Sumitomo Metals Receives Contribution Award of 41st ICHIMURA Industrial Prize for Development of Steel Plate for Improving the Fatigue Strength in Welded Joints

On April 28, 2009, Sumitomo Metal Industries, Ltd. (Sumitomo Metals) received a Contribution Award of the 41st ICHIMURA Industrial Prize from the New Technology Development Foundation for its development of steel plate for improving the fatigue strength in welded joints, which was titled "Development and commercial application of new functional steel material with an extended fatigue-life."

1.Object for commendation
Previously, the commonly held belief was that the fatigue strength in welded joints cannot be raised with steel plates. However, Sumitomo Metals broke such general assumption. The company developed and commercialized "FCA-W steel plate*," high-tensile-strength plate that delays fatigue crack initiation in welded joints.

2.Details of the development
(1) Development background
Steel structures (plates) that are subjected to repeat loads over many years are susceptible to cracking. This phenomenon is called fatigue fracture. It is said that 80% of the damage to large steel structures is caused by fatigue fracture. A small crack (a fatigue crack) occurs at first and then grows, or propagates. Previously, the commonly held belief was that fatigue crack initiation had to be prevented in the fatigue design of steel structures. However, in 2001, Sumitomo Metals developed steel plates, based on a new design concept that structures could withstand fatigue fracture by controlling fatigue crack propagation. Yet, the fact that the fatigue strength in welded joints could not be raised had remained as a vexing problem. In 2008, Sumitomo Metals developed high-tensile-strength steel plates which function to delay fatigue crack initiation in welded joints to begin with.

(2) Characteristics of "FCA-W steel plate"
In conventional steel plates, the fatigue strength in welded joints has been a weak point. It has generally been thought that the fatigue strength in welded joints was constant, and that this could not be improved with steel plates, no matter what kind of steel plate was used. For this reason, in order to ensure fatigue strength, other methods have been employed, such as increasing the thickness of plates, attaching reinforcement members to welded joints.

Sumitomo Metals developed "FCA-W steel plate," which overcame the general belief. In addition to a function to control the propagation of fatigue crack, this steel plate functions to delay the initiation of fatigue cracks in welded joints.

By simply replacing conventional steel plates in the steel structures to "FCA-W steel plates," the structures can have an extended life and a reduction in weight, without increasing the thickness of plates and attaching reinforcement members.

(3) Contributions
i) The use of "FCA-W steel plate" in welded structures, which are part of social infrastructure, results in prolonged fatigue-life and helps to realize and maintain a safe and reliable society.
ii) These of "FCA-W steel plate" in transportation equipment enables weight reduction and contributes to energy saving and the reduction of CO2 emissions.

3.Future development
The application of "FCA-W steel plate" in automobile chassis, construction machinery, and railway bogie trucks has been under study. Sumitomo Metals has also received requests for its application in offshore structures, wind power generation equipment, and mining machines.

(Reference)
Ichimura Industrial Award
Below is an excerpt from the Purpose of the Award that is stated in the recommendation guidelines for the 41st ICHIMURA Industrial Prize from the New Technology Development Foundation (the original is in Japanese.)
[Purpose of Award]
In commemoration of the Medal with Dark Blue Ribbon, which was awarded to the late Kiyoshi Ichimura, the founder of the Ricoh Sanai Group, on April 29, 1963, the Ichimura Award was established in order to contribute to the development of science and technology and to improvement in their level.
The award is given to researchers who have produced exceptional achievements in developing industrial technology in Japan, with scientific and technical contributions in the subjects of advances in science and technology, industrial development, cultural progress, and the welfare and safety of people.

(Terminology)
* FCA-W (Fatigue Crack Arrester-W) steel plate
The "W" of "FCA-W steel plate" stands for both "weld" and "double," which refers to the plate's two functions: controlling fatigue crack propagation and delaying the initiation of fatigue cracks in welded joints. The mechanical properties other than fatigue resistance, and basic performance as steel plate, including weldability and workability, are equal to, or higher than general high-tensile-strength steel plate.

from left
Mr.Jiro Ushio, Chairman, The New Technology Development Foundation
Mr.Kazushige Arimochi, Senior Consultant, Corporate Research & Development Laboratories, Sumitomo Metal Industries,Ltd.
Mr.Akinori Inami, Manager, Steel Plate Technology Department, Sumitomo Metal Industries,Ltd.
Mr.Noboru Konda, Senior Research Engineer, Corporate Research & Development Laboratories, Sumitomo Metal Industries,Ltd.