Influences of Cutting Speed and Material Mechanical Properties on Chip Deformation and Fracture during High-Speed Cutting of Inconel 718

Abstract

The paper aims to investigate the influences of material constitutive and fracture parameters in addition to cutting speed on chip formation during high-speed cutting of Inconel 718. Finite element analyses for chip formation are conducted with Johnson–Cook constitutive and fracture models. Meanwhile, experiments of high-speed orthogonal cutting are performed to verify the simulation results with cutting speeds ranging from 50 m/min to 7000 m/min. The research indicates that the chip morphology transforms from serrated to fragmented at the cutting speed of 7000 m/min due to embrittlement of the workpiece material under ultra-high cutting speeds. The parameter of shear localization sensitivity is put forward to describe the influences of material mechanical properties on serrated chip formation. The results demonstrate that the effects of initial yield stress and thermal softening coefficient on chip shear localization are much more remarkable than the other constitutive parameters. For the material fracture parameters, the effects of initial fracture strain and exponential factor of stress state on chip shear localization are more much prominent. This paper provides guidance for controlling chip formation through the adjustment of material mechanical properties and the selection of appropriate cutting parameters.

Investigation of Fracture Behavior and Mechanism in High-Speed Precise Shearing for Metal Bars with Prefabricated Fracture-Start Kerfs

“…where p ε  is the equivalent plastic strain rate; 1 ε , 2 ε , and 3 ε are the principal strain rates; dt is the time increment. The fracture process is defined by the Johnson-Cook cumulative damage model as expressed in Equation (5) [24], where D is the cumulative damage value, and fracture is allowed to occur when D ≥ 1.…”

“…The equivalent plastic strain is expressed as below [ 23 ], which is a measure of the degree of plastic deformation where is the equivalent plastic strain rate; , , and are the principal strain rates; dt is the time increment. The fracture process is defined by the Johnson–Cook cumulative damage model as expressed in Equation (5) [ 24 ], where D is the cumulative damage value, and fracture is allowed to occur when D ≥ 1. The equivalent fracture strain is dependent on stress triaxiality , equivalent plastic strain rate , and temperature ; is the increment of equivalent plastic strain.…”

Achieving the Minimum Roughness of Laser Milled Micro-Impressions on Ti 6Al 4V, Inconel 718, and Duralumin

“…Titanium alloy (Ti 6Al 4V), nickel alloy (Inconel 718), and aluminum alloy (AA 2024) are widely used materials in various engineering applications such as biomedical implants, aerospace, ship building, automotive, and many more as reported by Lupi et al [ 1 ], Nalli et al [ 2 ], and Wang et al [ 3 ]. The production of these materials in the form of near-net-shape products is extensively carried out through several means, especially selective laser melting (SLM) as adopted by Fan and Feng [ 4 ], and electron beam melting (EBM) used by Moiduddin et al [ 5 ].…”

Fractal Characteristics of Chip Morphology and Tool Wear in High-Speed Turning of Iron-Based Super Alloy

“…The formation of chips had a significant effect on the change of cutting temperature, cutting force and tool wear. It was crucial to reveal the influence law of the basic factors controlling the chip formation process [15]. In addition, the chip morphology had an important effect on the machined surface quality.…”