Study on the Mechanical Properties of Low Carbon Steel under Different Tension-torsion Loading Rate

Based on the tension-torsion composite deformation theory and plane stress state theory,the calculation formulas of the principal stress and its main direction of corresponding to failure of low carbon steel specimen under axial force and torque were deduced.We designed three kinds of experimental programs with different tension-torsion loading rates.By experiments,we had got the time curves of torsion moment of axial force,strain and twist angle.We observed the section characteristics corresponding of the specimen failure and we compared the calculated solution with the experimental results.The reslults indicate that with the increase of loading rate,the elongation of low carbon steel increases and the shrinkage rate decrease;the tensile strength,yield limit and torsional strength are improved;and the principal stress and principal direction value at the time of fracture are also increased.The principal direction of the specimen failure is consistent with the theoretical calculation result.