Microstructure, Mechanical, and Wear Properties of Al-Alloyed Austempered Ductile Irons

Abstract

Spheroidal graphite cast irons with 0–4 wt% aluminum addition fabricated by green sand casting were austenitized at 900 °C for 90 min and subsequently austempered at 300 °C for 60 min. The samples were subjected to dry sliding wear tests against Al₂O₃ balls under various conditions. Microstructural analysis showed that increasing Al decreased the acicular ferrite ratio and disrupted graphite nodularity. Accordingly, ultimate tensile strength (UTS) and hardness decreased while impact strength increased except for the 4 wt% Al-alloyed cast iron. The Al₂O₃ layer formed around graphite nodules could not be removed during the austempering and caused an increase in the mechanical strength of this sample. Sliding tests revealed that the wear resistance of the samples increased with sliding speed and decreased with applied load. Worn surfaces predominantly suffered from abrasion, adhesion, and delamination. Although lower Al addition increased wear losses, 4 wt% Al-alloyed cast iron showed the best wear resistance.

Keywords:

• Ductile iron
• austempering
• aluminum alloying
• characterization

Acknowledgement

The author expresses his gratitude to Acelya Sandikoglu for her help with the production of cast irons.

Competing interests

The author has no relevant financial or nonfinancial interests to disclose.

Data availability

The raw/processed data required to reproduce these findings cannot be shared at this time, as the data also form part of an ongoing study.

Additional information

Funding

The author declares that no funds, grants, or other support were received during the preparation of this manuscript.