塑性加工した純アルミニウムの塑性疲労挙動

概要

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The effect of pre-strain on the behavior of lattice defects during cyclic straining was analysed theoretically. In order to ascertain the propriety of the results obtained, wires of cold worked aluminium were further cyclically strained in torsion with a constant strain amplitude at 77K or R. T. The dislocation density during cyclic straining was given as a function of cumulative strain by [numerical formula] where ρ_m: mean dislocation density, ρ_<pre>: mean dislocation density in pre-strained metal, α_2, β_2: constants. A detailed model for cyclic peak stress vs. cumulative strain response was developed from this equation, on the assumption that the amount of strain hardening is proportional to square root of the mean dislocation density. For cyclic straining with the condition of ρ_<pre>>(α_2,/β_2)^2, the dislocation density decreases gradually with the number of cycles to (α_2,/β_2)^2. Metals therefore show the behavior of fatigue softening. The concentration of point defects C_i in pre-strained metal during cyclic straining at low temperatures such as 77K, is as follows: [numerical formula] were K_1, K_2: constants. The density of lattice defects calculated from the above equations agreed with that estimated through resistivity measurements on fatibued specimens at 77 K.
社団法人日本材料学会の論文
1982-01-15