Initiation and Propagation of Plastic Yielding in Duplex Stainless Steel
- PDF / 5,517,781 Bytes
- 29 Pages / 593.972 x 792 pts Page_size
- 40 Downloads / 242 Views
ETALLIC alloys used in structural components commonly are polyphase and polycrystalline solids. The phases often exhibit contrasting values of stiffness and strength. The constituent crystals of the phases exhibit mechanical anisotropy stemming from their crystalline structures. These attributes of the material structure dictate that the mechanical response to loading is spatially heterogeneous at the scale of the phases and the crystals within the phases. One aspect of the mechanical response of great interest in the performance of a structural component is the intensity of the stress, and in particular, if it is sufficient to induce plastic deformation. The heterogeneity of the stress that develops as a consequence of a material’s microstructure complicates addressing this issue because of the complexity of interactions between phases and crystals as they react to imposed loads.
ANDREW C. POSHADEL and PAUL R. DAWSON are with the Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York. Contact e-mail: [email protected] MICHAEL A. GHARGHOURI is with the Canadian Nuclear Laboratories, Chalk River, ON, Canada. Manuscript submitted June 9, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
In this paper, the initiation and propagation of plastic yielding in a duplex stainless steel is examined in the context of its dual-phase, polycrystalline microstructure. For the loading, biaxial stress states range from uniaxial tension to balanced biaxial tension. Our interest is in quantifying the progression of yielding through the grain of a dual-phase, polycrystalline structural alloy in terms of parameters related to its mechanical properties. We focus on the combined effects of the stiffness (via the elastic moduli) and the strength (via the slip system critical resolved shear stresses). The paper builds on the findings of several previous papers that demonstrate that the stiffness and strength properties can be merged into a single parameter, referred to as the directional strength-to-stiffness parameter. This was shown initially for uniaxial stress states under monotonic loading conditions[1] and then extended to cyclic loading, again for uniaxial stress.[2] The materials studied in both of these cases were single-phase, polycrystalline, cubic alloys. With diffraction data from biaxial loading experiments on a single-phase alloy with cubic crystal structure,[3,4] the strength-to-stiffness parameter was shown to be an effective parameter for quantifying the progression of yielding under multiaxial stress conditions.[5] Based on digital image correlation data for the onset of slip in a titanium alloy, the strength-to-stiffness parameter was shown to correctly correlate with the onset of slip for the three dominant slip system families in the hexagonal close-packed phase.[6] Here, we employ
this metric for multiaxial strength-to-stiffness to rank crystals in terms of the relative order in which they will yield as the applied load increases in a dual-phase alloy subjected to different biaxial load
Data Loading...
