서강대학교

초록/요약

Pipes are fabricated using the ERW (Electric Resistance welding) tube mill, and its manufacturing line shows the distribution of yield stress along the circumferential direction. The quality of the tube is strongly dependent on the magnitude as well the distributions of yield stress, so it is essential to consider the Bauschinger effect into the numerical model. This paper presents a numerical model, which uses the modified Yoshida-Uemori kinematic hardening model for an accurate prediction of yield stress in ERW pipes. Subsequently, the model parameters were obtained with the help of cyclic loading test experimental measurements. The proposed numerical simulation comprises the systematic and the successive procedures of a roll forming and a sizing process as it can be done in a series of stages during the simulation process. The influence processing parameters of yield stress, such as, the sizing ratio, the elongation and the thickness, were numerically investigated. The numerical results, which are the thickness distribution and the yield stress, at selective pipe locations were validated with the experimental results. The validation results reveal that the elongation parameter has the more influence in the sizing process, and also we observed that the reduction of elongation results in the decrement on yield stress. From these results, we conclude that the yield stress can be increased by the equivalent plastic strain and the back stress. As well the yield stress of the pipe can be adjusted by regulating the process parameters in the ERW tube mill line.