Effects of annealing temperature and V addition on microstructure and mechanical properties of Fe-Mn-Al-C austenitic low-density steel

This study investigated the effect of annealing temperature (Ta=800-1000 & DEG;C) on the microstructure and me-chanical properties of Fe-25Mn-10Al-1.1 C-(0,0.48)V (wt%) austenitic low-density steels. The results show that Ta has significant influence on the microstructures of the two tested steels. Considerable amount of ferrites and x-carbides appeared on grain boundaries due to precipitation reaction (y+a + x) when annealed at a lower temperature of 800 & DEG;C, and the V addition would promote the precipitation reaction and cause an increase of ferrite content when annealed at no more than 900 & DEG;C. The content of VC reached a maximum at Ta= 900 & DEG;C, which also significantly inhibited the formation of x-carbide and delayed the recrystallization besides grain refinement for the V-added steel. Moreover, VC also inhibited the development of the E3n (n =1,2,3) boundaries at Ta of no more than 900 & DEG;C. Ultra-high yield strength of 1120 MPa was obtained when the V-added steel was annealed at 900 & DEG;C mainly due to the drastic VC precipitation. The present work provides a promising strategy to enhance the yield strength of austenitic low-density steel via tailoring Ta and the addition of V.

Automated summary

This study investigated the effect of annealing temperature on the microstructure and mechanical properties of Fe-25Mn-10Al-1.1C-(0,0.48)V austenitic low-density steels. The results showed that annealing temperature had a significant influence on the microstructures of the steels. The addition of V promoted the precipitation reaction and increased the ferrite content. VC inhibited the formation of x-carbide and delayed the recrystallization, leading to ultra-high yield strength of the V-added steel when annealed at 900℃. This study provides a promising strategy to enhance the yield strength of austenitic low-density steel by tailoring annealing temperature and adding V.