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Effect of electric current pulse on mechanical properties of ultra high strength steel 1180CP

Effect of the pulse electric current on mechanical properties of an ultra-high strength steel (UHSS) is experimentally investigated. A single pulse of electric current with a short duration of 0.36 sec is applied to the specimen under tensile plastic loading. The experimental result showed that flow stress of the UHSS nearly instantly drops at moment of electric current, following strain hardening until necking of the specimen. Uniform elongation completely depends on the pulsing strain, while ultimate tensile strength slightly changes after electric current. | Journal of Science and Technology 54 (5A) (2016) 82-90 EFFECT OF ELECTRIC CURRENT PULSE ON MECHANICAL PROPERTIES OF ULTRA-HIGH STRENGTH STEEL 1180CP Nguyen Trung Thien1,*, Sung-Tae Hong2 1 Center of Mechanical Technology Training & Practice, Hung Yen University of Technology and Education, Dan Tien, Khoai Chau, Hung Yen, Viet Nam 2 School of Mechanical Engineering, University of Ulsan, 93 Deahak-ro, Nam-gu,Ulsan, South Korea * Email: trungthienckc@gmail.com Received: 15 June 2016; Accepted for publication: 6 December 2016 ABSTRACT Effect of the pulse electric current on mechanical properties of an ultra-high strength steel (UHSS) is experimentally investigated. A single pulse of electric current with a short duration of 0.36 sec is applied to the specimen under tensile plastic loading. The experimental result showed that flow stress of the UHSS nearly instantly drops at moment of electric current, following strain hardening until necking of the specimen. Uniform elongation completely depends on the pulsing strain, while ultimate tensile strength slightly changes after electric current. Keywords: electric current, ultra-high strength steel, mechanical property. 1. INTRODUCTION In recent years, ultra-high strength steels (UHSS) with a tensile strength higher than 1 GPa, often up to 1.8 GPa, have been increasingly selected in the automotive industry due to their outstanding advantages including high crashworthiness, high strength to weight ratio, excellent weld ability, and cost effectiveness [1]. The use of UHSS in structural areas such as pillars, bumpers, and front cross-members can make automotive frames much stronger, stiffer, and lighter than those made of conventional steels. However, UHSS generally show low formability and high spring back, which make it difficult for automakers to manufacture UHSS automotive parts in desired shapes with an affordable cost. Therefore, it is natural that a huge demand exists in the automotive industry for a cheap and .