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Cryorolling of Aluminum Alloy Sheets and Their Characterization: A Review
Published in Kakandikar Ganesh Marotrao, Anupam Agrawal, D. Ravi Kumar, Metal Forming Processes, 2023
Kandarp Changela, K. Hariharan, D. Ravi Kumar
In the last decade, severe plastic deformation (SPD) has been established as an effective method for the production of bulk ultrafine-grained (UFG) metallic materials [11–14]. Severe plastic deformation is a method of processing metals with large plastic deformation (plastic strain > 1.5) to create bulk UFG materials with an average grain size in the sub-micrometer or the nanometer range. In SPD, the metal undergoes intense plastic strain, leading to large shear deformation. The original coarse grains become smaller and smaller with an increasing strain that results in nanoscale grains with high crystal misorientation. These highly misoriented sub-micrometer sized grains lead to a bulk material with improved mechanical properties [15]. In order to fabricate UFG materials, many different SPD processes have been proposed, developed, and evaluated. These techniques include equal channel angular pressing (ECAP) [16], high pressure torsion (HPT) [17], accumulative roll bonding (ARB) [18], multi-axial forging [19], asymmetric rolling (ASR) [20], cryorolling (CYR) [21], and constrained groove pressing (CGP) [22]. These SPD methods are schematically shown in Figure 5.1 [17, 20, 23, 24].
Introduction to Surface Tailoring of Metals
Published in B. Ratna Sunil, Surface Engineering by Friction-Assisted Processes, 2019
Developing nanostructured bulk metals or nanostructuring the surface itself without altering the microstructure of the core of the metal can be achieved by several methods which include a top-down approach and bottom-up approach as schematically explained in Figure 1.10. In the top-down approach, bulk nanostructured metals are developed from coarse-grained metals by introducing enormous strain through mechanical processing. Severe plastic deformation (SPD) techniques such as equal channel angular pressing (ECAP), constrained groove pressing (CGP), accumulative roll bonding (ARB), twist extrusion (TE), high-pressure torsion (HPT), and friction stir processing (FSP) are a few examples of the top-down approach [13]. The top-down approach gives bulk nanostructured structures which can be readily used in different industrial applications where high specific strength can be achieved by using lower weight metals. In the bottom-up approach, atom by atom are added to develop clusters, and the number of clusters is used to produce nanoparticles. These nanoparticles are consolidated to develop bulk nanostructured materials. Chemical vapor deposition (CVD), physical vapor deposition (PVD) and sol-gel methods are a few examples of the bottom-up approach [14]. Consolidating the produced nano-particles is a necessary follow-up process to develop bulk nano-structured components.
Synthesis of Nanomaterials
Published in Rajendra Kumar Goyal, Nanomaterials and Nanocomposites, 2017
Severe plastic deformation (SPD) is the metal-forming process in which a very large plastic strain is introduced into a bulk metal in order to create the ultrafine-grained metals. SPD process is employed to produce high-strength and lightweight parts with environmental harmony. In this, a billet is heavily strained under high-imposed pressure, resulting in nanostructured materials with almost free porosity. There are two most commonly used SPD techniques: high-pressure torsion (HPT) and equal channel angular pressing (ECAP). In HPT, disc-shaped (Figure 5.3a) sample with a diameter of 10–20 mm and thickness of 0.2–0.5 mm is put between anvils and compressed under a high pressure (approximately several GPa). The lower anvil turns, and friction forces result in shear straining of the sample. Due to the high-imposed pressure, the sample under deformation does not break even at high strains and it can produce a homogeneous nanostructure with a typical grain size of about 100 nm or less. In case of ECAP, the ingot is pressed in a special die through two channels with equal cross sections intersecting at an angle φ, usually 60° < φ < 135° and often φ = 90° (Figure 5.3b). In each pass, sample gets a strain of about 1. ECAP refines the microstructure of pure metals, alloys, and intermetallics using straining with one pass or a few [16].
