The Experts below are selected from a list of 5808 Experts worldwide ranked by ideXlab platform
Xing Ai - One of the best experts on this subject based on the ideXlab platform.
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investigations of critical cutting speed and ductile to brittle Transition mechanism for workpiece material in ultra high speed machining
International Journal of Mechanical Sciences, 2015Co-Authors: Bing Wang, Guosheng Su, Qinghua Song, Xing AiAbstract:Abstract This paper investigates the brittle removal mechanism of ductile materials in ultra-high speed machining (UHSM). Firstly, a predictive model of critical cutting speed for UHSM is proposed with the theory of stress wave propagation. The predicted critical cutting speed for Ductile-to-Brittle Transition of ductile materials is then validated by machining experiments of 7050-T7451 aluminum alloy at the cutting speeds ranging from 50 m/min to 8000 m/min. The experimental results show that fragmented chips are produced above the critical cutting speed of 5000 m/min for 7050-T7451 aluminum alloy. The scanning electron microscopic (SEM) images of chips, chip roots and finished workpiece surfaces are observed and analyzed. Large amounts of brittle cracks and cleavage steps are observed on the fragmented chip surface obtained under the ultra-high cutting speed. Due to the remained brittle cracks, the finished surface quality obtained with UHSM is worse than that obtained with high speed machining. Secondly, the specific energy models for the chip formation are proposed and validated by experiments under ductile regime machining and brittle regime machining, respectively. The specific energies consumed for continuous and serrated chip formation mainly include plastic deformation energy located in the primary shear zone, the friction work between the tool–chip interface, and the chip kinetic energy. The plastic deformation energy accounts for the largest proportion among the total specific energy. Comparatively, the specific energy consumed during fragmented chip formation mainly includes the local kinetic energy of fragments and fracture surface energy. When the chip morphology evolves from serrated to fragmented one, the specific energy consumed reduces substantially, which demonstrates that the UHSM is beneficial for the energy saving. Lastly, taking both of the material removal efficiency and machined surface quality into consideration, the UHSM is recommended to be applied in rough machining or semi-finishing, while high speed machining is recommended to be applied in finishing process. This research firstly reveals the control mechanism for Ductile-to-Brittle Transition of ductile materials under critical cutting speed (i.e. critical strain rate) considering solid mechanics and metal cutting principles as well as energy consumption simultaneously. This paper is enticing from both engineering and analytical perspectives aimed at revealing the mechanism of UHSM and instructing the optimization of machining parameters.
Bing Wang - One of the best experts on this subject based on the ideXlab platform.
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investigations of critical cutting speed and ductile to brittle Transition mechanism for workpiece material in ultra high speed machining
International Journal of Mechanical Sciences, 2015Co-Authors: Bing Wang, Guosheng Su, Qinghua Song, Xing AiAbstract:Abstract This paper investigates the brittle removal mechanism of ductile materials in ultra-high speed machining (UHSM). Firstly, a predictive model of critical cutting speed for UHSM is proposed with the theory of stress wave propagation. The predicted critical cutting speed for Ductile-to-Brittle Transition of ductile materials is then validated by machining experiments of 7050-T7451 aluminum alloy at the cutting speeds ranging from 50 m/min to 8000 m/min. The experimental results show that fragmented chips are produced above the critical cutting speed of 5000 m/min for 7050-T7451 aluminum alloy. The scanning electron microscopic (SEM) images of chips, chip roots and finished workpiece surfaces are observed and analyzed. Large amounts of brittle cracks and cleavage steps are observed on the fragmented chip surface obtained under the ultra-high cutting speed. Due to the remained brittle cracks, the finished surface quality obtained with UHSM is worse than that obtained with high speed machining. Secondly, the specific energy models for the chip formation are proposed and validated by experiments under ductile regime machining and brittle regime machining, respectively. The specific energies consumed for continuous and serrated chip formation mainly include plastic deformation energy located in the primary shear zone, the friction work between the tool–chip interface, and the chip kinetic energy. The plastic deformation energy accounts for the largest proportion among the total specific energy. Comparatively, the specific energy consumed during fragmented chip formation mainly includes the local kinetic energy of fragments and fracture surface energy. When the chip morphology evolves from serrated to fragmented one, the specific energy consumed reduces substantially, which demonstrates that the UHSM is beneficial for the energy saving. Lastly, taking both of the material removal efficiency and machined surface quality into consideration, the UHSM is recommended to be applied in rough machining or semi-finishing, while high speed machining is recommended to be applied in finishing process. This research firstly reveals the control mechanism for Ductile-to-Brittle Transition of ductile materials under critical cutting speed (i.e. critical strain rate) considering solid mechanics and metal cutting principles as well as energy consumption simultaneously. This paper is enticing from both engineering and analytical perspectives aimed at revealing the mechanism of UHSM and instructing the optimization of machining parameters.
