Open AccessMicrostructure and fracture mode of unalloyed dual-phase austempered ductile iron
Author(s) -
Petar Janjatović,
Cekic Eric Olivera,
Dragan Rajnović,
Sebastian Baloš,
K Vencislav Grabulov,
Leposava Šidjanin
Publication year - 2022
Publication title -
chemical industry and chemical engineering quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.189
H-Index - 26
eISSN - 2217-7434
pISSN - 1451-9372
DOI - 10.2298/ciceq201222027j
Subject(s) - microstructure , materials science , ferrite (magnet) , ductility (earth science) , austempering , ultimate tensile strength , scanning electron microscope , cleavage (geology) , metallurgy , composite material , fracture (geology) , optical microscope , dual phase steel , austenite , bainite , martensite , creep
Dual phase ADI material microstructure consists of different amounts and morphologies of ausferrite and free ferrite, obtained by subjecting ductile iron to specific heat treatment. As such, its strength is lower compared to comparable ADI materials, but exhibiting a higher ductility, the major disadvantage of ADI. In the current study, an unalloyed ductile iron was intercritical austenitised in two-phase regions (?+?) at four temperatures from 840 to 780?C for 2 hours and austempered at 400?C for 1 hour to obtain dual phase ADI with different percentages of free ferrite and ausferrite. Metallographic and fracture studies were performed by light and scanning electron microscopy, respectively. Microscopy results were correlated to tensile testing results. The results indicated that, as the amount of ausferrite present in the matrix increases, higher values of strength and lower ductility are obtained. The fracture surfaces of dual phase ADI microstructures with 22.8% of ausferrite in their matrix have regions of quasi-cleavage fracture around last-to-freeze zones, related to the presence of ausferrite in those areas. The specimens with the highest values of ausferrite of 86.8% among the dual phase microstructure have a dominant quasi-cleavage type of fracture.