The recrystallization model and microstructure prediction of alloy 690 during hot deformation

• Hot compression simulation tests with various compression conditions and holding times are carried out for alloy 690.
• Microstructure prediction models including DRX, MDRX and grain growth for alloy 690 are established and validated.
• Combination of the model and FEM can provide theoretical guidance for microstructure optimization during hot deformation.

The recrystallization model and microstructure evolution during hot deformation of alloy 690 are investigated by the hot compression tests in a temperature range of 1000–1250 °C and at strain rates of 0.01–10 s− 1. A series of integrated microstructure prediction models for alloy 690 including dynamic recrystallization (DRX), meta-dynamic recrystallization (MDRX) and grain growth are developed in consideration of the actual requirement of hot deformation simulation. The accuracy of the models is validated using the finite element method (FEM) by comparing the simulation result with real manufactured one. Furthermore, the FORTRAN language is used to carry out secondary development of DEFORM-2D for the effectively invoking of the developed models in the hot extrusion simulation. The simulated microstructure agrees well with the microstructure of alloy 690 pipe obtained from the actual hot extrusion process in the factory, indicating the model developed in present study can be used for theoretical guidance in hot extrusion.

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