Modeling TRIP Steel Deformation with Abaqus UMAT

TRIP (Transformation-Induced Plasticity) steels are a class of advanced high-strength steels that exhibit favorable mechanical properties such as high strength, ductility, and toughness. This is due to the strain-induced martensitic transformation (SIMT) that occurs during plastic deformation.

Our company has developed a UMAT (User Material) FORTRAN subroutine for Abaqus based on the constitutive model proposed in the paper “Computational simulation of the dependence of the austenitic grain size on the deformation behavior of TRIP steels” by Iwamoto and Tsuta.

abaqus-trip-steels-umat-subroutne-banumusa-grain-size--600x317Key Features

1. Strain-Induced Martensitic Transformation (SIMT) Kinetics Model:

– The model considers the dependence of the SIMT on the austenitic grain size (AGS) using the Hall-Petch relationship.
– The rate of increase in the volume fraction of martensite is expressed as a function of the AGS, stress state, and strain rate.

2. Asymmetric Deformation Behavior:

– The constitutive equation incorporates the asymmetric behavior of austenite and martensite under tension and compression using a yield function that includes the third invariant of the deviatoric stress.
– This allows for accurate modeling of the deformation behavior of TRIP steels.

3. Finite Deformation Formulation:

– The constitutive model is generalized to account for finite deformation, ensuring the accuracy of the simulations for large-strain applications.

4. Validation:

– The developed UMAT subroutine has been validated against the computational results presented in the paper.
– The subroutine can accurately capture the dependence of the mechanical properties, such as the uniform elongation and tensile strength, on the AGS under different environmental temperatures.


– Modeling and simulation of the deformation behavior of TRIP steels in various manufacturing processes, such as forming and machining.
– Optimization of the mechanical properties of TRIP through the control of the AGS.
– Incorporation into larger-scale finite element models for the design and analysis of TRIP steel components.

Our UMAT FORTRAN subroutine provides a robust and efficient tool for the accurate modeling of TRIP steel behavior, enabling our customers to optimize the performance of their steel products and manufacturing processes.


If you like this subroutine, contact us.