Hardness Assessment Considering Nitrided Layers Based on Tempering Tests for Numerical Wear Prediction for Forging...

Area of Science:

• Materials Science
• Mechanical Engineering
• Tribology

Background:

• Nitriding is standard for forging tool wear reduction and surface hardening.
• Current wear models like Archard's fail to account for nitriding's microstructural and thermal-mechanical effects.
• Accurate wear prediction requires incorporating these complex surface modifications.

Purpose of the Study:

• To develop and validate a new material model for predicting hardness evolution in nitrided forging tools.
• To integrate this model into a numerical wear simulation for improved accuracy.
• To assess the model's predictive capability under forging conditions.

Main Methods:

• Development of two tempering tests to analyze hardness changes in H11 tool steel nitride profiles.
• Observation of tempering effects influenced by temperature, stress, and time.
• Implementation of a new material model into an existing finite element (FE) wear model.
• Validation through laboratory forging test series.

Main Results:

• Significant tempering effects on hardness were observed, dependent on test conditions.
• The new material model successfully predicted hardness development in nitrided tools, especially for high forging cycles.
• Adhesion effects emerged unexpectedly, limiting the overall applicability of the wear prediction.

Conclusions:

• Numerical prediction of hardness evolution due to tempering in nitrided forging tools is feasible.
• The developed model shows promise for enhancing wear simulations in high-cycle forging.
• Further research is needed to address adhesion phenomena for comprehensive wear prediction.