Einsatz von Si3N4-Keramik als Werkstoff für Walzwerkzeuge zum Warmwalzen von Draht

Translated title of the contribution: Application of Si3N4-ceramic as material for rolling tools for hot rolling of wire

Markus Lengauer

Research output: ThesisDoctoral Thesis

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Abstract

For hot-rolling wire rolling-tools made of cemented carbide are usually used. These tools are subjected to high thermally and mechanically caused wear and must therefore often be changed. Due to the outstanding characteristics of Si3N4, like high hardness, strength and wear-resistance, Si3N4 offers itself as a potential alternative to the cemented carbide. Thermal and mechanical stresses of a Si3N4-roll in the wire-stand DB03 in the multi-line rolling mill of Boehler Edelstahl in Kapfenberg were determined by means of the method of the finite elements. The temperatures in the rolling ring can reach up to 960 °C, the contact-induced tension stress when rolling high-strength nickel-based alloys up to 600 MPa. The rolling experiments confirm the results of the numeric computations. With a pair of ceramic rolls more than 1000 tons of wire-materials with a deformation resistance up to 340 MPa could be rolled. However, when processing a high-strength nickel-based alloy with a deformation resistance of 725 MPa fracturing of the rolls occurred after a few tons only. Based on the fractographic investigations and fracture-mechanical considerations, crack growth by cyclic fatigue could be determined as cause for the damage. Based on the test results also an estimation of the cyclic crack-growth parameters could be accomplished. Finally, an alternative lifetime-increasing modified clamping of the ceramic rolls was analysed theoretically.
Translated title of the contributionApplication of Si3N4-ceramic as material for rolling tools for hot rolling of wire
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Buchmayr, Bruno, Assessor B (internal)
  • Danzer, Robert, Assessor A (internal)
Publication statusPublished - 2007

Bibliographical note

embargoed until null

Keywords

  • Rolling
  • Silicon nitride
  • Contact stresses
  • Thermal stresses
  • Fracture

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