In this paper, detailed information on mechanical properties and test results of Charpy impact test of SBHS400 are provided. As a new steel material standardized by JIS in 2011, little research has been conducted on this topic. Tensile strength, yield strength, weldability and toughness of SBHS400 are compared with its parallel conventional steel SM490Y based on their specifications and the previous experimental studies. Additionally, Charpy impact tests are conducted on specimens made of both SBHS400 and SM490YB under temperatures including low temperatures, in order to understand the superior toughness of SBHS400 in comparison to the conventional 490MPa grade steel.
New steel materials for bridge structures have drawn great amount of attentions across the globe. Steel materials with improved mechanical properties and easier manufacturing processes are strongly pursued. In the light of this situation, Steels for Bridge High Performance Structure (SBHS) was introduced in Japan for its mechanical properties such as high yield strength, improved toughness and weldability, etc. Following by the JIS (Japan Industrial Standards) standardization of the other two available types, SBHS500 and SBHS700 in 2008, SBHS400 was also included in the standard in the year of 2011 (JIS G3140, 2011). As the name indicates, SBHS has minimum yield strength of 400 MPa, 500 MPa and 700 MPa correspondingly. Generally speaking, higher strength steel results in a lighter structure, which reduces the amount of material and lowers the erection and transportation cost. However, one main problem with conventional high strength steel materials due to the increased carbon and alloy contents is the decreased weldability and fabricatability. To make up for the disadvantages, chemical composition of SBHS is well balanced to ensure good weldability and workability while maintaining high material strength.
Previous investigations on tensile strength, load carrying capacity and residual stress of SBHS500 were conducted (Hashimoto, Ono and Okada, 2013; Ono, Ishikawa, Hashimoto and Okada, 2015; Ono, Adake, Kato, Kitane and Matsumura, 2016). Comparing with SBHS500, which has relatively earlier implementation on bridges in Japan, there is a lack of experimental studies pertaining to the mechanical properties of SBHS400. Due to the current lack of information required by the structural analysis for the use of SBHS400, the purpose of this study is to gather comprehensive information such as mechanical, chemical and Charpy absorbed energy of this relatively new steel material. The features of SBHS400 can be understood more distinctively with a comparison to the conventional steel of the similar tensile strength based on their design specifications and the previous experimental studies. Moreover, the Charpy absorbed energy of SBHS400 and SM490Y are compared through experimental investigations, which leads to further understanding of the superior toughness of SBHS400 in comparison to the conventional 490 MPa grade steel.
