A 2-DIMENSION CELLULAR AUTOMATON MODELLING OF GTAW SOLIDIFICATION MICROSTRUCTURE
Weld joint microstructure and welding grain size exert a strong influence on the mechanical properties of welds. Equiaxed solidification is wanted to enhance in welding process. These features make it clear that a better knowledge of the columnar-to- equiaxed transition (CET) is of great technical and economical importance. So, prediction of the formation of the microstructure during gas-tungsten- arc welding (GTAW) solidification process may be a supporting factor for technology optimization. The solidification theories and models developed for rapid solidification processes have improved considerably over the last decade, and increasing computer power allows direct simulations of the grains nucleation and growth in the molten zone for non-isothermal welding temperature conditions. A modified model has been developed on welding microstructure of GTAW. Using physically based welding metallurgical theory, the welding solidification process is simulated using 2-dimension cellular automaton (CA) method coupled with finite difference (FD) calculation of thermal and solute diffusions. The key problem of combination between CA and FD method are solidification latent heat and solid/liquid (S/L) interface solute partitioning. The temperature gradient, solidification velocity, undercooling and solute concentration are considered, and these factors determinated welding solidification microstructure morphology. It is found that the simulation can reproduce the CET of weld solidification process by reflecting the effect of a nucleating agent. The results are discussed in connection with theoretical prediction on CET and confirm the rationality of the theories. The possibilities of using numerical algorithms for; generation of microstructure formation during weld solidification are demonstrated. Moreover, the simulation microstructure agreed well with the experiment results.
GTAW Solidification Microstructure Cellular Automaton Finite difference Columnar-to-equiaxed
Xiaohu DENG Liwen ZHANG Jibin PEI Delun GUO
The State Key Laboratory for Materials Modification by Laser, Ion and Electron Beams, Dalian Univers Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China
国际会议
大连
英文
303-310
2007-08-19（万方平台首次上网日期，不代表论文的发表时间）