Metal Processing Module

COMSOL Multiphysics® version 5.5 introduces the new Metal Processing Module. This add-on module allows you to model metallurgical phase transformations in materials like steel and cast iron.

Metal Processing Module Overview

The Metal Processing Module brings two new physics interfaces, Metal Phase Transformation and Austenite Decomposition for analyzing metallurgical phase transformations. Both of these interfaces provide functionality to model diffusive as well as displacive phase transformations. As with all COMSOL Multiphysics® add-on modules, the Metal Processing Module was developed with multiphysics in mind.

The module provides more sophisticated heat transfer functionality when combined with the Heat Transfer Module, with the ability to compute effective thermal material properties as well as phase transformation latent heat and the effects of heat radiation. Similarly, by combining it with the Structural Mechanics Module and its add-on modules, you can compute residual stresses, phase transformation strains, and deformations. The Metal Processing Module can also compute effective mechanical material properties and phenomena like transformation-induced plasticity (TRIP), and thermal strains can be included.

The Metal Phase Transformation Interface

The Metal Phase Transformation interface is used to study metallurgical phase transformations that occur in a material like steel, during heating or cooling, by computing the evolving phase composition in components like transmission gears, shafts, and axles during heat treatment. The Metallurgical phase feature is used to define the initial phase fraction and material properties, and the Phase transformation feature is used to define the source phase, destination phase, and phase transformation model. When the interface is added, two Metallurgical phase nodes and one Phase transformation node are automatically generated, as that is the minimum requirement to set up such a model. You can then define an arbitrary number of additional phases and phase transformations in your model.

Three types of phase transformation models are provided:

  • The Leblond–Devaux model
  • The Johnson–Mehl–Avrami–Kolmogorov (JMAK) model
  • The Koistinen–Marburger model

The first two models are suitable for diffusion–controlled phase transformations, such as when austenite decomposes into ferrite. The last model is suitable to model the displacive (diffusionless) martensitic phase transformation. In addition to these models, you can define your own phase transformation models.

The transformation of austenite to ferrite and pearlite is modeled in COMSOL Multiphysics using one of several phase transformation models.
The Metal Phase Transformation interface exemplified here to simulate phase transformations in a bar. The Settings window shows the Leblond–Devaux model for decomposition of austenite into a combination of ferrite and pearlite, which is shown in a section of the bar. All phase fractions over the radius of the bar are also shown at the 30-minute mark.

The Austenite Decomposition Interface

The Austenite Decomposition interface is based on the Metal Phase Transformation interface, but specialized to simulate the quenching of steels. As such, the Metallurgical Phase and Phase Transformation Model Builder tree nodes that represent the most common phase transformation processes during austenite decomposition are automatically generated when the interface is added. Using the Austenite Decomposition interface, you can compute how the phase composition evolves over time, at certain locations in a component, and compute the residual stress state after quenching.

The residual stresses from quenching are shown in a steel spur gear.
The Austenite Decomposition interface and its Settings window. Residual stresses are shown in a spur gear.

Calibration of Phase Transformation Models

Experimental calibration is required for a given phase transformation. Using the Metal Phase Transformation and Austenite Decompositon interfaces, you can compute common phase transformation diagrams to facilitate calibration against experimental data. A computed continuous cooling transformation (CCT) diagram is exemplified in the Transformation Diagram Computation model.

A computed CCT diagram showing temperature in metals over time.
Example of a computed continuous cooling transformation (CCT) diagram.

Multiphysics Functionality

The Metal Processing Module provides two multiphysics coupling nodes to facilitate coupling to the Heat Transfer in Solids and Solid Mechanics interfaces. The Phase Transformation Latent Heat multiphysics coupling is used to include heat released or absorbed during metallurgical phase transformations. The Phase Transformation Strain multiphysics coupling is used to include TRIP, plasticity of the individual metallurgical phases, and thermal strains. The multiphysics couplings can be used with both the Metal Phase Transformation and Austenite Decomposition interfaces. Additionally, the Metal Processing Module can be used together with the AC/DC Module to model induction hardening, and processes like carburization can be modeled as a general diffusion problem.

Example Tutorial Models

The Metal Processing Module includes four fully documented tutorial models to demonstrate the features and functionality available.

Transformation Diagram Computation

A computed CCT diagram.
This model shows how to compute transformation diagrams. The results show a computed CCT diagram.

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Phase Transformations in a Round Bar

A model showing the phase fraction of martensite at 1800 seconds.
This model shows how to simulate phase transformations in a round bar that is being cooled from an austenitized state. The results show the phase fraction of martensite.

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Quenching of a Steel Billet

A plot showing how metallurgical phase composition evolves over 600 seconds.
This model shows how to simulate oil quenching of a steel billet. The results show the phase composition of the various metallurgical phases evolving over time.

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Carburization and Quenching of a Steel Gear

A steel gear model visualizing the residual stresses from carburization and quenching.
This model shows how to simulate carburization and quenching of a steel gear. The results show the residual stresses in the gear.

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