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论文类型：期刊论文

发表时间：2019-01-01

发表刊物：HIGH TEMPERATURE MATERIALS AND PROCESSES

收录刊物：SCIE、EI

卷号：38

期号：1

页面范围：485-497

ISSN号：0334-6455

关键字：friction stir welding; Monte Carlo method; duplex alloy; recrystallization; acicular grain

摘要：A fully coupled thermo-mechanical model is established to simulate the temperature variations and the material deformations in friction stir welding (FSW) of Ti-6Al-4V. The extracted data are used for further simulation on microstructural evolutions. A multi scale model, which consists of the grain growth model in grain cluster scale and the phase transformation model in one grain scale, is proposed. The nuclei of alpha and beta phases, the recrystallizations and the grain growths are systematically investigated. Comparisons with experimental data and experimental observations can validate the newly proposed microstructural evolution model for Ti-6Al-4V. Results indicate that the volume fractions of alpha and beta phases can be directly determined by the cooling rates in FSW process. With the increase of the rotating speed, the volume fraction of alpha phase is increased and beta phase decreased due to the increase of welding temperature. With the decrease of the translational speed, the volume fraction of alpha phase gets bigger and beta phase smaller. The acicular alpha grain can be generated on the beta grain boundaries and grows along <1 1 0> direction on beta substrate. The average length of alpha grain can be increased with longer cooling time and decreased with lower rotating speed or higher translational speed.