A mechanism of pick-up formation on 6063 aluminum alloy extrusions.

Effects of extrusion speed and compounds on surface defects in extruded-AA7003 alloy

“…This result is also corresponding to the results reported by Peason et al; when the Fe content increases in AA6063 alloy, they exhibit surface deterioration [17]. Meanwhile, Minoda et al proposed a similar but slightly different mechanism of the defect formation in the AA6063 alloy [18]: they thought that β-AlFeSi and Mg 2 Si compounds play a crucial role in the formation of the surface defects when the extrusion speed is increased. However, these mechanisms do not take into account the effect of the mechanical properties of the extrudates on the defect formation.…”

“…Since the number of pick-up is higher in the high-speed sample [17], these phenomena could be enhanced in the sample extruded at 20 m min −1 due to much higher processing heat. Although we detect both Al 9 (Mn,Fe) 2 Si and Mg 2 Si compounds within the pick-up as reported by Minoda et al (Figure 10), it seems that it is not essential for the formation of pick-up in the case of AA7003 alloy [18]. However, the appearance of pick-up without 'deposits' at the end may be related to the existence of Mg 2 Si and a peritectic reaction [18].…”

“…Although we detect both Al 9 (Mn,Fe) 2 Si and Mg 2 Si compounds within the pick-up as reported by Minoda et al (Figure 10), it seems that it is not essential for the formation of pick-up in the case of AA7003 alloy [18]. However, the appearance of pick-up without 'deposits' at the end may be related to the existence of Mg 2 Si and a peritectic reaction [18]. It is also confirmed that the distribution of fine Fe-rich particles whose smallest diameter is ≈ 1.5 μm is often observed when EDX maps using SEM are acquired from only the surface regions.…”

Corrosion issues of powder coated AA6060 aluminium profiles

“…The other one is due to a probable melting of the Mg 2 Si phase at 585°C. Minoda et al [4] has reported in their studies on AA6063 that pick-up defects occurred due to the peritectic reaction of Al, Mg 2 Si and b-AlFeSi at 576°C. As described, there are number of postulates exists in literature regarding pick up formation mechanism.…”

“…Such defects are usually classified as die lines and die pick-ups [2]. However, many researchers have reported different mechanisms for the pick-up formation [3,4]. Merk et al reports that during the extrusion process, an aluminium coating is developed on the die bearing surface which may cause die pickup formation.…”