Effect of pre-bending deformation on mechanical properties of complex phase steel CP800

Abstract

The pre-bending specimens were obtained by stamping with complex phase steel CP800, and the effect of pre-bending deformation on microstructure, residual stress and mechanical properties of the steel were studied by using EBSD, X-ray residual stress measurement system, tensile testing machine,DIC technique, etc. The results show that the distribution of residual stress of pre-bending specimens exhibits stress distribution of tension-compression-tension-compression, which means that the inside surface (compression layer) is tension stress and outside surface (tension layer) is compression stress. Such special distribution leads to a 16% reduction of yield stress of specimens after pre-bending. Meanwhile, due to the dislocation strengthening and hardening caused by cold deformation, the elongation of material decreases by 25% and the tensile strength increases by 24% after pre-bending. Furthermore, it is found that the inside surface produces greater plastic strain and is broken earlier than the outside surface due to the existence of tensile residual stress.

Keywords

• complex phase steel
• pre-bending
• residual stress
• surface strain field
• mechanical property