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23 pages, 14275 KiB

Open AccessArticle

FEM Simulation of Surface Micro-Groove Structure Fins Produced by Cryogenic-Temperature Extrusion Machining

by Xiaolong Yin, Zhilin Wang, Runyu Guo, Wan Wang, Hechun Yu and Hanbin Wang

Processes 2023, 11(2), 560; https://doi.org/10.3390/pr11020560 - 11 Feb 2023

Cited by 1 | Viewed by 1834

In the process of metal cutting, a large amount of chips that are difficult to reuse will be produced, resulting in resource waste. As a novel metal forming process, cryogenic-temperature extrusion machining (CT-EM) can directly process chips into usable fins with a surface micro-groove structure, which has the advantage of high efficiency, energy saving and flexibility. In this study, the effects of four parameters (compression ratio λ, rake angle of the tool α, friction coefficient μ and the constraining tool corner radius R) on the effective stress, temperature and formability of micro-groove fins produced by CT-EM and room-temperature extrusion machining (RT-EM) are investigated. The results show that the maximum effective stress and formability of CT-EM are larger than that of RT-EM, which indicates that CT-EM has greater advantages in the preparation of micro-groove fins. At a λ of 0.7, the formability of CT-EM is the best. Reducing the λ and α, or increasing the μ, can improve the forming effect of the fins. CT-EM can produce micro-groove fins with the best formability when λ = 0.7, α = 5°, μ = 0.75 and R = 0.1 mm. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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12 pages, 3756 KiB

Open AccessArticle

Effects of Machining Velocity on Ultra-Fine Grained Al 7075 Alloy Produced by Cryogenic Temperature Large Strain Extrusion Machining

by Xiaolong Yin, Haitao Chen and Wenjun Deng

Materials 2019, 12(10), 1656; https://doi.org/10.3390/ma12101656 - 21 May 2019

Cited by 12 | Viewed by 3285

Abstract

In this study, cryogenic temperature large strain extrusion machining (CT-LSEM) as a novel severe plastic deformation (SPD) method for producing ultra-fine grained (UFG) microstructure is investigated. Solution treated Al 7075 alloy was subjected to CT-LSEM, room temperature (RT) LSEM, as well as CT free machining (CT-FM) with different machining velocities to study their comparative effects. The microstructure evolution and mechanical properties were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Vickers hardness measurements. It is observed that the hardness of the sample has increased from 105 HV to 169 HV and the chip can be fully extruded under CT-LSEM at the velocity of 5.4 m/min. The chip thickness and hardness decrease with velocity except for RT-LSEM at the machining velocity of 21.6 m/min, under which the precipitation hardening exceeds the softening effect. The constraining tool and processing temperature play a significant role in chip morphology. DSC analysis suggests that the LSEM process can accelerate the aging kinetics of the alloy. A higher dislocation density, which is due to the suppression of dynamic recovery, contributes to the CT-LSEM samples, resulting in greater hardness than the RT-LSEM samples. Full article

(This article belongs to the Special Issue Materials by Non-traditional Methods of Severe Plastic Deformation (Spd))

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