Investigation on the corrosion resistance of 3003 aluminum alloy in acidic salt spray under different processing states

3003 aluminum alloy exhibits commendable corrosion resistance, ease of processing, and good formability, rendering it extensively utilized across many industrial sectors. In this study, the corrosion behavior of 3003 aluminum alloy in a homogenized state and after hot extrusion deformation in an acidic salt spray environment for different times was studied. The microstructure of the 3003 aluminum alloy in the homogenized state and after hot extrusion was characterized using scanning electron microscopy (SEM), optical microscope (OM), laser scanning confocal microscope (LSCM) etc., while electrochemical methods were employed to study the difference in corrosion resistance between these two states. The results show that corrosion pits on the surface of the homogenized 3003 aluminum alloy increase with time, and corrosion extends along the second phase arrangement, while the hot extruded 3003 aluminum alloy mainly exhibits corrosion pit extension. The grain size of the homogenized 3003 aluminum alloy is larger than that of the hot extruded state, and the second phase is distributed in a reticular pattern. Hot extrusion deformation ensures not only a uniform distribution of the second phase in the 3003 aluminum alloy but also a reduced grain size, an increased grain boundary density, a heightened electrochemical activity in acidic environments, and an augmented pitting density. Compared with the homogenized 3003 aluminum alloy, the pitting density, maximum pitting depth, and weight loss of the hot extruded state are increased

Corrosion behavior of homogenized and extruded 1100 aluminum alloy in acidic salt spray

The 1100 aluminum alloy has been widely used in many industrial fields due to its high specific strength, fracture toughness, excellent thermal conductivity, and corrosion resistance. In this study, the corrosion behavior of the homogenized and hot-extruded 1100 aluminum alloy in acid salt spray environment for different time was studied. The microstructure of the 1100 aluminum alloy before and after corrosion was characterized by an optical microscope (OM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and a laser scanning confocal microscope (LSCM). The difference in corrosion resistance between the homogenized and extruded 1100 aluminum alloy was analyzed via the electrochemical method. The results indicate that after hot extrusion at 400 °C, the microstructure of the 1100 aluminum alloy changes from an equiaxed crystal structure with (111) preferentially distributed in a fibrous structure with (220) preferentially distributed. There was no obvious dynamic recrystallization occurring during extrusion, and the second-phase particles containing Al-Fe-Si were coarse and unevenly distributed. With the increase in corrosion time, corrosion pits appeared on the surface of the 1100 aluminum alloy, and a corrosion product layer was formed on the surface of the homogenized 1100 aluminum alloy, which reduced the corrosion rate. After 96 h of corrosion, the CPR of the extruded samples was 0.619 mm/a, and that of the homogenized samples was 0.442 mm/a. The corrosion resistance of the extruded 1100 aluminum alloy was affected by the microstructure and the second phase, and no protective layer of corrosion products was formed on the surface, resulting in a faster corrosion rate and deeper corrosion pits

Hot deformation behavior and processing maps of an as-cast Al-5Mg-3Zn-1Cu (wt%) alloy

One of the key issues limiting the application of Al-Mg-Zn-Cu alloys in the automotive industry is forming at a low cost. Isothermal uniaxial compression was accomplished in the range of 300–450 °C, 0.001–10 s−1 to study the hot deformation behavior of an as-cast Al-5.07Mg-3.01Zn-1.11Cu-0.01Ti alloy. Its rheological behavior presented characteristics of work-hardening followed by dynamic softening and its flow stress was accurately described by the proposed strain-compensated Arrhenius-type constitutive model. Three-dimensional processing maps were established. The instability was mainly concentrated in regions with high strain rates or low temperatures, with cracking being the main instability. A workable domain was determined as 385–450 °C, 0.001–0.26 s−1, in which dynamic recovery (DRV) and dynamic recrystallization (DRX) occurred. As the temperature rose, the dominant dynamic softening mechanism shifted from DRV to DRX. The DRX mechanisms transformed from continuous dynamic recrystallization (CDRX), discontinuous dynamic recrystallization (DDRX), and particle-stimulated nucleation (PSN) at 350 °C, 0.1 s−1 to CDRX and DDRX at 450 °C, 0.01 s−1, and eventually to DDRX at 450 °C, 0.001 s−1. The eutectic T-Mg32(AlZnCu)49 phase facilitated DRX nucleation and did not trigger instability in the workable domain. This work demonstrates that the workability of as-cast Al-Mg-Zn-Cu alloys with low Zn/Mg ratios is sufficient for hot forming

High temperature deformation behavior of permanent casting AZ91 alloy with and without Sb addition