M Date - One of the best experts on this subject based on the ideXlab platform.
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ductile to brittle Transition in sn zn solder joints measured by impact test
Scripta Materialia, 2004Co-Authors: M Date, T Shoji, Masaru Fujiyoshi, Koji Sato, K N TuAbstract:Abstract Sn–9Zn and Sn–8Zn–3Bi solder balls were bonded to Cu or electroless Au/Ni(P) pads, and the effect of aging on impact reliability was investigated. A test similar to the classic Charpy impact test was performed to measure the impact toughness of the solder joints. In the case of the solder/Cu joints, γ-Cu5Zn8 at the bond interface thickened remarkably with the aging time, accompanied by void formation, resulting in a Ductile-to-Brittle Transition of the joint. In the case of the solder/Au/Ni(P) joints, however, the slow dissolution and diffusion of Ni into the solders as well as the redeposition of Zn at the interface contributed to maintaining high impact toughness even after a prolonged aging. All of the bumps on the Au/Ni(P) broke in a ductile manner.
Qinghua Song - One of the best experts on this subject based on the ideXlab platform.
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investigations of critical cutting speed and ductile to brittle Transition mechanism for workpiece material in ultra high speed machining
International Journal of Mechanical Sciences, 2015Co-Authors: Bing Wang, Guosheng Su, Qinghua Song, Xing AiAbstract:Abstract This paper investigates the brittle removal mechanism of ductile materials in ultra-high speed machining (UHSM). Firstly, a predictive model of critical cutting speed for UHSM is proposed with the theory of stress wave propagation. The predicted critical cutting speed for Ductile-to-Brittle Transition of ductile materials is then validated by machining experiments of 7050-T7451 aluminum alloy at the cutting speeds ranging from 50 m/min to 8000 m/min. The experimental results show that fragmented chips are produced above the critical cutting speed of 5000 m/min for 7050-T7451 aluminum alloy. The scanning electron microscopic (SEM) images of chips, chip roots and finished workpiece surfaces are observed and analyzed. Large amounts of brittle cracks and cleavage steps are observed on the fragmented chip surface obtained under the ultra-high cutting speed. Due to the remained brittle cracks, the finished surface quality obtained with UHSM is worse than that obtained with high speed machining. Secondly, the specific energy models for the chip formation are proposed and validated by experiments under ductile regime machining and brittle regime machining, respectively. The specific energies consumed for continuous and serrated chip formation mainly include plastic deformation energy located in the primary shear zone, the friction work between the tool–chip interface, and the chip kinetic energy. The plastic deformation energy accounts for the largest proportion among the total specific energy. Comparatively, the specific energy consumed during fragmented chip formation mainly includes the local kinetic energy of fragments and fracture surface energy. When the chip morphology evolves from serrated to fragmented one, the specific energy consumed reduces substantially, which demonstrates that the UHSM is beneficial for the energy saving. Lastly, taking both of the material removal efficiency and machined surface quality into consideration, the UHSM is recommended to be applied in rough machining or semi-finishing, while high speed machining is recommended to be applied in finishing process. This research firstly reveals the control mechanism for Ductile-to-Brittle Transition of ductile materials under critical cutting speed (i.e. critical strain rate) considering solid mechanics and metal cutting principles as well as energy consumption simultaneously. This paper is enticing from both engineering and analytical perspectives aimed at revealing the mechanism of UHSM and instructing the optimization of machining parameters.
K N Tu - One of the best experts on this subject based on the ideXlab platform.
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ductile to brittle Transition in sn zn solder joints measured by impact test
Scripta Materialia, 2004Co-Authors: M Date, T Shoji, Masaru Fujiyoshi, Koji Sato, K N TuAbstract:Abstract Sn–9Zn and Sn–8Zn–3Bi solder balls were bonded to Cu or electroless Au/Ni(P) pads, and the effect of aging on impact reliability was investigated. A test similar to the classic Charpy impact test was performed to measure the impact toughness of the solder joints. In the case of the solder/Cu joints, γ-Cu5Zn8 at the bond interface thickened remarkably with the aging time, accompanied by void formation, resulting in a Ductile-to-Brittle Transition of the joint. In the case of the solder/Au/Ni(P) joints, however, the slow dissolution and diffusion of Ni into the solders as well as the redeposition of Zn at the interface contributed to maintaining high impact toughness even after a prolonged aging. All of the bumps on the Au/Ni(P) broke in a ductile manner.
