In situ monitoring the properties of 20 carbon steel and ductile iron under combined tension and three-point bending loadings

This paper is concerned with the bending strength of the materials that is improved under the combined tension and three-point bending loadings. During the tension and three-point bending process, the whole evolution of metallographic structures of the specimens is in situ monitored by the microscope of in situ monitoring module. Moreover, a finite element analysis (FEA) model is established by using ABAQUS to analyze the distribution of stress, when the pre-tensile stress is different, but the deflection of the three-point bending is same, 3.0 mm. The simulation results are consistent with the experiment results. Therefore, it is clearly that the bending strength is increased with the increase of pre-tensile stress, when the bending load is 1750N every time. And the yield point of material is obviously disappeared under combined tension and three-point bending loadings. Meanwhile, the in situ metallographic images verify from the microscopic point of prospective that the bending strength of the material has been improved.