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Chen L.,Guangdong University of Technology | Jie X.,Guangdong University of Technology | Zheng X.,Guangdong Greatoo Moulds Inc. | Li G.,Guangdong University of Technology
Advanced Materials Research | Year: 2011

35 steel was processed in order to investigate its structure and performance after strengthened shot peening and gas tufftriding process. The composition,structure and phase of the samples were analyzed by means of scanning electron micrograph(SEM),metallographic microscope and X-ray diffraction(XRD)respectively. The results show that the hardness of samples after strengthened shot peening increases by about 100 HV 0.025and the friction coefficient and corrosion rate decrease.However,the samples treated with gas tufftriding after strengthened shot peening exhibit the performance of approximate 3 times hardness of the original samples, lower friction coefficient,more excellent tribological characteristics,stronger corrosion-resistance with a stable and broad passivation region. © (2011) Trans Tech Publications, Switzerland.

Guangdong Greatoo Moulds Inc. | Date: 2010-03-30

Casting machines; Die-stamping machines; Electric knife sharpeners; Embossing machines; Engraving machines; Injection plastic molding machines; Machine parts, namely, molds for use in the manufacture of tires; Mechanical presses; Mechanical seals; Rolling mills; Rubber forming machines; Rubber mixing machines; Washing machines for household purposes.

Liu L.-L.,Guangdong University of Technology | Mai Y.-J.,Guangdong University of Technology | Jie X.-H.,Guangdong University of Technology | Yu N.,Guangdong Greatoo Moulds Inc. | Zheng X.-X.,Guangdong Greatoo Moulds Inc.
Mocaxue Xuebao/Tribology | Year: 2010

Nanocrystalline layers were fabricated on the surface of 45# steel by high pressure shot peening. Friction and wear tests of the nanocrystalline surface layer were implemented on a Model MMU-5G high temperature friction and wear tester. Microstructure of the surface layer was characterized by transmission electron microcopy (TEM). Differential scanning calorimetry (DSC) was employed to expatiate the thermal stability of the surface layer. Composition and morphology of the worn surfaces were also characterized by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Because the high hardness of the surface layer by the strengthening of fine grains and working hardening dramatically reduced the real area of contact, the wear resistance of shot peening sample was better than that of as-received sample at temperatures ranging from room temperature to 200°C. However, from 200°C to 400°C the as-received sample showed better tribological behavior that of the surface layer. It was because defects, e.g. grain boundary, dislocation, vacancy induced by the process of surface nanocrystallization were in favor of the diffusions of oxygen ions inwards and/or metal ions outwards and hence accelerated the formation and breakdown of the loose oxide scale. Friction and wear of untreated and treated samples were comparable from 400°C to 550°C because of the recovery and growth of grain of the nanocrystalline layer.

Wang R.,Guangdong University of Technology | Jie X.,Guangdong University of Technology | Zeng X.,Guangdong Greatoo Moulds Inc. | Huang Z.,Guangdong Greatoo Moulds Inc.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

In order to improve the anti adhesion performance of 35 steel surface, micro-nano structure was realized on the surface by using mechanical peening way, and micro-nano structure aluminize composite layer was formed by vacuum evaporation plating aluminum. The composite layer' 3D morphology was observated and analyzed by laser confocal microscope and SEM, its combination performance was studied by filing test and shock cooling and heating test, its adhesive force was measured by using WS-2005 coating adhesion automatic scratch machine, its composition and morphology after vulcanization was analysised by EDS and SEM. The results show that 35 steel surface is changed into micro-nano structure by using low blast pressure and small diameter of shot peening technology. The presence of large amounts of grain boundaries, dislocations, vacancy defects provide more diffusion channels for aluminum atoms, which make aluminum film and substrate bind tightly; The surface of aluminum layer self passivates into a dense aluminum film, which can prevent effectively chemical reaction between iron atoms and rubber sulfide. The micro-nano structured surface reduces its actual contact area effectively and decreases its adhesive force correspondly, which make the peening aluminize sample surface's sulfide adhesive capacity far less than that of the untreated sample.

Mai Y.-j.,Guangdong University of Technology | Jie X.-h.,Guangdong University of Technology | Liu L.-l.,Guangdong University of Technology | Yu N.,Guangdong Greatoo Moulds Inc. | Zheng X.-x.,Guangdong Greatoo Moulds Inc.
Applied Surface Science | Year: 2010

A nanocrystalline layer with ultrafine grains (about 30-40 nm) on the surface of 7050 aluminum alloy was fabricated by a new technique called High Pressure Shot Peening (HPSP) which is the combination of common Shot Peening equipment with a pressurizing vessel. Relationship between hot flow and temperature was observed by Differential Scanning Calorimetry (DSC) and the activation energy, calculated by Kisssinger equation, of the as-treated sample increased 26.6 kJ/mol when it is compared with the as-reserved sample. The Bragg peaks of the as-prepared samples, respectively treated with various annealing treatments were characterized by XRD and the microhardness distribution along the depth from the treated surface were measured at the same time, which indicated that the broadening of Bragg peaks decreased with the increasing of anneal temperature; the grain size, calculated by Scherrer-Wilson equation, increased obviously during 180-220 °C, accordingly, the microhardness obviously decreased. According to the results of DSC, XRD and microhardness, it is reasonable to deduce that the temperature range of thermal stability for aluminum alloy nanocrystalline layer is lower than 200 °C. © 2009 Elsevier B.V. All rights reserved.

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