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COMPOSITION DESIGN FOR A BEARING STEEL WITH LIMITED HARDENABILITY

L. P. Xu , M. H. Xu , L. Li , Y.A. Min , X.Z Xuand R.H .Liu (Department of Materials Science and Engineering , Shanghai University , Shanghai 200072 , China) (Shanghai No.5 Iron and Steel Factory , Shanghai 200940 , China)

金属学报(英文版)

The composition of a bearing steel was designed for limited hardenability by use of Grossmann's method. A medium frequency induction Process was applied to heat bearings to ensure penetrant heating and suitable solving of carbon and other elements in the matrix. The hardened depth measured from the end quenching test samples and actual bearings matches well with the designed one.

关键词: : bearing steel , null , null

SURFACE REACTION OF Ni_3Al WITH WATER VAPOR OR OXYGEN

YX. Chen , X.J. Wan and W.X. Xu (Institute of Materials Sciences , Shanghai University , Shanghai 200072 , China)(Shanghai Iron and Steel Research Institute , Shanghai 200940 , China)

金属学报(英文版)

The kinetics of the surface reactions of single crystal Ni3Al and polycrystal line Ni3Al0.00052 wt% B with water vapor or oxygen was investigated using XPS. Both reactions initiate at less than 1.5×10-6 Pa.s exposure. The reaction of Ni3Al does not saturote with water vapor at 0.43 Pa.s; with oxygen at 8.4×10-2 Pa.s and the oxide formed is Al2O3. The kinetics of these reactions can be used to eaplain the different ductility behavior of Ni3Al-based alloys in various environment.

关键词: Ni_3Al , null , null , null

THE FAILURE MECHANISM OF REVERSE SHAPE MEMORY EFFECT IN A Cu-BASE ALLOY

C.M Li , G.X. Dong , S.T- Dai , and D. Y Chen (Tsinghua University Beijing 100084 , China)J Yin and D.X. Hu (Shanghai No.5 Steel Works , Shanghai 200940 , China)

金属学报(英文版)

The interior structural evolution accompanying reverse shape memory effect (RSMEin a Cu-Zn-Al alloy was studied by means of transmission electron microscopy. It was found that RSME is closely related to bainitic transformation in this alloy during the isothermal reaction at moderate temperatures. At a given temperature and a certain external constraint stress, the shape memory effect depends mainly on the aging time.During the early stage, the shape memory effect enhances with the increase of reactiotn time. Then it will decrease gradually apon further aging. If the alloy is overaged, the stacking faults of bainite will disappear gradually by the motion of partial dislocations through which long range diffusion of solute atoms takes place, giving rise to the deterioration of RSME. When all the bainite transforms to α phase, RSME will lose completely.

关键词: reverse shape memory effect , null , null , null

A Positron Study of Hysteresis Temperature in Ti-Ni Alloy

Jingcheng WANG and Guiying QIN (Shanghai Key Lab. of Metal Functional Materials , Shanghai Iron and Steel Research Institute , Shanghai 200940 , China)(To whom correspondence should be addressed)Guilin ZHANG ana Wanhui ZHENG (Shanghai Nuclear Research Instit

材料科学技术(英)

For Ti-Ni alloy it is exceedingly difficult to prepare an element that has a desired and defined hysteresis temperature for its preparing process is not pedect at present. Because the mechanism of transformation in Ti-Ni has not been fully clarified, it is far more exceedingly difficult to explain the hysteresis temperature only by using the traditional metal physics techniques., But positron annihilation seems to be a suitable method for it. The positron annihilation measurements showthat the hysteresis temperature may be controlled mainly by the relative fraction of the defectscontained in a two-way shape memory element.

关键词:

Investigation of Nanocrystalline Fe-Cu-Nb-Mo-Si-B Alloy

Yanzhong ZHANG(Shanghai Iron and Steel Research Institute , Shanghai 200940 , China)

材料科学技术(英)

The soft magnetic properties are reported for newly-developed nanocrystalline Fe72.7Cu1Nb1.8-Mo2Si13B9.5 and Fe73Cu1Nb1.5Mo2Si13B9.5. The high frequency core losses of the new alloys are as follows: P3/100K=473 kW·m-3, P2/200K=750 kW·m-3, P2/500K=3400 kW·m-3,P0.5/1000K=680 kW·m-3, which are clearly lower than those of the early-developed Fe-Cu-Nb-Si-B nanocrystalline alloys and the superior power MnZn ferrite H7.4. The dependences ofcore loss on frequency and amplitude magnetic flux density have been analysed. The temperature relations of initial susceptibility have been examined for as-quenched and different annealedFe72.7Cu1Nb1.8Mo2Si13B9.5 alloy and interpreted by using the phenomenological theory.

关键词:

NEWLY-DEVELOPED AND CHEAP NANOCRYSTALLINE Fe-Cu-Nb-Mo-Si-B ALLOYS FOR SWITCHING MODE POWER SUPPLY

Y.Z. Zhang(Shanghai Iron and Steel Research Institute , Shanghai 200940 , China)

金属学报(英文版)

The synthetical soft magnetic properties are reported for newly-developed nanocrystalline Fe73.5 Cu1 Nb0.9Mo2.1 Si13.5 B9 and Fe73.5 Cu1 Nb0.5Mo2.5Si13.5B9 alloys. The levels of high-frequency losses of the new alloys are P3/100k=612 and 670 kWm-3,P2/200k=880 and 973 kWm-3, P2/500k=4300 and 4600 kWm-3, P0.5/1000k=860 and 920 kWm-3, respectively. They are significantly lower than those of the superior power Mn-Zn ferrite H7c.4.The dependences of core loss on frequency and amplitude flux density have been analysed. The practical applications of the new alloys to switching mode power supplies with the output power of 1 and 2 kW are reported.

关键词: nanocrystalline alloy , null , null , null

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