Metal Magnetic Memory Testing of X60 Pipeline Steel under Tension Load and Fatigue Load
To study the relation between stress and the Metal Magnetic Memory Testing (MMMT) signal Hp(y) of ferromagnetic structure, a material mechanics experiment using X60 pipeline steel specimens under tension load and fatigue load is performed. The results show: The value of MMMT signal in elastic stage is small under tension load, while the value of MMMT signal in plastic stage is large. In the process of static tension, the zero crossing point (ZCP) of initial MMMT signal curves shift to the fracture position, and there is only one ZCP of MMMT signal curve at the position of fracture area. In the process of low-load fatigue, the shape and distribution of MMMT signal curves are similar under different cycle numbers of fatigue load. The value of MMMT signal increases a little with the increase of cycle number of fatigue load, and then increases sharply when the specimen is to be fractured. There is only one ZCP of MMMT signal curve at the position of fracture area in the process of fatigue loading.