found that the amount of the reversed austenite increased after keeping the specimens at liquid nitrogen temperature for 72 h. The mechanism of the anomalous phase transformation from martensite to austenite was discussed.
关键词:
Low temperature
,
Martensite
,
Austenite
,
Phase transformation
,
Magnetization vs. temperature
Yuanyuan Song Xiuyan Liy Lijian Rong Yiyi Li
材料科学技术（英文）
The thermal stability of the reversed austenite in a low carbon Fe-13%Cr-4%Ni-Mo (in wt pct) martensitic stainless steel was investigated by X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer. Different amount of the reversed austenite was obtained by controlling tempered temperature. It was found that the amount of the reversed austenite increased after keeping the specimens at liquid nitrogen temperature for 72 h. The mechanism of the anomalous phase transformation from martensite to austenite was discussed.
关键词:
Low temperature
,
Martensite
,
Austenite
,
Phase transformation
,
Magnetization vs. temperature
W.D. Wang
材料科学技术（英文）
Solid state phase transformation characteristics of the body centred β(Ti) into the hexagonal closed packed α(Ti) in Ti45Al8Nb-(0, 0.3, 0.5 and 0.8 at. pct) B alloys were investigated by heat treatment to clarify γ/α2 lamellar microstructure refinement induced by B addition. Experimental results confirmed two kinds of boron-reduced grain refinement mechanisms through refining either β phase thenα phase (β-refinement) or α phase directly (α-refinement) to refine lamellar microstructure at room temperature; however, the role of α-refinement dominated the as-cast lamellar microstructure refinement over β-refinement in Ti45Al8NbxB alloy. It was also found that during the α-refinement the convoluted flake- and plate-like borides along β grain boundaries assisted nucleation of α phase, and the particle-like borides near β grain boundaries impeded α phase growth.
关键词:
Titanium aluminides
,
Phase transformation
,
Microstructure
Zhenni ZHOU
金属学报(英文版)
The pearlite transformation in a Mo-containing iron alloy was investigated under 12~T magnetic field. The pearlite transformation was accelerated owing to the application of a strong magnetic field. Pearlite was of degenerated morphology without the presence of a strong magnetic field; but the degeneracy of pearlite is reduced when a strong magnetic field was applied, which may be attributed to the effect of strong magnetic field on faster carbon diffusion and less molybdenum segregation caused by a strong magnetic field.
关键词:
Steels
,
Pearlite
,
Phase transformation
,
Strong magnetic field
Esmaeil Jafari
材料科学技术（英文）
The influence of deformation temperature, strain rate and alloying elements such as chromium, nickel, copper, on corrosion resistance of a 304 stainless steel after plastic deformation was investigated. The techniques employed were tensile test at room and elevated temperature, deep drawing tests at various strain rates, X-ray diffraction test and potentiodynamic and cyclic polarization, metallography by optical and scanning electron microscopy. Results showed that chromium, nickel and copper had a significant effect on corrosion resistance of steel after plastic deformation. It was observed that corrosion resistance after plastic deformation was a function of deformation temperature and alloying elements.
关键词:
Corrosion resistance
,
Plastic Deformation
,
Stainless Steel
,
Phase Transformation
,
Polarization Test
Xiaoqiang Hu Namin Xiao Xinghong Luo Dianzhong Li
材料科学技术（英文）
Thermodynamic calculation, thermal analysis, and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program, differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer, respectively. Several critical phase transformation points were determined by combining experimental results with calculations. Two individually stable phases of Nb(C, N) and VN, instead of one single phase MX (X: C, N), M23C6 or Laves phases, were predicted in the calculated equilibrium phase diagram. An unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered steel. Two kinds of spherical Nb(C, N) with different size were recognized as the primary and the secondary precipitates of Nb(C, N) which contain different V contents. It was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb(C, N).
关键词:
Heat resistant steel
,
9-12%Cr steel
,
phase transformation
,
microstructure
,
MX precipitate
Xiaoqiang Hu Namin Xiao Xinghong Luo Dianzhong Li
材料科学技术（英文）
Thermodynamic calculation, thermal analysis, and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program, differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer, respectively. Several critical phase transformation points were determined by combining experimental results with calculations. Two individually stable phases of Nb(C, N) and VN, instead of one single phase MX (X: C, N), M23C6 or Laves phases, were predicted in the calculated equilibrium phase diagram. An unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered steel. Two kinds of spherical Nb(C, N) with different size were recognized as the primary and the secondary precipitates of Nb(C, N) which contain different V contents. It was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb(C, N).
关键词:
Heat resistant steel
,
9-12%Cr steel
,
phase transformation
,
microstructure
,
MX precipitate
R.K. Gupta Bhanu Pant Vijaya Agarwala R.C. Agarwala P.P. Sinha
材料科学技术（英文）
Reaction synthesis process has been used to develop γ titanium aluminide using elemental powders. Powder mixture of Ti-48 at. pct Al was prepared in ball mill and reaction synthesis was carried out in hot press with varying temperature and pressure. Titanium aluminide synthesized under high pressure and temperature resulted in better properties with respect to densification, homogenization response, mechanical properties and oxidation resistance as compared to that synthesized under low pressure and temperature. Al rich phases were observed in as-synthesized condition in all the experiments. However, some Ti rich phases were also found in high pressure-temperature synthesized samples. Density, hardness and tensile strength have been correlated with applied pressure through empirical relations. Variation in density with pressure is found to be logarithmic whereas hardness and tensile strength variation with pressure is polynomial.
关键词:
Titanium aluminide
,
Reaction synthesis
,
Reaction synthesis, Phase transformation
