Microstructure Simulation Of Grain Growth In Heat Affected Zone Of Weldment

Average grain size and grain size distribution in HAZ is the dominant microstructural 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. Hence, using a deterministic method for predicting the final grain size of weldment should be reconsidered.Under the background of C++Buider, The grain growth process and kinetics of ultra-pure ferrite stainless steel (EB26-1) was simulated by using 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 practice 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 of grain size were predicted, and then kinetic process of grain growth and topology changes of material microstructure was simulated by MC method. The relation of average grain size and Monte Carlo step was established, and its growth process was made flash animation, and the result of simulation has agreement with experiment result, which fits to the kinetics process of grain growth.At the base of pure grain growth simulation, the kinetic model of grain growth in welding HAZ was established by parameters of weldinginprocess and regression analysis and inducting welding heat cycle curve. Using visual interface of C++ Buider as run deck and using object-orientation, all kinds of functions was found 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 found in this system, and class which system needed was defined according functions. The influence of heat pining was successfully simulated because of temperature gradient in welding HAZ of ultra-pure ferrite stainless steel (EB26-1), phenomenon of grain growth was simulated under the different heat input, top temperature and holding time and simulation results accorded with experiment. Aiming at simulated pictures of welding parameter, welding heat input, top temperature, heat pining and temperature gradient which affected grain growth of welding HAZ. There are close relation between grain size and parameters in welding HAZ: the lager temperature gradient in , the more distance to line of fusion, the more little heat input and the big parameter of heat pining, the smaller is ferrite grain size in coarse grain of welding HAZ .