Diffuse Interface Field Variable Models Simulation Of Grain Growth In Welding Heat Affected Zones

Grain size is important performance indicators of metal materials. The crystal grain size directly affects material plasticity, resilience, strength, extensional, corrosive resistant, etc. Heat effect is inevitable in the Welding process, often causing welding heat affected zones (HAZ) to the crystal grain rough as a whole welding joints, which makes it the weakest link performance. Therefore, predictions of the HAZ ultimate crystal grain size distribution and crystal grain size distribution plays a key role for the quality control of welding joints. The paper took advantage of the diffuse interface model to simulation study of crystal grain grown up process in the welding HAZ of industrial pure aluminum(1060).The validity of the diffuse interface was preliminary proved through the simulation of small circle crystal grain contraction process in the infinity matrix. Then, with the variable model of diffuse interface field, dynamics process of normal crystal grain growing of industrial pure aluminum was simulated. The result of crystal grain grown up index was 0.49, which is very close to theoretical index.With the tungsten electrode argon-arc welding test, industrial pure aluminum: welding heat cycle curve was established. And contrasting the actual welding thermal cycle curve with the simulation of welding thermal cycle curve, using the origin software to do nonlinear fit, and the result got the simulation welding heat cycle curve which is close to the actual cycle curve. It was for welding heat affected zone crystal grain to lay a foundation. Through welding heat simulation tests, measuring the crystal grain size at the different temperature and in the different keeping temperature conditions. Using regression analysis to get the relation of crystal grain size and keeping temperature time, and establishing dynamics formula of crystal grain growing up in a welding HAZ. And comparing the result with welding test, certificating temperature gradient to "thermal nails Norte " action of crystal grain growing up, and the coefficient of thermal nails Norte is between 0.79-0.96. Amending dynamics formula of industrial pure aluminum crystal grain growing up in the welding heat...