Abstract: In order to dig out the carrying capacity of the material, small strain cyclic loading test are carried out on Q235, which is commonly used for welded structure. Through the test, stress-strain curve and characteristic are obtained under small deformation cyclic loading, and the change rule of stress along with cyclic time is summarized. Moreover, the corresponding calculation models are put forward. The experimental results show that Q235 shows cyclic hardening behavior and Bauschinger effect under symmetrical small strain cyclic loading, and cyclic hardening rate and Bauschinger energy parameter change rate will all reach a different stable value with the increase of number of cycles. Under asymmetric small strain cyclic loading, the deformation behaviour of Q235 can be looked as the response to the superposition of initial strain value and symmetrical strain cyclic loading. And with the increase of number of cycles, the peak stress and yield stress will return to the corresponding value under the symmetrical strain cyclic loading at the same amplitude.

Key words: Bauschinger effect, small deformation, strain cyclic loading, yield platform, yield stress