Issue 47

K. Hachellaf et alii, Frattura ed Integrità Strutturale, 47 (2019) 459-467; DOI: 10.3221/IGF-ESIS.47.36 460 materials. This process is well suited to alloys with a low melting point (aluminum, magnesium, copper) and found with these materials its main industrial applications: aeronautics, space, land transport, shipbuilding etc... During the welding operation the friction and the thermal field are factors that play an important role for the success of the FSW welding operation. The frictional heat of the shoulder of the tool and the heat of deformation of the tool spindle allow the material to soften without reaching the melting point. Significant plastic deformation and flow of this plasticized material occur as the tool is translated along the welding direction. The material is transported from the front to the rear edge of the tool, where it is forged to form a joint [1]. Panneerselvam and Lenin [1,2] observed that in the FSW of Nylon-6, a seal made with counter-clockwise rotation of the tool produced better material properties. Hoseinlaghab et al. [1,3] studied the creep properties of FSW-welded polyethylene plate assemblies and reported that under controlled conditions, the creep resistance of welds may be better than that of the base [1]. FSW can be used to join sheets and aluminum plates, without filler wire or shielding gas. Variety of materials ranging from aluminum alloys, copper, magnesium, lead, zinc and polymers and a material thickness ranging from 0.8 to 65 mm have been reported for successful welded joints at full penetration and without porosity and internal voids [4]. After the successful application of FSW on metals, Adeel et al. found that, depending on their physical and rheological properties, the welding parameters differ from polymer to polymer. Polymers with high melting temperature and viscosity require a higher speed of rotation and reach a sufficient heat and possibly a good resistance of the weld. In addition, to improve the welding force, the use of hot shoes or induction heating in situ showed good results [5]. Olivier L. has shown that temperature plays a key role in the success of welding and thus the understanding and control of the flow of the material are related to the temperature field and are critical for the success of FSW welding [6]. In other sense the improvement of mechanical properties such as fatigue, Zhou et al has confirmed through these tests on the service life is better in FSW (compared to other welding processes), higher service life for FSW welded joints (9 to 12 times higher) [7]. a) b) Figure 1 : FSW welding principle. a) FSW welding process, [8]. b) FSW welding tool, [9]. In this work we highlight the weldability of HDPE polymer by friction stir welding technique (FSW), the HDPE material is used in the drinking water networks and thus the city gas networks. Three welding parameters, the speed of rotation, the speed of advance and the geometrical shape of the tools, were studied. Mechanical behavior tests were carried out to evaluate and optimize the necessary parameters involved in achieving a good weld. E XPERIMENTAL PROCEDURE he material used is high density polyethylene (HDPE) is a thermoplastic polymer of high diffusion. It is part of the family of polyolefins, in the same way as low or medium density polyethylenes, used in the manufacture of pipes reserved for the supply and distribution of drinking water in accordance with Algerian standards NA7700-2 manufactured by the group CHIALI Sidi Bel-Abbes (Algeria), molar mass is of the order of 500 kg / mol and glass transition temperatures and melting are respectively (-125 ° C and 135 ° C) [10]. Tabs. 1 and 2 below show the mechanical and physical properties of HDPE (PE100). The tensile test carried out taken from a drinking water pipe made of HDPE (dumbbell type) in Fig. 2 according to the ISO 3167 standard [12]. Then perform the monotonic tensile operation to complete the main mechanical properties of a material (Fig. 3), such as yield strength, breaking strength and elongation. T