Effects of microstructure and notches on the mechanical properties of dual-phase steels

Bayram A., Uguz A., Ula M.

Materials Characterization, vol.43, no.4, pp.259-269, 1999 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 4
  • Publication Date: 1999
  • Doi Number: 10.1016/s1044-5803(99)00044-3
  • Journal Name: Materials Characterization
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.259-269
  • Bursa Uludag University Affiliated: Yes


A low-carbon (0.1%) steel has been subjected to three different heat treatments to obtain dual-phase steels with different microstructures. The steel with the intercritically annealed microstructure of equiaxed ferrite-martensite exhibited the highest tensile strength, the lowest ductility, and intermediate fracture toughness properties. Step quenching also produced an equiaxed ferrite-martensite structure, but the material had the worst mechanical properties of the three different heat-treatment conditions. In contrast to the other two heat-treatment conditions, step annealing produced a fibrous (fine, needle-like) ferrite-plus-martensite structure. This gave rise to a material of intermediate tensile strength but with the highest ductility, notch strength, and fracture toughness. It is argued that optimum mechanical properties in a dual-phase steel can best be achieved by obtaining a microstructure containing fine, fibrous needle-like, martensite.