Study On Test And Numerical Simulation Of T-joint Welding Crack

Welded joint is the joint that is formed by the welding connection method. If the weldingjoint is damaged, the strength of whole welding structure will fail. A large number ofengineering cases show that: in most cases, the failure of welded structures is due to damagecaused by welding joint. In this dissertation, considered by two different ways crack test andnumerical simulation, the cause of T-joint full penetration welding transverse crack, thecorresponding solutions are proposed, and it provides the guarantee for the advantage andreliability for marine products and ship welding quality. The research mentality and theprocess of the thesis are as follows:Firstly, according to the crack reproduction and expanded investigation test, routineperformance testing and the anatomy test of crack it is determined that the crack is hydrogeninduced and delayed crack. Through the theoretical analysis of delayed crack, the main factorsto determine the T-joint welding cracks are diffusion hydrogen content of deposited metal,tensile stress, metal plasticity and other factors.Secondly, T-joint welding crack propagation numerical simulation is used by ANSYSsoftware. The main Analysis process is as follows: the resulting stress, strain regularity in thewelding crack occurring, crack stress intensity factor characterized the crack propagation rate,the calculated results using the maximum circumferential stress theory and the comparison. Atlast it is obtained that numerical simulation of welding crack using the ANSYS software isfeasible, and within the range of allowable error.Secondly, through the analysis of many factors, the main factors to determine the T-jointwelding cracks are diffusion hydrogen content of deposited metal, the size of restraint stress,the deposited metal carbon equivalent and chemical composition and field work condition etc.Fourthly, aiming at T-joint welding crack in the work over vessel, appropriate preventivemeasures are taken such as the establishment of a preheating system, optimization methods ofmaterial selection and welding technology, to prevent the welding cracks.In conclusion, the results of this study provide ideas and innovative ways to improve andprevent the welding crack.