Phase field simulation method for predicting nano alpha twin crystal precipitation and microscopic structure evolution in titanium alloy in local stress state

Abstract

The invention relates to the field of metallurgical casting, in particular to a phase field simulation method for predicting nano alpha twin crystal precipitation and microscopic structure evolution in titanium alloy in a local stress state, which comprises the following steps: S1, acquiring information such as Gibbs free energy density and interface energy of two phases and phase change strain tensors of different alpha variants in a beta-to-alpha solid phase change process of the titanium alloy; s2, establishing a phase field kinetic model, and solving a phase field control equation to obtain a sequence parameter result value; s3, in the phase transformation process under a certain supercooling degree, changing the stress load orientation and size, and obtaining different microstructure morphology information; and s4, performing visualization processing on corresponding microstructure evolution results under different input conditions, and clarifying an influence rule of a local stress state on a nano alpha twin crystal nucleation and evolution process. According to the method, the beta-to-alpha conversion process in the titanium alloy can be reproduced, and a visual prediction method is provided for the microstructure form and the evolution process of the titanium alloy under the thermal-mechanical coupling effect.

Description

technical field [0001] The invention relates to the field of metallurgical casting, and relates to a phase field simulation method for predicting the precipitation of nano-alpha twins and the evolution of microstructure in a titanium alloy under a local stress state. Background technique [0002] As a traditional engineering alloy, titanium alloy has the advantages of low density, high strength, high temperature resistance and corrosion resistance, and is widely used in aerospace, navigation and medical fields. The various microstructures of titanium alloys are mainly derived from the thermal-mechanical processing of its deformation and phase transformation coupling. The β→α transformation under high-temperature deformation is the key to the formation of the microstructure of titanium alloys. The formation of the microstructure is often affected by external forces and residual stress after hot working, which has a selective effect on the precipitation of α-phase transformati...

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Problems solved by technology

The strong texture even causes the appearance of "macro area", which significantly reduces the fatigue and creep properties of the alloy

However, it is difficult to characterize complex local stress states only relying on experimental methods

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