Inverse Determination of Johnson–Cook Parameters of Additively Produced Anisotropic Maraging Steel

Abstract

In powder bed-based additive manufacturing (AM), complex geometries can be produced in a layer-wise approach. Results of material science experiments regarding material property identification, e.g., tensile strength, show interdependencies between the test load direction and the layer orientation. This goes hand-in-hand with the measured cutting force, changing with the relative angle between cutting direction and layer orientation in orthogonal cutting tests. However, due to the specific process characteristics, the layer orientation results in anisotropic material properties. Therefore, during machining, the material behaves depending on the buildup direction, which influences the cutting process. To predict this behavior, a simplified inverse approach is developed to determine the buildup direction-dependent parameters of a modified Johnson–Cook model for cutting simulation. To qualify these cutting models, mainly the cutting force and additionally the chip formation examined during orthogonal cuts are used. In the present paper, the influence of the laser-powder-bed-fusion (LPBF) process parameters on subtractive post-processing are shown. A good agreement between verification experiments and simulations is achieved.

The Additive-Subtractive Process Chain - a Review

“…Results of the laser wire deposition process in terms of shape and roughness [158] The anisotropy of the material properties that arises in the AM process influences chip formation in post-processing [190][191][192]. The interdependencies of the layer orientation in PBF-LB additive manufacturing and the subsequent machining in terms of orthogonal cutting are investigated at the IfW intensively [192,193]. The analysis is based on systematically varied orientations of the test specimen during the layer-wise part generation that can be described by the orientation angles  and β (Fig.…”

“…16. Analysis of the influence of the cutting direction on chip formation and process characteristics [192] Fig. 17.…”

“…The aim of the simulation calculations is usually to predict the forces acting during the machining of a material, the temperature fields occurring and the resulting stresses in the component, in order to minimise, for example, displacement and vibrations of the tools and workpieces and to avoid damage to the component surface layers. A prerequisite for a realistic machining simulation is the availability of material models that represent the material behaviour under machining conditions sufficiently accurate [192]. Figure 22 shows an example for the identification of Johnson-Cook material model parameters for further use in cutting simulations [192].…”

“…A prerequisite for a realistic machining simulation is the availability of material models that represent the material behaviour under machining conditions sufficiently accurate [192]. Figure 22 shows an example for the identification of Johnson-Cook material model parameters for further use in cutting simulations [192]. [192] For additively manufactured materials, however, only few material models are available so far.…”

“…Figure 22 shows an example for the identification of Johnson-Cook material model parameters for further use in cutting simulations [192]. [192] For additively manufactured materials, however, only few material models are available so far. Consequently, very complex experimental parameter identifications are required if the machining of additively manufactured components is to be simulated.…”