Friction stir processing of AA1050/AA5052 composite produced by accumulative roll bonding process: Microstructure and mechanical properties

Abstract

A layered composite of AA1050-AA5052 alloys was fabricated through roll bonding, and accumulative roll bonding (ARB) and subsequently subjected to friction stir processing (FSP). In this process, the annealed AA5052 and AA1050 sheets are used as raw materials. At first, preheating at 200 °C for 6 min preceded the rolling process in an induction furnace, achieving a 67 % reduction in the cross-sectional area. Then, two ARB stages were conducted. At the flow, the FSP process was conducted at constant transversal speeds of 750 rpm and 1180 rpm. Microstructural details were analyzed using optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). Mechanical properties were assessed through tensile test, microhardness measurement, and wear test. The results showed that recrystallization occurred due to FSP applied to the rolled sheet. The tensile strength after ARB and FSP was measured as 270 and 150 MPa, respectively. These values show an increase of 3.3 times and 1.8 times, respectively, compared to annealed AA1050. The maximum elongation after ARB and FSP was measured at about 9 and 30 %. Work hardening and grain refinement, respectively, had a significant role in increasing the elongation of the AA1050/AA5052 composites created by ARB and FSP. Furthermore, FSP enhanced the wear resistance of the AA1050-AA5052 composite created with two ARB steps by 70 %.