Research On Welding Procedures Of TMCP High Strength Structural Steel For Hull

As the development of technology, ship's main dimensions has been continuously increased and the percentage of high tonnage vessels has been enlarged, in order to improve shipbuilding quality, decrease weights of hull structure and raise loading weights, the high strength low alloy steel for shipbuilding have been increasingly used. High effect and large line energy automatic welding is applied everywhere which accelerates the development of ship-use high strength steel, as a result of the coming of TMCP steel.Firstly, based on theoretical study, this paper also takes the welding of EH36-TMCP high strength hull structure steel which is approved by CCS with a thickness of 25mm as a studying object to present tests and study for its welding technology. Respectively, it adopts welding techniques as double sides submerged arc automatic welding,vertical air backing welding,CO2 backing single side welding,single side submerged arc automatic welding (FCB method) and sets different parameters of welding technology, which are assessed according to metal welding assessing methods as specified by CCS and completely meet the requirements. Mechanical tests (tensile test, bending test and impact test) were carried out to study on its weldability; and microstructures of weld metal, fusion zone, HAZ and fractography were investigated by means of light microscopy and; the effect of processing factors and microstructures of welding joint on strength and toughness of welding joint was analyzed.At the end of this paper,12mm thick E-steel and EH36 for hull have been welded by means of laser welding with cold wire. At the same time,according to some rules of CCS,we try on materials'impact,bend and tensile. Also we do some research for welding materials' mechanical properties, macroscopical structure and microcosmic tissue.