An experimental investigation of mechanical properties of aluminium alloy products produced different extrusion conditions

With the extrusion process, profiles having whether solid or hollow sections can be producedeconomically. In the producing of hollow profiles seam welds occur evidently, for both solidand hollow profiles, transverse weld occur on the cross section; due to extruding billetsrepeatedly. Mainly transverse welds are cut on discarded as they have low strength and theyare near to die standing trace.In this study, it is aimed to investigate the structure and strength of seam weld, transverseweld and normal sections without weld comparatively. To achieve this, it is studied on anextrusion profile type which has seam weld, transverse weld regions and normal regionswithout weld. Also this profile has a geometry, which is suitable mechanical andmetallographic tests specimens from regions mentioned above in both extrusion direction, andproportional to extrusion direction.Producing extrusion profile has been performed by a press, which has a capacity of 1460tones, in a real producing coorporation and carried out by changing the exit temperature, andram speed, which are the important parameters. Exit temperature TÇ, is chosen as 440, 475,500, 520 and 560 oC. Extrusion velocity is also taken in the base of ram speed VR, andproduction is carried out at the speeds of 2, 4, 6, 10 and 15 mm/s. Therefore the effects ofextrusion parametres on mechanical properties have been investigated. Also macro, and microstructural investigations have been carried out on the specimens which have various billettemperatures, ram speeds and profile?s exit temperaturesIn order to do a detailed investigation the whole section is divided into nine regional parts totake specimens depending on features (seam welds and/or transverse welds, without welding- normal component) and directions (in the direction of extrusion, and proportional toextrusion direction) they have. Every specimens taken from each region have been appliedtensile, notch impact, and micro-hardness tests.It is seen clearly that some differences are occurred from the viewpoint of mechanical andstructural features between the regions, when the experimental results are investigated withoutregarding the extrusion parameters. But generally healing of mechanical properties of weldzones have occurred when exit temperatures increas with regarding extrusion parameters. Inaddition, it was observed commonly the structure of the material had a change through re-crystallization with increasing temperatures. This situation decreases the significance of seamweld regions. But insignificancy of seam weld region is designed as possible as can be fromthe viewpoint of whether mechanical properties or decorative. However when the ram speedincreases mechanical properties of normal-weldless regions, and transverse weld regions tendto increase while mechanical properties of seam weld tend to go decrease. In addition, it isclearly seen that the grain size is getting smaller with increasing ram speed as it is shown inmicro structural figures. However, when the macro structural figures have been investigatedas the ram speed increases more significance on seam welds occurs.This study shows that different occurrence mechanisms take place due to natural of extrusionmethod and process parameters variations in the neighborhood regions of the same extrusionproduction. They causes also variations on mechanical and structural features.Keywords: Aluminium extrusion, mechanical properties, seam weld, transverse weld