The elevated temperature deformation behavior of permanent cast magnesium alloy AZ91 with and without Sb addition has been investigated using slow strain rate (5.0 × 10 −4 s −1 ) elevated temperature tensile and constant load creep testing at 150 • C and 50 MPa. The alloy with 0.4 wt% Sb showed a higher elevated temperature tensile strength and creep resistance due to the formation of thermal stable Mg 3 Sb 2 precipitates and a smaller microstructure as well as the suppressing of the discontinuous precipitation. Plastic deformation of AZ91 based alloys is determined by motion of dislocation in basal plane and non-basal slip systems. The dislocation motion in a slip system is influenced by temperature, precipitates and other lattice defects. Dislocations jog, grain boundaries and/or precipitates are considered as obstacles for moving dislocations. The (0112) deformation twinning were founded in the creep process by TEM. Cross slip of dislocations was taken into account as the main softening mechanism for permanent cast AZ91 alloy during elevated temperature deformation process. C 2002 Kluwer Academic Publisher

Effect of Ce on the Microstructure and Corrosion Resistance of Al-5Mg-3Zn-1Cu Alloy

The effects of different Ce content on the microstructure and corrosion resistance of Al-5Mg-3Zn-1Cu alloy in metal mold gravity casting were studied in this paper. The microstructure of the alloy was characterized by scanning electron microscope (SEM) and X-Ray diffractometer (XRD). The corrosivity of all alloys in 3.5 wt.%NaCl solution was studied by electrochemical and immersion corrosion techniques. The results show that the microstructure of the alloy is mainly composed of α-Al, T phase, and Al2Cu phase. Ce can refine the organization of the alloy, but when the addition of Ce is higher than 0.25 wt.%, a massive Ce-rich phase appears in the alloy. The results of a potential polarization test show that the corrosion potential of the alloy increases obviously from −1.253 V to −1.193 V with the increase in Ce content in the alloy

Strengthening and toughening mechanisms of an ultrafine grained Mg-Gd-Y-Zr alloy processed by cyclic extrusion and compression

Cyclic extrusion and compression (CEC) was implemented to process the Mg-Gd-Y-Zr alloy. Microstructure characters, including the matrix grain, precipitates and texture evolution, were tried to correlate with the mechanical performance of the post-processed alloy. Results show that after 14 passes of CEC, the average grain size of GW102K is greatly refined to ~100–200 nm. Secondary-phase particles are broken due to the occurrence of tension tearing and shearing fracture. Quantitative texture analysis elucidates that CEC weakens the initial fiber texture of the extruded GW102K. Unlike most of the severe plastic deformed Mg alloys, the CEC processed GW102K alloy follows the normal Hall-Petch equation, which is closely associated with the disintegrated texture as well as the nanoscale second-phase particles. A considerable increase in elongation is witnessed and the introducing of rare-earth elements (RE) is found to change the deformation mechanisms of the Mg alloy by facilitating non-basal slip systems, twinning and shear bands

Microstructure and enhanced mechanical properties of an Mg-10Gd-2Y-0.5Zr alloy processed by cyclic extrusion and compression

The evolution of microstructure and texture of an extruded GW102K Mg alloy processed by cyclic extrusion and compression (CEC) at 450 °C were investigated. Tensile tests were performed at room temperature and strain rate 5 × 10−3 s−1. The results show that the microstructure was effectively refined, and the initial fiber texture became disintegrated and developed a new texture after 14 CEC passes. It was found that the strength and ductility were simultaneously increased compared with the as-extruded alloy. In particular, the elongation and yield strength were related in a line relationship having a positive slope. As the texture changed and texture intensity decreased, substantial grain refinement was observed. The hard second-phase particles were considered to be responsible for the uncommon properties of the GW102K alloy processed by CEC

Effects of ECAP and Annealing Treatment on the Microstructure and Mechanical Properties of Mg-1Y (wt. %) Binary Alloy

Microstructure and mechanical properties development of extruded Mg-1Y (wt. %) binary alloy during equal channel angular pressing (ECAP) with route Bc at 400 °C, and subsequent annealing treatment between 300–400 °C at different holding time of 5–120 min were investigated using an optical and scanning electron microscope (SEM), electron back scattered diffraction (EBSD), tensile test, and hardness test. The grain size of as-extruded material (~10.9 μm) was refined significantly by 1-pass ECAP (~5.8 μm), and resulted in a remarkably enhanced elongation to failure (EL) (~+62%) with a slightly decreased ultimate tensile strength (UTS) (~−3%) comparing to the as-extruded condition (EL = 11.3%, UTS = 200 MPa). The EL was further increased to 27.3% (~+142%) after four passes of ECAP comparing to the as-extruded condition, which was mainly caused by the much more homogenized microstructure. The split basal poles with about 60° rotations to the extruded direction (ED), the relatively coarsened grain size by static recrystallization (SRX) and post-dynamic recrystallization (PDRX) after four passes of ECAP might be responsible for the decreased strength with increasing ECAP pass. During the annealing treatment, recovery dominantly occurred at 300 °C, SRX and grain growth emerged at 350 °C and 400 °C, respectively. Meanwhile, the grain grew and hardness decreased rapidly even within 5 min for 1-pass ECAPed material at 400 °C, indicating a larger grain boundary mobility of ECAPed materials induced by higher deformation energy than the as-extruded ones