遊離フェライト中に硬質領域が存在する鋼の下降伏点

概要

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The influences of microstructural parameters on the lower yield point σ were investigated, in the microstructure containing tempered martensite patches in free ferrite matrix. The results obtained are as follows : (1) σ is not affected by the difference of hardness in the tempered martensite patches. (2) σ rises with the increasing of &fnaf;, the volume ratio of total tempered martensite, when the ferrite grain size α_1 is kept at a constant value. However, σ does not vary, when the mean free path between the tempered martensite patches α_2 is kept at a constant value. (3) There is an approximately linear relationship between (α_1)^<-1/2 and σ in the presence of tempered martensite patches. And the sensitivity of σ to α_1 increases with the increasing of &fnaf;. (4) There is a linear relationship between (α_2)^<-1/2> and σ, and better correlation is demonstrated compared with the relationship between (α_1)^<-1/2 andσ. Furthermore, when the values of &fnaf; are with in the range of 15 to 40 %, the values of σ are plotted on a straight line irrespective of &fnaf;. (5) These results can be understood under the consideration that, in the propagation of Luders band, α_2 is the effective length of slip band to produce the stress concentration for forcing a dislocation out from a boundary of free ferrite and tempered martensite patch, when the tempered martensite patches are contained.
社団法人日本材料学会の論文
1965-07-15