High Arrestability Type Yield-Stress-47kg High-Strength Steel Plate Has Applied to Large Container S

Nippon Steel’s high crack-arrestability type yield-stress-47kgf/mm2 high-strength steel plate (“YP47kg -steel”) has been adopted for large container ships (the order of Kawasaki Kisen Kaisha， Ltd.， carrying 4，500 containers each， 10 ships in a row) built by Hyundai Heavy Industries， Korea， which is the largest shipbuilder in Korea. This is the first case that YP47kg-steel being used for ships for construction by an overseas shipbuilder.

YP47kg-steel， combining crack-arrestability (toughness) with strength， has been developed for increasing in size of container ships by Nippon Steel jointly with Mitsubishi Heavy Industries， Ltd. By using the high-arrestability-type steel plate for the hatch-side coaming and the upper deck， which are the most important parts for a ship’s structural strength， even in the event of brittle fractures occurring in the hull， cracking can be arrested in the parts， thus securing even higher levels in a vessel’s structural integrity and safety. This high strength steel plate also contributes to down-gauging and down-weighting and the resulting greater fuel economy. This steel plate also makes it possible for a container ship to be loaded with more containers.

All such performance of YP47kg-steel has been recognized. Since it was adopted last year for the series of six large container ships， carrying 8，100 containers each， (being built at the Nagasaki Shipyard and Machinery Works of Mitsubishi Heavy Industries. MOL CREATION， the first of the six-vessel series has already gone into service in June of this year.)， it has already been used for about 30 container ships within Japan and abroad， including the large order from Hyundai this time.

To respond to the growing demand mainly on the shipbuilding and energy field， Nippon Steel has been making large investments in the plate mill of the Oita Works， while also implementing measures for enhancing the capacity for high-grade steel plates. This order of Hyundai is a timely case met by our readiness. With our advanced technology and process capabilities， Nippon Steel intends to aggressively work toward increasing demand for high-grade steel plates.


Note 1: “the crack-arrestability”
The ability to arrest cracking. Once cracking occurs， it propagates at a rate of about 1，000m/sec.， instantly causing a structural failure in some cases. Structural integrity is enhanced by the use of steel plate that is given high crack-arrestability.

Note 2: “the hatch-side coaming and the upper deck”
Both are most important parts that are subjected to enormous forces. YP47kg-steel used for the hatch-side coaming and YP40kg steel used for the upper deck in the Hyundai order are given high crack-arrestability. YP47kg-steel has successfully become practical for the first time in the world by joint efforts of Mitsubishi Heavy Industries and Nippon Steel. As in the case of MOL CREATION， the high-arrestabilitiy-type YP40kg-steel is also now available from just only Nippon Steel.

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