Determination of Material Constitutive Laws for Inconel 718 Superalloy Under Different Strain Rates and Working Temperat
- PDF / 5,874,684 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 58 Downloads / 214 Views
JMEPEG DOI: 10.1007/s11665-017-3017-8
Determination of Material Constitutive Laws for Inconel 718 Superalloy Under Different Strain Rates and Working Temperatures W. Grzesik, P. Niesłony, and P. Laskowski (Submitted April 13, 2017; in revised form October 3, 2017) In this paper, a special procedure for the prediction of parameters of the Johnson–Cook constitutive material models is proposed based on the experimental data and specially developed MATLAB scripts which allow advanced modeling of complex 3D response surfaces. Experimental investigations concern two various strain rates of 1023 and 101 1/s and the testing temperature ranging from the ambient up to 700 °C. As a result, a set of mathematical equations which fit the experimental data is determined. The applicability of the experimentally derived constitutive models to the FEM modeling of real machining processes of Inconel 718 alloy is verified. Keywords
should be considered in the material constitutive models used in the modeling of machining process. This aspect is particularly important in the machining of nickel-based alloys which retain high strength at a high temperature of above 800 C. In order to consider the above-mentioned effects, some modifications of the J-C model are proposed, as follows:
constitutive model, machining, modeling
1. Introduction In modeling of the machining process and various machining operations using FEM technique, typically four material models including plastic, elastic–plastic, viscoplastic and elastic–viscoplastic material behavior are employed (Ref 1). In practice, more advanced constitutive material models which also consider strain hardening, thermal softening and microstructure changes as functions of three factors including strain, strain rate and temperature are applied. As a result, a number of different constitutive models which take into consideration these variable factors are used by FEM users (Ref 1-4). In this investigation, a classical Johnson–Cook model defined by Eq 1 is used. !! e_ p T To m n 1 req ¼ A þ Bep 1 þ C ln 0 Tt To e_ p ðEq 1Þ where ep is the equivalent strain; e_ p is the equivalent strain rate; e_ 0p is the reference strain rate; T is temperature; T0 is ambient temperature; Tt is melting temperature; A, B, C, n, m are material constants and exponents. The Johnson–Cook (J-C) model is the most frequently used material constitutive model for characterizing the material behavior in the primary and secondary shear zones. It should be noted that the J-C model given by Eq 1 describes accurately plastic deformation below fracture initiation (equivalently to the separation of mesh nodes). On the other hand, the material fracture in the chip formation zone and an intensive thermal effect
W. Grzesik and P. Niesłony, Opole University of Technology, Opole, Poland; and P. Laskowski, Pratt & Whitney, Rzeszow, Poland. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
• •
thermal softening (Ref 3, 4), thermal softening as a function of temperature (Re
Data Loading...
