X80 Grade Steel for New Generation RAN Warships

This paper reports on a joint DSTO/CRC for Welded Structures (CRC-WS) program to investigate the feasibility and potential advantages and challenges of using API X80 Grade steel in warship construction. API X80, a new low cost high performance steel devised for high pressure gas pipelines, is 55% stronger than conventional naval structural steel. Furthermore, it is significantly tougher than conventional naval steel and just as easy to weld. The use of this steel in future naval ship construction should permit the fabrication of lighter structures, with concomitant increase in topside carrying capacity and/or improved centre of gravity with improved sea-keeping performance. Although X80 Grade steel appears to have very attractive potential features for future RAN warship construction, the DSTO/CRC-WS program is essential to validate the technology and assess the potential advantages/disadvantages. This includes, establishing its fabrication response and ultimately fully qualifying X80 steel for shipyard construction. The on-going research program between DSTO and CRC-WS is addressing all these issues. The work presented in this paper covers the following aspects of the work conducted so far: Phase I. Development of a materials and welding technology package to validate the fabrication of X80 steel in future RAN warship construction and also for industry demonstrator purposes. Phase II. Installation of an X80 steel demonstrator panel in the Landing Craft Heavy, HMAS Balikpapan. Phase III. FEA assessment of structural performance and possible weight savings gained through the use of X80 steel in RAN warship superstructures. Phases I and II have now been successfully completed. Whilst Phase III is still on-going, initial results are highly encouraging and indicate that use of X80 in superstructures can result in significant weight savings for superstructures. The paper concludes by giving a brief description of the next steps to be taken in the program.