It has been widely studied about the final residual stress and deformation in muhipass welding of thick weldments. But there is a lack of a clear understanding of the interrelationship of interpass stress and deformat...It has been widely studied about the final residual stress and deformation in muhipass welding of thick weldments. But there is a lack of a clear understanding of the interrelationship of interpass stress and deformation during multipass welding. In this study, a three dimension numerical model of a sixteen-pass double V-groove welded joint with 50 mm plate is developed to compute the stress field and deformation by using multiple CPU parallel processing technology. The following factors such as the non-linear of temperature, heat radiation, filling of material step by step and so on are considered. Distribution and evolution law of welding stress in the transverse and longitudinal section is analyzed in this paper, and the interpnss stresses are studied also. At the same time the evolution course of angular deformation amount is analyzed, and the experimental results show that the calculated resuhs accord with the measured results of angular deformation.展开更多
In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechani...In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechanics tests. Impact testing of thermal simulated specimens showed that the primary weld metal and the fine gmmed weld metal had good toughness, while the coarse grained weld metal had the lowest toughness value as the local brittle zone (LBZ) in multipass weld metals. Cleavage fracture in CTOD testing of thick multipass weld metals was initiated from martensite-austenite (MA) phases in the LBZ. MA phases were distributed at the prior austenite grain boundaries and around ferrite grains. As the size of the local brittle zone along the fatigue crack front increases, CTOD frncture toughness of multipass weld metals decreases. The weakest link theory was used to evaluate effect of the local brittle zone on fracture toughness of thick multipass weld metals. The estimated curves agree well with the eaperimental data.展开更多
Two main methods, inactive eiement method and quiet element method, to simulate the process of multilayer ：and multipass welding：were reviewed, and the shortcomings of both methods were diScussed as well Based on ...Two main methods, inactive eiement method and quiet element method, to simulate the process of multilayer ：and multipass welding：were reviewed, and the shortcomings of both methods were diScussed as well Based on these analyses, a method called node dynamic relaxation method was put into forward to simulate the multilayer and multipass welding process, and the principle and application of this method were discussed in detail. The simulating results show that using the node dynamic relaxation method can decrease mesh distortion, improve calculation efficiency, and obtain good simulation results. This method can also be used in the field of simulation addition or removing materials in finite element analysis.展开更多
基金National Natural Science Foundation of China (No. 50775053, 50675046)
文摘It has been widely studied about the final residual stress and deformation in muhipass welding of thick weldments. But there is a lack of a clear understanding of the interrelationship of interpass stress and deformation during multipass welding. In this study, a three dimension numerical model of a sixteen-pass double V-groove welded joint with 50 mm plate is developed to compute the stress field and deformation by using multiple CPU parallel processing technology. The following factors such as the non-linear of temperature, heat radiation, filling of material step by step and so on are considered. Distribution and evolution law of welding stress in the transverse and longitudinal section is analyzed in this paper, and the interpnss stresses are studied also. At the same time the evolution course of angular deformation amount is analyzed, and the experimental results show that the calculated resuhs accord with the measured results of angular deformation.
文摘In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechanics tests. Impact testing of thermal simulated specimens showed that the primary weld metal and the fine gmmed weld metal had good toughness, while the coarse grained weld metal had the lowest toughness value as the local brittle zone (LBZ) in multipass weld metals. Cleavage fracture in CTOD testing of thick multipass weld metals was initiated from martensite-austenite (MA) phases in the LBZ. MA phases were distributed at the prior austenite grain boundaries and around ferrite grains. As the size of the local brittle zone along the fatigue crack front increases, CTOD frncture toughness of multipass weld metals decreases. The weakest link theory was used to evaluate effect of the local brittle zone on fracture toughness of thick multipass weld metals. The estimated curves agree well with the eaperimental data.
文摘Two main methods, inactive eiement method and quiet element method, to simulate the process of multilayer ：and multipass welding：were reviewed, and the shortcomings of both methods were diScussed as well Based on these analyses, a method called node dynamic relaxation method was put into forward to simulate the multilayer and multipass welding process, and the principle and application of this method were discussed in detail. The simulating results show that using the node dynamic relaxation method can decrease mesh distortion, improve calculation efficiency, and obtain good simulation results. This method can also be used in the field of simulation addition or removing materials in finite element analysis.
