Effect of Al Content on the Microstructure and Mechanical Properties of the Sintered Fe–Mn–Al Porous Steel

Abstract

Al content is of great importance for the evolution of the microstructure and compressive performance of the high‐Mn and high‐Al porous steels. Herein, Fe–Mn–Al porous steels with different Al contents are prepared via powder sintering at different temperatures. The results show that the main phases of the sintered samples at 640 °C are α‐Fe, α‐Mn, and Al, while a small amount of Fe2Al5 and Al8Mn5 exists in the samples with 15 and 20 wt% Al. At 1200 °C, the sintered sample with 5 wt% Al is composed of γ‐Fe, while those with 15 and 20 wt% Al are mainly α‐Fe. The length of Mn depletion region and porosity of the samples increase with the increase of Al content. The largest total and open porosity are observed in the 1200 °C‐sintered sample with 20 wt% Al, which are 63.1 and 60.7 vol%, respectively. The compressive strength decreases sharply from 770 MPa for the sample with 5 wt% Al to 7.5 MPa with 15 wt% Al, after sintering at 1200 °C. Ductile fracture occurs in the sample with 5 wt% Al, while brittle fracture is the main fracture mode in those with 15 and 20 wt% Al.