Mechanism of Saw Tooth-Shaped Chip Formation in Cast & Wrought High-Temperature Alloy GH4198

In order to reveal the formation mechanism of saw tooth-shaped chips in cast & wrought high-temperature alloy GH4198 and predict chip morphology through theoretical models, orthogonal cutting experiments were conducted. Based on the slip line field model, the geometric shape of the chips was predicted, and the influence of cutting parameters on chip formation was analyzed. A three-stage formation model of saw tooth-shaped chips considering the tool edge radius was proposed, and a two-dimension orthogonal cutting thermo-mechanical coupled finite element model was established, with its rationality being verified through experiments. By analyzing the variations of stress, equivalent plastic strain and temperature during the chip formation obtained from simulations, the formation mechanism of saw tooth-shaped chips was investigated. The results show that the shear angle increases with the increase in cutting speed and feed rate, while the chip thickness decreases with the increase in cutting speed. At the cutting speeds of 10, 20 and 30 m/min, the relative errors of the predicted chip thickness are respectively 4.20%, 12.34% and 24.73%, the maximum chip thickness compression ratios are respectively 3.19, 2.78 and 2.26, and the chip serration degrees are respectively 0.20, 0.36 and 0.58. At a cutting speed of 30 m/min, obvious cracks appear in the chips, and the saw teeth exhibit an overall inclined shape. At the feed rates of 0.05, 0.10 and 0.15 mm/r, the relative errors of the predicted minimum chip thickness are respectively 17.66%, 8.66% and 5.07%, the maximum chip thickness compression ratios are respectively 2.82, 2.78 and 2.61, and the chip serration degrees are respectively 0.12, 0.36 and 0.42. The slip line field model effectively predicts the variation of chip thickness with cutting parameters. With the increase in cutting speed and feed rate, the chip thickness compression ratio shows a decreasing trend, while the serration degree increases with a gradually slowing trend. Additionally, the influence of the tool edge radius on chip formation was analyzed through finite element simulation, and the effectiveness of the theoretical model for saw tooth-shaped chip formation was verified.