Tensile Fracture Modes in Fe-22Mn-0.6C and Fe-30Mn-3Si-3Al Twinning-Induced Plasticity (TWIP) Steels
- PDF / 1,520,204 Bytes
- 5 Pages / 593.972 x 792 pts Page_size
- 70 Downloads / 179 Views
induced plasticity (TWIP) steel possesses a unique combination of high tensile strength and uniform elongation,[1–5] making it a potential material for structural use. The TWIP effect was first proposed by Grassel et al.,[6] in Fe-Mn-Si-Al grade austenitic steel, later, Bouaziz and Guelton[7] reported that the effect also exists in Fe-Mn-C grade steel. Gutierrez-Urrutia and Raabe[8] and Idrissi et al.[9] proved that the interaction between deformation twins (DTs) and dislocations causes a remarkable improvement in the work-hardening capability of the steel and postpones the necking process. As the strain increases, the DTs divide the grains into finer domains and then reduce the mean free path of dislocation, exhibiting a dynamic Hall–Petch effect.[10,11] Although both FeMnC and FeMnSiAl TWIP steels have strong twinning capability and high
H.K. YANG, C.L. YANG, and Z.F. ZHANG are with the Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China, and also with the University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China. Contact e-mail: [email protected] Y.Z. TIAN, Z.J. ZHANG, and P. ZHANG are with the Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences. Manuscript submitted January 4, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS A
work-hardening rate during deformation, their alloying elements are quite different, and these solution elements may influence the inherent deformation mechanisms of the steels. An important influencing factor is the involvement of C-Mn atom couples,[12] which are the cause of the dynamic strain aging (DSA) phenomenon in FeMnC grade TWIP steel within particular strain rate and deformation temperature range.[13,14] The DSA effect results in visible serrations (or ‘‘jerky flow’’) in tensile stress–strain curves[12] and promotes the Portevin–le Chatelier (PLC) band, where localized strain occurs.[15,16] The interstitial carbon atoms, the DSA effect, and the PLC band are absent in the Fe-Mn-Si-Al grade TWIP steel.[17–19] Previous studies have found that the DSA effect results in the shear band and localized damage in aluminum alloys,[20–23] nickel alloys,[24] and austenitic stainless steel.[25] Although there are numerous studies on the DSA phenomenon and related PLC band observations,[15,16,26] the damage mechanisms of the DSA effect have rarely been reported in TWIP steel. To further reveal the different fracture mechanisms of TWIP steels, the fracture behavior of FeMnC (with the DSA effect) and FeMnSiAl (without the DSA effect) TWIP steels was investigated. This work will be helpful in understanding the different fracture behaviors of TWIP steels. In the present study, two ingots of Fe-22Mn-0.6C (wt pct, FeMnC) and Fe-30Mn-3Si-3Al (wt pct, FeMnSiAl) were melted in a vacuum induction furnace and austenitized at 1423 K (1150 °C) for 2 h to eliminate segregation. Next, they were hot-forged at 1123 K to 1423 K (850 °C to 1150 °C) into s
Data Loading...
