EFFECT OF DYNAMIC STRAIN AGING ON LOW CYCLE FATIGUE BEHAVIOUR OF 18--8 AUSTENITIC STAINLESS STEEL
动态应变时效对18—8型奥氏体不锈钢低周疲劳行为的影响

Studies were made of the symmetric tensile-compressive low cyclic fatiguebehaviour and dynamic strain aging (DSA) pre-treatment influenced on 18-8 austeniticstainless steel. Within the tested amplitude range of strain: ±0.5%-±1.5%, the three pro-cesses of cyclic hardening, cyclic saturation and cyclic softening were observed. In the sameamplitude of strain, the peak stress of the samples pre-treated by DSA is higher than that ofsolid-solution and cold working pre-treatment, but almost no differences of the fatigue livesof them were found. TEM observation shows that the uniform and stable dislocation net-works with high density form after DSA pre-treatment, which increases the cyclic peak stress.The cyclic softening is resulted from the low dislocation density and elongated cell structurewith low energy.