Case study: Enhancing induction heating processes with CENOS simulation software

In the world of heat-treatment methods, induction hardening stands out for its efficiency, reproducibility, and low distortion levels. However, when it comes to sintered steels, the process becomes more challenging due to their unique material properties. To overcome these challenges, a recent research study was conducted by an academic user who utilized the CENOS™ Induction Heating simulation software to gain a deeper understanding of the relationships between material and process parameters. This blog post will provide an overview of the project, highlight the benefits of simulation, and discuss the key findings.

The research project, “Development of a robust and reliable induction hardening process for components made of die-pressed sintered steel,” was funded by the non-profit Foundation Steel Application Research in Germany. The project was examined by an expert committee of the Research Association of the Association of the Iron and Metal Processing Industry. The simulations were performed with computing resources granted by RWTH Aachen University.

Induction heating of sintered steels poses challenges due to their low thermal conductivity, high residual stresses, reduced ductility, and high density of defects. To overcome these issues, a comprehensive understanding of the relationships between material properties and process parameters is crucial. Modeling and simulation play a vital role in optimizing induction heating processes for sintered steels.

The academic user employed CENOS™ Induction Heating simulation software to model the induction heating process and determine the thermal history of the 3D components. The software’s unique features, such as its ability to account for thermal-mechanical-metallurgical interactions, allowed the user to simulate the effects of phase transformation accurately. By utilizing a finite element model with a refined mesh density, the user could obtain reliable predictions of temperature profiles and phase transformation outcomes.

The project involved the examination of material properties, such as alloy composition, porosity, and carbon concentration, and their impact on the induction surface hardening process.

The study aimed to investigate the influence of material properties on the results of induction surface hardening. Two sintered steels were used in the study: Astaloy CrA and D11. Astaloy CrA is a pre-alloyed powder mixed with 2% nickel and 0.55% carbon, which provides good ductility and fatigue properties. D11 is a copper-alloyed steel that offers a cost-effective balance between ductility and hardenability.

Hollow cylindrical components were produced from both alloys using different pressure settings and variations in the carbon concentration in the D11 powder. This resulted in samples with varying porosity levels ranging from ε=9% to ε=15%. The samples were then sintered in a belt furnace at 1120°C under a N2+H2+CH4 atmosphere and rapidly cooled. The carbon concentration in the D11 samples was measured to be 0.45%C, 0.58%C, and 0.91%C, respectively.

Through experimental testing and simulation models, the user was able to establish relationships between these parameters and the resulting microstructure, hardness, residual stresses, and susceptibility to cracking. The results provided valuable insights into the characteristics of the material and process, enabling the identification of ideal material and process settings for induction hardened components.

The results of the study demonstrated the significant influence of material properties on induction surface hardening. The electrical conductivity and magnetic permeability of the materials were found to play crucial roles in determining the depth of the heated surface layer. Additionally, the study highlighted the correlations between thermal diffusivity, heat capacity, and the depth of the hardened surface layer. By understanding these relationships, researchers can optimize heat treatment processes and enhance the lifetime and reliability of mechanically loaded components.

The research project showcased the importance of modeling and simulation in optimizing induction heating processes for sintered steels. By investigating the impacts of material properties and process parameters, the study provided valuable insights into the electrical, magnetic, thermal, and mechanical characteristics of the materials. The findings can be applied to practical case studies, such as determining the best parameters for combining high tooth root bending strength and low crack susceptibility in sintered steel surface-hardened gears.

We invite readers to consider utilizing the CENOS™ Induction Heating simulation software for their own induction heating projects. With its advanced simulation capabilities and userfriendly interface, CENOS™ empowers researchers and engineers to optimize their processes, save time and resources, and achieve reliable results.