Development Of Heavy Thickness And High Strength Steel Plates For Racks Of Offshore Platform

With the increasing demand of global oil consumption,the development of marine oil and gas has become an important energy strategy for all countries.In various offshore platforms for offshore oil development,jack-up platforms play a great role in marine exploration and development at home and abroad,especially in offshore oil exploitation.The jack-up platform mainly adopts the gear and rack lifting method and the lifting racks mainly adopt the ASTM A517 GrQ Mod/ASTM A514 GrQ Mod high strength and heavy thickness steel plates.At present,we need to import steel plates for racks to build offshore platform.Early development of this steel plate to meet the needs of the domestic market has great social benefits and good technological prospects.So,this paper is based on the cooperative project of development of Heavy Thickness and High Strength Steel Plates for Racks of Offshore Platform which is Shagang collaborated with Jiangsu Sunan Heavy Machinery Technology Co,Central Iron and Steel Research Institute.Systemic research of key technologies and problems in rolling and heat treatment for heavy thickness plate is done in this paper.The main contents and results of this paper are as follows:(1)The deformation on the center of slab can be greatly improved by the large reduction rolling.Using whole course large reduction,the deformation on thickness is basically uniform,The Z direction characteristic is greatly improved.(2)Quenching cooling rate has a great influence on the structure and properties of steel plates.With the increase of cooling rate,the fraction of granular bainite decreases and that of martensite increases in the cooling rate range of 0.05?2?/s,which results in higher strength and toughness.(3)A remarkable grain refinement of prior austenite can be obtained by double quenching,which can improve the strength and toughness.(4)The micrographic structure of the test plate is uniform,fine and stable.There is no obvious difference in the thickness of the steel plate.The grain size is over 7.5.Low temperature toughness and weldability,which meet the technical requirement of racks of jack-up rigs.(5)Shagang has developed 177.8mm ASTM A517GrQ Mod/ASTM A514GrQ heavy thickness steel plates for rack of jack-up rigs by using advanced equipment and technologies.The steel has been approved by ABS,CCS and DNV.Lloyd's Classification Society of Germany.