Sumitomo Metals Receives Nippon Keidanren Chairman’s Innovation Prize from the Japan Institute of Invention and Innovation for its "Innovation of Steel Plate that Extends Fatigue-Life of Welded Steel Structure"
Today, Sumitomo Metal Industries, Ltd. (Sumitomo Metals) received the Nippon Keidanren Chairman’s Innovation Prize from the Japan Institute of Invention and Innovation (JIII) at the 2012 National Commendation for Invention Award Ceremony* held by JIII, for "Innovation of steel plate that extends fatigue-life of welded steel structures." At the same time, Hiroshi Tomono, President of Sumitomo Metals, was awarded the Invention Practice Service Prize.
1．Summary of the Invention
The innovation given the award is technology regarding steel plates that with metallographic control prolong fatigue resistance of welded steel structures. This innovative material design has more than doubled the fatigue-life of the material compared to conventional steel. This has been made possible by raising fatigue crack propagation resistivity while maintaining similar or more strength, toughness, and weldability. We improved the fatigue strength in welded joints by precisely controlling chemical component of steel.
2．Background
① Controlling fatigue crack propagation
Conventional steel structures that are subjected to repeated loads over many years are susceptible to fatigue fracture. It begins as a micro crack which could eventually propagate to a fracture. The conventional research and development focuses on preventing initiation of micro fatigue crack. Contrary to this, in 2001 Sumitomo Metals developed FCA (Fatigue Crack Arrester) steel plate that withstands fatigue crack by arresting propagation of fatigue fracture after it has been initiated.
② Controlling initiation of fatigue cracks in welded joints
Another general belief was that the fatigue strength in welded joints was constant and that this could not be improved by material design of steel plates. For this reason, in order to ensure fatigue strength, other methods have been employed, such as increasing the thickness of plates and attaching reinforcement members to welded joints. Sumitomo Metals’ “FCA-W steel plate,” which merited the above award, has broken down such a consensus. This high-tensile thick steel plate has also enabled control of the initiation of fatigue cracks in welded joints.
3．Future development
The "FCA-W steel plate" has been used for building bridges and ships and has simultaneously realized prolonged fatigue life and weight reduction. In the case of shipbuilding, the FCA-W plate enables extension of the life of the adopted area without attaching reinforcement materials and thereby reduces the weight of the ship’s structure and helps improve fuel efficiency. We intend to broaden its application to offshore structures, construction materials, and various other welded steel structures , as it will help to realize and maintain a safe and reliable society for us, in addition to contributing to energy saving and global environmental preservation through weight reduction.
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