Funct. Mater. 2020; 27 4: 723-729.


The effect of sign variable bending on structural damage to low-carbon steel

A.A.Briukhanov, N.A.Volchok, S.I.Iovchev, D.A.Dyachok, G.Gershtein, Z.A.Briukhanova

South Ukrainian National Pedagogical University named K.Ushinsky, 26 Staroportofrankovskaya Str., 65020 Odesa, Ukraine


The formation and change in the structure of microdamages during successive deformations by tension and compression in the sheets of low-carbon single-phase steel DC04 (0.06 % C, up to 0.35 % Mn, up to 0.40 % Si, ~ 0.025 % S and P) during alternating sign variable bending (SVB) were studied. The deformation of the annealed bands at the initial stage (0.25 cycles) leads to the formation of a structure with microdamages in the form of pores in the stretched region, to decreasing in the frequency (ν) of natural vibrations of rectangular samples and normal elastic modulus (E). Straightening of the steel strips (deformation of the 0.5 cycle SVB) leads to the degradation of damages formed at the previous stage of the SVB in the stretched region of the strips, which is repeated with each straightening of the samples. The damage coefficient (D) increases with bending and returns to a value close to the previous one after straightening the strips. Changes in D with a change in the tension - compression strain occur intensively in the initial stages of SVB (0.251 cycles). With an increase in the SVB deformation to 10 or more cycles, the level of degradation of damage during straightening of the samples decreases, and the damage coefficient decreases slightly. Damages accumulate in the form of pores that do not undergo changes when the type of deformation changes.

deformation, alternating bending, damage, structure, Young's modulus, degradation.
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