Simulation Of Grain Growth In The HAZ Of Industrial Pure Aluminum

Both average grain size and grain size distribution in HAZ are the dominant micro structural features of weldment. Such features may govern many properties of the weldment, such as strength, ductility, toughness, corrosion resistance and so forth. Accordingly, prediction of the final grain size and grain distribution is crucial to a welding engineer. The nature of grain growth in the weldment is known to be stochastic. Therefore , using a stochastic method to predict the final grain size of weldment should be considered.Under the background of C++Buider, the grain growth process and kinetics of industrial pure aluminum(L1060) were simulated on the basis of the Monte Carlo (MC) method. The temperature field in welding HAZ was studied and analyzed. Welding heat curve was set up by argon-shielded tungsten arc welding experiment. The simulated welding heat cycle curve was compared with the real welding heat curve. The welding heat cycle curve which was near to the practice was available by non-lined quasi analog. Parameters of The index of grain growth and activation energy were determined by regression analysis. Grain size and distribution were predicted, and then kinetic process of grain growth and topology changes of material microstructure was simulated by MC method. The relations between average grain size and Monte Carlo step were established, and the growth process was made as flash animation, and the result of simulation has agreement with experiment result, which fits to the kinetics process of grain growth.On the basis of single grain growth simulation, the kinetic model of grain growth in welding HAZ was established by parameters of welding process , regression analysis and inducting welding heat cycle curve. Using visual interface of C++ Buider as run desk and using object-orientation, all kinds of functions were founded in system,grain structure of welding HAZ, evolvement of grain growth and distribution of grain size were simulated more correctly than else. Every functions of actor were founded in this system, and class which system needed was defined according to functions. The influence of heat pining was successfully simulated because of the temperature gradient in welding HAZ of industrial pure aluminum(L1060) ,the phenomenon of grain growth was simulated under different heat inputs , top temperature ,holding time and simulation results are consistent with experiment. There is a close relation between grain size and parameters in welding HAZ: the lager temperature gradient in HAZ , the more distance to line of fusion, the more little heat input and the big parameter of heat pining, the smaller grain size is in coarse grain of welding HAZ .