| Uncontrolled consumption of energy sources and waste o f resources has seriously hampered the development of economy. Welding process is a high energy and resources consumption process. It is an important measure to effectively reduce the waste of energy and resources in welding process. N umerical simulation is a process which can implement virtual physics and chemistry experiment and can get results. It not only can greatly shorten experimental period, significantly reduce production costs and improve production efficiency, but also can achieve repeated simula tions. Then it can get optimal experimental process parameters and programs. And then it is efficient to reduce the waste of energy and resources. The process of laser welding and pressure vessel crack repair welding exist the problem of high energy consumption. Numerical simulation can effectively reduce energy consumption during welding process and the number of welding test to achieve the purpose of low-cost and high- yield.In this paper, the process of laser welding for A304 stainless steel and the process of pressure vessel nonlinear crack repair welding is regarded as the research object. The method of combination welding test with numerical simulation is used to explore the laws of temperature field, flow field and the force in the pool during laser welding process and pressure vessel nonlinear crack repair welding process. It also can reveal how the welding path influencing temperature and flow field of molten pool.The influence of welding speed, laser power and heat source on temperature field during laser welding for A304 stainless steel was discussed. Computational fluid dynamics software was used to simulate distribution law of temperature field and molten pool shape during laser welding for A304 stainless steel. In this study, the impact of welding speed, laser power and heat source on temperature field and molten pool shape during laser welding for A304 stainless steel was discussed. It was found that it presented a transition point in process of the impact of welding speed and laser power on temperature field and molten pool shape. It was with high accuracy that Rotary-Gauss body heat source was used to simulate laser welding process. And simulated molten pool was consistent with test weld morphology.The influence of surface tension and buoyancy on molten pool flow field during laser welding for A304 stainless steel was revealed. Computational fluid dynamics software was used to simulate flow field during laser welding for A304 stainless steel. In this study, the impact of surface tension and buo yancy on molten pool flow field during laser welding for A304 stainless steel was discussed. It was found that buoyancy and surface tension was the main driving force during laser welding process. Driving effect of surface tension is greater than buoyancy. And molten pool was became under the two driving force, then the nail head shape was required, which was consistent with molten pool of laser welding.The law of periodic and symmetry of temperature field and molten pool shape, the impact of welding path on temperature field and the impact of positive and negative surface tension on pool flow field during pressure vessel nonlinear crack repair welding was demonstrated. Computational fluid dynamics software was used to simulate temperature and flow field during the process of A304 stainless steel pressure vessel nonlinear crack repair welding. In this study, the law of periodic and symmetry of temperature field and molten pool shape, the impact of welding path on temperature field and the impact of positive and negative surface tension on pool flow field during pressure vessel nonlinear crack repair welding was discussed. It was found that it presented laws of periodic, axial symmetry and central symmetry in temperature field and pool shape during the process of A304 stainless steel pressure vessel nonlinear crack repair welding. Welding path could change penetration and pool width, and then could change pool shape. The impact of positive and negative surface tension on the size of penetration and pool width was not synchronized. |
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