Effect of bainite volume fraction on mechanical properties of a ferrite-bainite-martensite steel

Abstract

Nowadays, triple phase ferrite-bainite-martensite steels have found widespread applications in automotive industry. The volume fraction of different phases is the key factor in determining mechanical properties of these steels. This paper investigates the effect of bainite volume fraction on microstructure and mechanical properties of a triple phase steel. Hence, an intercritical annealing treatment at 780 • C was followed by austempering treatment at 400 • C for different times. Microstructures were analysed using optical and scanning electron microscopy, and mechanical properties were also investigated by a tensile test. The results showed that the kinetics of austempering treatment had a good adaptation with JMAK equation. It was also found that increment of bainite phase from 0 to 42 vol.% decreased ultimate tensile strength from 952 to 578 MPa, but from 5.7 to 12 vol.% ductility increased. Results also showed that triple phase steels with 14.9 and 24.5 vol.% bainite demonstrated three-stage work hardening behaviour while other samples obeyed two-stage work hardening mechanism. K e y w o r d s : austempering treatment, triple phase steel, work hardening behaviour, mechanical properties

Comparative study on the effect of (Cr, Mo, V)-alloying on transformation and mechanical behavior of 0.2 wt.% C TRIP-assisted steel

“…Ductile austenite improves the steel ability for strain flow, while SIMT contributes to work hardening and ductility (the latter is due to delaying the neck formation [16]). Also, TRIP-effect is considered as a stress relaxation mechanism inhibiting the crack nucleation and propagation [17,18]. Summing up, TRIP-effect is an effective approach to increase strength/ductility complex that is beneficial for steels behavior under its processing and exploitation.…”

“…The multiphase state of TRIP-assisted steels can be acquired by using different approaches. The main ones are bainitizing processing [18,19] and Q&Ptreatment [20,21]. Bainitizing aims at "austenite → bainite" transformation to get the microstructure of low bainite or carbide-free nanostructured bainite (which is essentially the nanosized ferritic laths and film-like retained austenite) [22,23].…”

Corrosion inhibition of ferrite bainite AISI1040 steel in H2SO4 using biopolymer

“…Although a lot of research articles have come out concerning the excellent blend of mechanical properties in DP steels (A. Karimi, S. Kheirandish, 2017;Basantia et al, 2021;Bilal et al, 2019;Fereiduni & Ghasemi Banadkouki, 2014;Kumar et al, 2019;Shahzad et al, 2018;Xiong et al, 2019;Zhao et al, 2019;Zhu, 2019), further examinations are important to discover the influence of phase constituents on the corrosion resistance properties (Bignozzi et al, 2020;Gürkan Aydın, 2019;Ma et al, 2020;P. R. Prabhu, Prabhu, Sharma et al, 2020;Zhang et al, 2020).…”

Mechanical properties of carbide-free lower bainite in complex-alloyed constructional steel: Effect of bainitizing treatment parameters

“…Preventing cementite precipitation eventually results in austenite enrichment with carbon leading to increase in RA volume fraction [13]. Nanoscaled ferritic laths impart higher strength (reaching 2000-2400 MPa), while the absence of cementite carbides and the presence of retained austenite films provide the increased ductility (elongation of 10 % or higher) and impact toughness [5,14,15]. Moreover retained austenite may significantly contribute to mechanical properties due to TRIP-effect [16].…”