A new method called node dynamic relaxation is proposed to simulate multilayer welding. A two dimensional plane strain model for multilayer welding is simulated and the results show that mesh distortion can be decreas...A new method called node dynamic relaxation is proposed to simulate multilayer welding. A two dimensional plane strain model for multilayer welding is simulated and the results show that mesh distortion can be decreased, and it is also found that the node dynamic relaxation is a kind of method to calculate welding deformation accurately by comparing experiment results with simulation results.展开更多
During the first welding process in manufacturing a precise seam container, the steel material must first undergo a full annealing treatment. Multilayer welding operations are conducted and then applied with refining ...During the first welding process in manufacturing a precise seam container, the steel material must first undergo a full annealing treatment. Multilayer welding operations are conducted and then applied with refining treatment to obtain the goal by hardening. The influence of thermal refining on mechanical properties of annealed SAE 4130 by multilayer GTAW （gas tungsten arc welding） was discussed. The AW （annealing＋welding） and AWST （annealing＋welding＋solution＋tempering） occurred with a minimum hardness value at GGHAZ （grain growth heat affected zone） due to coarse grain growth~ the hardness occurred with sudden drops between the multilayer welding, but was still larger than the minimum value at HAZ （heat affected zone）. The welded joint efficiency of the AWST was 89.9%, with the elongation reduced to 77.2% of AST （annealing＋solution＋tempering）. The cross section of the tensile samples both appeared with a uniform dimple-shaped structure, and however the necking for AST was greater than that for AWST. The impact value for AWST was 166.5% of AST. Moreover, from microstructure observations, it was found that AWST had a greater tendency to ductile failure than AST. These results can be inferred., the process of steady pressure and the initial position of the precision tube breakage HAZ. However, when stress occurs instantly, HAZ can absorb more energy, therefore the initial damage does not occur.展开更多
The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, l...The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.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
文摘A new method called node dynamic relaxation is proposed to simulate multilayer welding. A two dimensional plane strain model for multilayer welding is simulated and the results show that mesh distortion can be decreased, and it is also found that the node dynamic relaxation is a kind of method to calculate welding deformation accurately by comparing experiment results with simulation results.
基金Item Sponsored by National Science Council(NSC 98-2221-E-212-009-MY3)Ministry of Economic Affairs(99-EC-17-A-16-SI-127),Taiwan,China
文摘During the first welding process in manufacturing a precise seam container, the steel material must first undergo a full annealing treatment. Multilayer welding operations are conducted and then applied with refining treatment to obtain the goal by hardening. The influence of thermal refining on mechanical properties of annealed SAE 4130 by multilayer GTAW （gas tungsten arc welding） was discussed. The AW （annealing＋welding） and AWST （annealing＋welding＋solution＋tempering） occurred with a minimum hardness value at GGHAZ （grain growth heat affected zone） due to coarse grain growth~ the hardness occurred with sudden drops between the multilayer welding, but was still larger than the minimum value at HAZ （heat affected zone）. The welded joint efficiency of the AWST was 89.9%, with the elongation reduced to 77.2% of AST （annealing＋solution＋tempering）. The cross section of the tensile samples both appeared with a uniform dimple-shaped structure, and however the necking for AST was greater than that for AWST. The impact value for AWST was 166.5% of AST. Moreover, from microstructure observations, it was found that AWST had a greater tendency to ductile failure than AST. These results can be inferred., the process of steady pressure and the initial position of the precision tube breakage HAZ. However, when stress occurs instantly, HAZ can absorb more energy, therefore the initial damage does not occur.
文摘The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.
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.
