The square Q235B plates which are perpendicular to the rolling direction are bent to different degrees by WDW-200 kN universal testing machine, and the relationship between grain size variation, dislocation movement and neutral layer are studied. The results show that microstructure evolves from lath grain into equiaxed grain, and with neutral layer as the boundary, the outer layer thickness is thinner under the action of external tension when the plate is bent, the thickness of the inner layer increasing under pressure, and under the maximum deflection, the increase of r/t specimen is not easy to crack.

bending deformation  /  neutral layer  /  mechanical property  /  microstructure