Lining of Metal Surface with Hard-Metal Foil using Shot Peening

Author:  Harada, Mori, Maki
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002028
Year of Publication:  2002
Authors Yasunori Harada, Ken-ichiro Mori and Seijiro Maki, Toyohashi University of Technology, Japan Introduction Light metals such as the aluminum and magnesium alloys are widely used for automotive components and electronic consumer products nowadays. Both alloys have a high ratio of strength to the weight and the low densities. Magnesium alloys have a good recyclable potential [1], but the application is still limited. Light metals, because they are not nearly as wear resistance as steel in ambient and high temperatures, are not commonly used in applications where wear resistance and strength are important. Therefore, there is strong demand to improve surface treatments that could guarantee the wear resistance of the parts in aggressive environments. For the improvement, the lining processes with hard metals such as steel and nickel are useful. The surface treatments are usually used to improve the surface properties such as wear resistance and corrosion resistance. Plating, PVD and CVD, are generally employed as the lining processes. The wear resistance of aluminum alloys was improved by dispersing the silicon-carbide particle to the surface [2] and by mixing PVD with ion implantation [3]. These lining processes, however, are inadequate for the use under severe conditions because of thin plating layers. Although a thick layer is formed by the termal splaying process [4], the loss of thermal splaying material becomes large [5]. For the purpose of improving the surface properties, the bonding processes in metal forming are very effective. If hard materials are bonded to the surface of light metals, the surface wear resistance will be improved. Two metals are bonded by applying large pressure and plastic deformation in rolling and extrusion processes [6]. The pressure and plastic deformation break up the oxide film and contaminants at the interface between the two metals, and new and clean surfaces suitable for the bonding are generated. In these processes, however, the bonding becomes difficult in the case of a large difference between flow stresses of two metals, because the deformation is concentrated at the metal with a small flow stress. The authors have proposed a lining process of metals with thin foils using shot peening [7]. In this method, the foil is bonded to the surface of the workpiece bringing about large plastic deformation and the pressure generated by the hit of many shots are utilized for the bonding. The lining process using shot peening is suitable for the bonding of thin and dissimilar foils required for the improvement of surface properties. By means of peening with many shots, the aluminum foil was successfully bonded over the surface of the carbon steel workpiece. In the present study, a method for lining light metals with hard materials using shot peening is proposed. The hard materials are bonded to the surface of light metal workpieces by the collision of many shots. The effects of shot speed and the processing temperature on the bondability were examined. To evaluate the wear resistance for the bonded surface of workpiece, wear test was also examined.

Download PDF