The high-strength intermediate shaft, Kobe Steel’s steel forged product for ships, was adopted by International Association of Classification Societies (IACS) for the first time.
Kobe Steel’s high-strength intermediate shaft for ships, a “Specially Approved Material” by Nippon Kaiji Kyokai, has been adopted by Unified Requirements (UR) of International Association of Classification Societies (IACS) for the first time. Thus, the shafts of higher strength can be included into the categorization of materials design, which is favorable for the technology development in terms of energy conservation, thereby improving the environmental performance of the ships and fuel efficiency.
An intermediate shaft is an important component that transmits power from the engine to the propeller shaft. Engines on ships tend to adopt a low-speed, high-torque rotation design to achieve high output and high efficiency. To suppress torsional vibration in the intermediate shaft that occurs when the engine rotates at low speed, shafts of high strength are required.
The original regulation of IACS UR, which requires material design for intermediate shafts have a maximum tensile strength of 800MPa, has restricted the strength to be further intensified. By means of an appropriate alloy composition design and the high purity steel production technology, Kobe Steel realized a steady production of high-strength steel up to 950MPa. In the first half of 2014, Japan’s ship classification society, Nippon Kaiji Kyokai (also known as ClassNK), had qualified the steel forged product as a “special approved material.”
With the same diameter, high-strength intermediate shaft will have better performance in coping with large torsional vibrations than shafts made from traditional materials. If the torsional vibration is the same, high-strength intermediate shaft will have a smaller diameter, thus reducing the weight of the shaft.
From: World Metals