800MPa级低合金高强度钢的循环软硬化特性

Cyclic Softening/Hardening Characteristic of a High-Strength Low-alloy 800MPa Grade Steel

在不同应变级别控制下，研究了800MPa级低合金高强度钢10CrNiSMoV轴向加载低周循环软硬化特性，研究结果表明：应变加载级别不同，材料表现出不同的循环软硬化特性，当应变幅在0．4％～1．0％范围变化时，材料表现出循环软化的特性，且应变幅越大，循环软化速率越高；当应变幅在0．30％-0．40％范围变化时，材料表现出先硬化，再趋于循环饱和，再轻微循环软化直至断裂的特性。采用透射电镜观察了不同应变级别下试样断口的位错形态，用位错理论解释了产生上述现象的原因。

Under the control of different strain amplitudes, cyclic softening and hardening characteristic of high- strength lowalloy 800MPa grade 10CrNi5MoV steel at axial loading was studied. The experimental results manifested that the steel shows different cyclic softening and hardening characteristic by loading at different strain amplitudes. When stain amplitude changes from 0.30% to 1.0%, the steel indicates cyclic softening feature and the strain amplitude is higher,the cyclic softening rate is quicker and when strain amplitude changes from 0.30% to 0.40%, the material indicates a specialty of hardening, cycle saturation, slightly softening, fracture. Dislocation state of specimens at different strain amplitudes was observed under TEM and the above cyclic softening and hardening phenomena was analyzed by dislocation theory.