Abstract:
It seems relevant to restore the continuity of metals and alloys by healing cracks in them with the help of strong pulses of electromagnetic field. This allows you to increase the reliability and extend the service life of materials and products made from them. Although the electric pulse effect is of great practical importance, a method has not yet been developed that would allow healing the largest volume (length) of the defect. It is especially difficult to heal long macro cracks in thin plates by welding their edges using electric pulse action. The purpose of this work is to study the possibility of selecting an electric pulse mode to solve this problem. A method is described that makes it possible to heal long microcracks in flat samples. It is a multi-stage electric pulse treatment. Thanks to this method, it was possible to heal a significant part of the long fatigue macrofracture in the steel plate. Studies of the microstructure of the samples, which were carried out in cross sections, confirmed the healing mechanism. It consists in welding the edges of the crack using molten material. In order for this to happen, the significant compressive stresses and high temperatures were simultaneously created at the crack tip during the pulse, which led to the melting of the steel. Experiments have revealed significant differences in the healing processes along the length of the macrofracture and in depth. However, the healing quality improved with increasing distance from the plate surface. In the healing area, elongated grains and a central zone with equiaxed grains can be observed along the edges of the crack.
Keywords:crack healing, steel, high density electric pulse.
Fulltext:
PDF file (1435 kB)