Reversing effect of electropulsing on damage of 1045 steel
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Guanhu He and Benlian Zhou Institute of Metal Research and International Center for Materials Physics, Chinese Academy of Sciences, Shenyang 110015, People’s Republic of China (Received 5 October 1999; accepted 10 February 2000)
The influence of electropulsing on the damage of 1045 steel was studied. The results show that electropulsing can substantially increase the strength and ductility of the damaged material, with a little decrease of the Martensite hardness. After the treatment of electropulsing, the microstructure around the crack is modified, and the new structure can prevent the crack from growing. The healing effect of electropulsing on crack is discussed. It is thought that the temperature and thermal compressive stress caused by electropulsing are the main factors causing the healing effect.
I. INTRODUCTION
II. EXPERIMENTAL
Damage is unavoidable during the processing and application of material. As a nonliving thing, material cannot feel and cure the damage itself. The only thing it can do is to bear and accumulate the damage until fracture. Then it is important to research an effective method that can heal the damage or prevent the damage from growing. The method must have two special characteristics: (i) the detection of damage must be automatic, even when the dimension of the injured part is small; and (ii) the effect of repair on the uninjured part must be small enough. Otherwise, this kind of healing is useless or even harmful. For metallic material, electropulsing is a good choice. Electropulsing was chosen for three reasons: (i) electrical conductivity is one of the most structurally sensitive parameters in metallic materials,1,2 and is one of the most important quantities in the interaction between electropulsing and metallic materials;3,4 (ii) the effects of electropulsing on the uninjured part have been proved to be small;5 and (iii) electropulsing is easily controlled and performed in practice. In the past, studies about effects of electropulsing or electric current on metallic materials were mainly focused on four fields: electromigration,6–8 electroplastic effect,9–11 the effect of electric current on the solidification structure,12–14 and the effect of electric current on the structure and properties of amorphous alloys.15–17 Reports about the healing effect of electropulsing on the damage are hard to find. The aim of this paper was to research whether the above problems can be solved or not in the combined system of metallic materials and electropulsing. 1056
http://journals.cambridge.org
J. Mater. Res., Vol. 15, No. 5, May 2000 Downloaded: 19 Mar 2015
The specimens of 1045 steel were heated to 840 °C and then quenched in water to produce cracks. All specimens were divided into three groups: M, MT, and ME. MT were tempered at 600 °C. ME were treated by electropulsing; the pulse duration was 0.2 ms and the experimental voltage was 1.5 kV. M were quenched only and employed as compared specimens. The effective part of tensile specimens was designed as 8.0 × 2.5 × 0.2 mm. The cracks loca
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