Strain Rate Dependence of Hot Tensile Behavior, Microstructure Evolution, and Fracture Mechanism of Lean Duplex Stainless Steel 2101

Abstract

Lean duplex stainless steel 2101 (LDX 2101) shows a good comprehensive performance of local corrosion resistance, stress corrosion cracking resistance, and high strength. [1][2][3][4] Compared with conventional duplex stainless steels (DSSs), LDX 2101, which uses cheap Mn and N to replace expensive Ni, is considered a potential candidate for cost efficiency and is widely used as a material in the nuclear, chemical, and food industries. [5] However, compared with other single-phase stainless steels, the hot deformation behavior of LDX 2101 is more complex, which makes it difficult to hot work and significantly hinders its large-scale industrial application. The edge cracking is a long-term problem during the hot deformation process of DSSs, especially for LDX 2101. [3,[6][7][8][9][10] The edge cracking of LDX 2101 under hot deformation conditions has not been completely solved. To avoid hot cracking of steel, several process parameters, such as deformation temperature and strain rate, must be considered. [11,12] Improper process parameters will affect the surface quality of the final product. It is generally believed that strain rate is an important factor affecting the thermal deformation behavior of DSSs. The effect of strain rate on the hot deformation behavior of these DSSs has been investigated by many research groups. Most of these studies have focused on the hot compression process of DSSs, when the material is subjected to compressive stress. Patra et al. observed the microstructure evolution of LDX 2101 during hot compression at 800À1000 C and studied its effect on hot working properties. [1] Kingklang et al. conducted hot compression tests on 2507 DSS at different temperatures and strain rates and proposed a flow stress model that could be used to design and optimize the DSS manufacturing process at high temperatures. [13] Fang et al. observed that cracks formed at the α/γ interface during the hot compression test of LDX 2101 and gradually propagated into the ferrite matrix. [3] Ha et al. studied the high-temperature deformation of (C þ N)-added S32101 DSS by hot compression. The results show that the hot deformation cracking originates from the precipitated phase at the ferriteÀaustenite interphase boundary. [14] Cizek et al. studied the microstructure evolution and softening mechanism of austenite and ferrite in 21CrÀ10NiÀ3Mo DSS by hot compression. A large part of the dynamic softening of austenite is attributed to discontinuous dynamic recrystallization (DDRX), and the softening mechanism within the ferrite is classified as continuous dynamic recrystallization (CDRX). [15] Mozumder et al. studies the compressive deformation behavior of FeÀMnÀAlÀNiÀC lightweight steel within a temperature regime of 1223À1423 K and at a strain rate of 10 s À1 . The results show that the face-centered cubic (FCC) phase recrystallizes by DDRX and the body-centered cubic (BCC) phase exhibits a DDRX-like mechanism near the FCC/BCC interphase boundaries. [16] Haghdadi et al. investigated the relationship between the ferrite...