Effect of High Rotational-Speed Friction-Stir Welding on Microstructure and Properties of Welded Joints of 6061-T6 Al Alloy Ultrathin Plate

Abstract

The butt joint of an Al alloy ultrathin plate with a thickness of 0.5 mm is realized by a high rotational-speed friction-stir welding process. It overcomes the welding difficulty that the ultrathin plate is often torn, and it cannot be formed by conventional friction-stir welding. The results show that the weld surface is well-formed at a high-rotational speed (more than 8000 rpm), and there are no obvious defects in each area of the joint section. The nugget zone (NZ) is a recovery recrystallization structure dominated by large-angle grain boundaries, with a grain size of about 4.9 μm. During grain growth, the texture is randomly and uniformly distributed, and the strength is balanced. The microhardness of the NZ increases significantly with the increase in rotational speed, and the fluctuation range of hardness value is small. The NZ β–Mg2Si is finer and significantly less than the base metal (BM). The heat dissipation of the thin plate is fast, so a Cu plate is used as the backing plate to slow down the steep temperature-drop process in the weld area. Compared with a low rotational speed, the precipitation amount of brittle phase Al–Cu–Mg–Cr and Al–Fe–Si–Mn is significantly reduced, which is conducive to improving the mechanical properties of the joint. At a high rotational speed, 12,000 rpm, the best tensile strength of the joint is 220 MPa, which is about 76% of the BM (290 MPa), and the highest elongation is 9.3%, which is about 77.5% of the BM (12%). The fracture mode of the joint is a typical plastic fracture.

Influence of tool velocity ratio on force-torque and mechanical properties of friction stir welded 2050-T84 Al-Li alloy plates

“…Higher tensile strength is obtained at lower tool velocity ratio (TVR) values during the welding process, lower TVR values frequently contribute to better plastic deformation and improved material flow. This process leads to enhanced mechanical properties, such as increased tensile strength, by promoting a more uniform distribution of residual stresses and grain structure refinement within the welded joint [38,39].…”

Sürtünme Karıştırma Kaynağı ile Birleştirilmiş 6061 Alüminyum Alaşımlı Sacların Mekanik Özellikler Yönünden İncelenmesi

“…İş parçasının özellikleri, takım boyutu, iş parçası boyutu, takım malzemesi gibi parametreler SKK süreci için önem arz eden diğer parametreleri oluşturmaktadır [42]. Literatürde yukarıda belirtilen çoğu parametrenin belirlenmesi için çalışmalar bulunmaktadır [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. Ancak bu çalışmada SKK için önemli olan bazı parametrelerin etkileri ele alınmıştır.…”

“…Çalışma kapsamında farklı kalınlıklardaki AA6061-T6 sacların farklı parametreler kullanılarak SKK ile birleştirilmesi ile ilgili incelenen makalelerin kodları ve bazı temel parametreler Tablo 1'de verilmiştir. [43] 800-1000 15-35 6 Kare (c) [44] 450-710 20-63 6 Silindirik (d) [45] 600-700 30-40 5 Yivli-Konik (e) [46] 1200-1600 40-80 5 Silindirik (f) [46] 1400 60 5 Silindirik (g) [47] 1100 120 6 Yivli (h) [48] 600-1400 300 0.5 Konik (i) [49] 1000-1200 100-150 6 Silindirik (j) [50] 2000-8000 300-1500 0.8 Yivli-Konik (k) [51] 560-1800 50-650 9 Yivli (l) [52] 900 78 2 Yivli (m) [53] 900-1500 45-135 6 Kare (n) [54] 1100 45-135 6 Yivli-Konik (o) [55] 500-1400 120 6 (p) [56] 750-1500 100-300 5 Yivli-Konik (r) [57] 1100 125-760 3 Silindirik…”

Mechanical Property Improvement in Dissimilar Friction Stir Welded Al5083/Al6061 Joints: Effects of Post-Weld Heat Treatment and Abnormal Grain Growth

“…Renowned as a versatile solid-state welding method, friction stir welding (FSW) is an alternative process to join Al alloys [ 9 , 10 , 11 ]. In FSW, material deformation occurs at a temperature lower than the melting point temperature of joined materials and consequently minimizes distortion and residual stresses in comparison with conventional welding methods [ 12 , 13 ]. Therefore, the issues that arise in the fusion joining of these alloys are absent in FSW [ 14 ].…”