中文摘要：

研究地磁场环境中钢试件在动拉伸载荷作用下表面弱磁信号的变化以及磁记忆效应．分别进行弹性范围的等幅循环正弦加载和幅值递增至强度极限的正弦加载，对试件表面弱磁场法向分量与正弦加载的循环次数、幅值之间的关系进行了分析．结果表明，弹性加载中低频载荷的循环次数对磁信号增长的影响不明显，而幅值递增加载过程中，当幅值增大至塑性加载范围时，磁信号的变化趋势与弹性加载时相反，且信号绝对值显著增加，最终磁信号的分布在发生颈缩处出现梯度很大的过零．

英文摘要：

Weak magnetic signal changes and metal magnetic memory effects of steel tensile samples under the excitation of geomagnetic field were studied. Two kinds of sinusoidal tensile load cycles were applied on the samples and the magnetic signals changes were recorded. The results indicated that the cycle index did not affect the magnetic signals in elastic loading processes. When loading goes into the plastic range, polarity of the magnetic signals reversed and the magnetic field changed dramatically near the position where necking finally occurred. And the magnetic distribution curves acquired zero value with a large gradient at the position.