Sutdy Of Double-Side Arc Welding On The Horizontal Position Of The Thick High-Strength Low-Alloy Steel Plate

High-strength low-alloy (HSLA) steels have being used more commonly on the manufacturing of ships. Welding, as its major production method, whose technologies are directly related with the ship-building industry. To the welding of the ship, there are many horizontal position welding, the old way with beveling of the double edges was that-front welding after preheated, then welding after carbon arc air gouging on the contrary side-too much procedures, long production period, low welding quality, large percent of reworks, low productivity. The HSLA steel welding has being a constraint of the ship manufacturing. Therefore, double-side arc welding was brought to the horizontal position welding of the thick HSLA steel plate, the research of its mechanization was doing for the popularization and application of this green efficient welding technology with low cost.First of all, double-side arc welding on the horizontal position was introduced, which choose the low welding parameter, for preventing the molten pool Clifton caused by the effect of gravity. Adopt complex filtration technology to prevent the effect of the arc light, by the dynamic observation of arc and welding pool, get the results that the fusion root is good and the pool is under a partial but not Clifton which are the characteristics of the horizontal welding. The front pool is become longer for the heated action of the back arc. Weld forming is beautiful without Clifton, undercutting, cracks and other defects.The performance is decided to the organization. Not only the chemical composition of materials but the heat process can determine the organization of the weld joint. HSLA steel is sensitive to the heat process. The heat process of double-side arc welding on the horizontal position with the double heat source cycling is very complex. Therefore, heat parameters of the different areas of heat affected zone are collected by thermocouple, and base on which, carry out numerical simulation on the heat process of the poll. Front arc pre-heated the back pass, and the protect gas of the back arc that have the front pass heat-treated also have the back of the front weld.Secondly, the joint experience rapid heating and cooling with physical and chemistry reactions, the solid phase transition process, the gradient of organization is greatly different, and different organizations influence and restriction each others. Therefore by the macro analysis the overall joint performance t is informed. By observing the microstructure and testing the micro hardness, and then analysis the organization types and its performance which influence the whole joint.Finally, some zone of the joint experiencing the double-side arc welding on horizontal position have complex heat processes, and these areas sometimes have small dimensions which restrict the test of their performances. So by the thermal simulation technology, we can get a sample which experiences specific heat treatment and is equivalent to the small area of the joint. Then have the microstructure observation, and analysis the hardness and toughness.The above analysis shows that, horizontal position double-side arc welding on the horizontal position thick plate welding of the HSLA steel is feasible.