Study Of Welding Deformation Behaviors Of C-type Stainless Steel Independent Liquid Tank Of LNG Carrier

Liquified natural gas (LNG) carrier is a kind of high technical, high difficult and high additional value ship, and the tank of loading liquefied natural gas is the most difficult part for construction. The C-type independent liquid tank of LNG carrier adopts a new type stainless steel 304L with good fracture toughness and corrosion resistance at low temperature. However, because of higher thermal expansion coefficient and lower thermal conductivity coefficient, austenitic stainless steel will generate a lot of deformation during welding process, which will affect structure size, precision building and reduce loading capacity etc. It will affect the whole production schedule and manufacture costs if it needs a great deal of time and cost in correcting work of welding deformation. So, prediction and control of structural welding deformation become very important.Firstly, this paper described finite element analysis theory of the welding process and welding simulation realization process by ANSYS. Then the rationality of assumed material properties for 304L stainless steel was verified by experimental study and thermal elastic-plastic finite element method (FEM) analysis of plate surfacing welding. On this basis, thermal elastic-plastic FEM was applied to predict welding deformation of typical parts of tank successfully. Finally, elastic shell element FEM on the basis of inherent strain was applied to predict welding deformation of the local and the whole structure of tank. It put forward measures to decrease the deformation by analyzing the results, which provided a good theory basis to control welding deformation of C-type stainless steel independent liquid tank of LNG carrier.