LI Qingsheng
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(Chingshen Li)Taiyuan University of Technology
,
Taiyuan
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China T.BRETHEAU Laboratory PMTM
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CNRS
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University Paris Nord Dept.of Mathematics and Mechanics
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Taiyuan University of Technology
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Taiyuan 030024
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China
金属学报(英文版)
The effect of grain boundaries on cyclic deformation and fatigue crack growth in aluminum bicrystals has been studied.The effect of a grain boundary is restricted in a narrow area, termed as grain boundary affecting zone(GBAZ),where the incompatible plastic strain treats internal stress which conversely promotes inhomogeneous slip in the area and grain boundary cracking.As an extended stage I crack initiated from a notch approaches the grain boundary under a constant cyclic stress,the crack front branches splits into several pieces, meanwhile,the growth rate of the crack reduces to a minimum value at the center of the GBAZ.Such microstructure-sensitive growth of extended stage I cracks is mainly attributed to the grain boundary-induced crack tip sheilding.
关键词:
compatibility
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Z.H.Li
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X.P.Liu
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Y.Gao and Z.Xu Research Institute of Surface Engineering
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Taiyuan University of Technology
,
Taiyuan 030024
,
China
金属学报(英文版)
It, ageing high speed steel (AHSS) with high cobalt, has a strong ability of age hardening. However, it has two disadvantages, One is short of toughness, the other is its high price because of its too much alloy content especially cobalt. All of these effect on its widespread using. Now there is a new method without the two flows to form this steel in the surface of ingot iron by use of double glow plasma surface alloying technique.In this paper, the following three parts are introduced: the metallurgical process of this surface ageing high speed steel (SAHSS), the micro structure of the alloying layer, the alloy distribution in the layer. By using the designed source pole, the special alloying process, the required surface alloying content, just like the AHSS—Co23W11Mo7 can be achieved in the surface layer. This new method has wide prospect in the fields of tools, moulds and other wear resisting fields.
关键词:
SAHSS
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