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Zhang Q.,Jiangsu University | Xiao F.,Jiangsu University | Guo H.,Jiangsu University | Li C.,Jiangsu University | And 4 more authors.
Journal of Materials Processing Technology | Year: 2010

The present study has been undertaken in order to investigate the suitable lubricants and lubricating methods, which can be employed to form a magnesium alloy AZ31 sheet by warm negative incremental forming (NIF). For the intended purpose, Nano-K2Ti4O9 whisker and organic binder were employed to improve the bonding strength at lubrication coating/sheet interface and lubricating properties at elevated temperatures. The Nano-K2Ti4O9 whisker enhanced solid lubrication film and the solid graphite or MoS2 powder-coated porous ceramic coatings by pulsed anodic oxidation (PAO) almost have the same coefficient of the initial friction about 0.07-0.1 at room and elevated temperatures, which was satisfied with friction and lubrication condition of warm incremental forming (IF) of the metal sheet. Solid graphite or MoS2 powder-coated ceramic coatings possessed the remarkable lubrication and self-lubrication effect. These suggested lubricating methods gave an excellent solid lubrication performance and good surface quality of the formed parts in warm IF process of the metal sheet. © 2009 Elsevier B.V. All rights reserved.

Zhang Q.,Jiangsu University | Guo W.,Jiangsu University | Han Y.,Northeastern University China | Han W.,Baoji Boxin Metal Materials Ltd | And 2 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2013

The influence of surface roughness and compression ratio on the lateral surface microcracks of the compressed specimens of Ti-3Al-5Mo-4.5V titanium alloy (BT16) has been investigated by cold upsetting experiments, scanning electron microscopy (SEM) and optical microscopy (OM). The results show that the rolled and annealed α+β BT16 alloy bars with the finest equiaxed grains have the good cold upsetting performance. With the increasing of compression ratio and surface roughness, the lateral surface microcracks gradually increase. The lateral surface of the cold upsetting specimens and bolts is without macrocracks when the compression ratio reaches 75%, but under high magnification lateral surface microcracks can be distinctly observed, which are entirely different from common macrocracks. Surface quality of cold upsetting fasteners was evaluated and the relation between lateral surface roughness, microcracks and compression ratio was determined in cold upsetting test. Copyright © 2013, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.

Zhang Q.-L.,Jiangsu University | Xiao F.-G.,Jiangsu University | Guo H.-L.,Jiangsu University | Gao L.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2010

Flow stress of different temperature and deformation rate on AZ31B magnesium alloy sheets of different preparation method was studied by tensile test machine and metalloscope. The results show the basic characteristics of stress-strain curves of AZ31 magnesium alloy sheets prepared by extrusion, cross rolling, hot rolling and cold rolling is the same. Peak flow stress reduces with strain rate decreases and deformation temperature increases. There is obvious thickness effect on peak flow stress at low temperature; the peak flow stress is almost no alterative with the sheet thickness changes at the temperature higher than 350°C; the elongation of AZ31 magnesium alloy sheet is more than 45% at strain rate less than 1.0×10-2s -1 and deformation temperature higher than 150°C; anisotropy of longitudinal rolling sheet reduces with the temperature increases.

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