在脉冲电流作用下钢中裂纹的愈合

对含有人工预置贯穿裂纹的钢进行脉冲电流处理．在光学显微镜和扫描电镜下观察了处理前后钢样品中裂纹和组织的变化．结果表明，脉冲电流处理可以使裂纹的局部在固态下愈合．愈合是在极短时间内发生的，不影响材料不含裂纹部分的原有结构．在电流通过裂纹时产生的较高温度使其有比较大的膨胀量，周围温度较低基体的约束导致向着裂纹内的压缩，从而使裂纹面上的原子重新成键接合．

Experimental study on crack healing in steel using electric current pulse technique

A test was carried out by using electric current pulse in order to heal a through thickness precrack in steel. An optical microscope and a scanning electron microscope (SEM) were employed to examine the change of the crack and the microstructure before and after the healing treatment. The results show that the crack can be partly healed by electric current pulse even in the solid-state, and the healing process is produced within a very short duration. The original microstructure in the area without crack was not changed during the healing treatment. At the areas that the current flows through the crack, the thermal expansion of the material is large due to the high regional temperature. Since it is restricted by the cool matrix, the direction of expansion is to the inside of crack, then the two sides of crack are close to each other. In combination with a high regional temperature, the crack can be healed when their distance is small enough.