Surface treatment response of AISI 2205 and AISI 304L steels: SMAT and plasma-nitriding
Published in Surface Engineering, 2019
Digvijay Singh, Atul M. Gatey, Rupesh S. Devan, Vinícius Antunes, Fernando Alvarez, Carlos A. Figueroa, Akshay A. Joshi, Santosh S. Hosmani
Nanocrystalline grain-structure at the surface of the alloys is advantageous in enhancing the surface properties. Nano- or submicron-size grains can improve the corrosion resistance of the alloys [1]. Severe plastic deformation (SPD) is one of the processing routes to achieve the nanostructure in the alloys. Various SPD methods like equal channel angular pressing (ECAP), high-pressure torsion (HPT), accumulative roll bonding (ARB), hydrostatic extrusion (HE), surface mechanical attrition treatment (SMAT), ultrasonic shot peening (USP), etc are known for the grain refinement [1,2]. Out of these methods, SMAT and USP are the surface-treatment methods. SMAT is becoming popular in recent years because of its capability to alter the surface properties of various alloys [1,3–9].
The mechanical compression performance of ultra-fine grained stainless steel pyramidal lattice core
Published in Mechanics of Advanced Materials and Structures, 2021
Hamdi Kuleyin, Recep Gümrük, Harun Yanar, Muhammet Demirtaş, Gençağa Pürçek
To improve the specific mechanical properties and performance of current engineering materials and structures, there is an extensive focus on different material processing methods such as severe plastic deformation (SPD) techniques etc. as well as the development of new material and manufacturing technology. SPD processes, including well-known methods like equal-channel angular pressing/extrusion (ECAP/E), accumulative roll-bonding (ARB), MIF (Multiple Isothermal Forging), and high-pressure torsion (HPT) etc., are techniques of achieving ultrafine-grained (UFG) materials, by which the bulk materials are subjected to excessive plastic deformation [35]. Among them, ECAP is the most popular one to achieve bulk UFG microstructure from different materials. Many studies have been performed on processing and characterization of ECAPed materials, most of which have been focused on the understanding of deformation characteristic during ECAP, resulting microstructural behavior, and main mechanical properties [36, 37]. From the results of the studies, many review papers have also been published in this area, and more information regarding the results can be found in Sepahi et al. [38] reporting that ECAP was used to obtain UFG Mg alloys in better mechanical properties. Gao and Cheng [39] studied the effect of ECAP on sliding wear properties of Cu alloy and concluded that wear resistance and load-bearing capacity of the alloy during dry sliding improved. Bryła et al. [40] studied the effect of HPT on the microstructure and mechanical properties of Mg alloy. Bézi et al. [41] performed uniaxial tensile tests and microstructural examination for UFG Ti obtained by a combination of MSF and rolling methods.
Parametric optimization for friction stir processing in Al-Zn-Mg-Cu alloy
Published in Materials and Manufacturing Processes, 2022
Yang Wenjing, Ding Hua, Li Jizhong
Severe plastic deformation (SPD), an efficient way of grain refinement, gives rise to high performance and machinability for materials. Common techniques of SPD include accumulative roll-bonding (ARB), [1] equal channel angular processing (ECAP), [2] multi-axial alternative forging (MAF), [3] high-pressure torsion (HPT), [4] and friction stir processing (FSP). [5 FSP demonstrates the advantages of simple operation, low-energy consumption, and environment-friendly,[6and is considered a promising SPD technique. Developed from friction stir welding, FSP is an effective and feasible method in microstructural improvement[7,8] structural joint[9] surface treatment[10] and composite preparation[11] for 7xxx aluminum alloy. The main processing equipment of FSP is astir tool consisting of an integration of shoulder and pin. Implementing the processing is as follows: the stir tool is pressed into the plates with high-speed rotation and moves in a route for the processing area.[12,13] The material flows around and backward of the pin and severe deformation is achieved. The combined effect of SPD and heat conduction induces the final ultrafine-grained microstructure named stir zone (SZ). Previous works[13,14] indicated that a remarkable refinement of microstructure and an enhancement of comprehensive performance could be obtained in SZ. Li Kan[13] summarized that the inherent defects of materials from casting could be eliminated in SZ; moreover, the ductility and hardness of materials could be significantly enhanced. Liu[15] also reported the fine grain was achieved in SZ, and the ductility was twice as the rolled material. Generally, the heat-affected zone (HAZ) and the thermo-mechanically affected zone (TMAZ) inevitably exist around the SZ.[16,17] El-Rayes[17] mentioned HAZ underwent the thermal cycle and no plastic deformation. Thus, the microstructure reserved the grain morphology of the parent material. TMAZ experienced heat conduction and low deformation strain. Microhardness declined in HAZ and TMAZ. K.V. JATA[18 undertook the analysis of mechanical properties in an FSW material containing TMAZ and HAZ, and the results showed the strength level and elongation had been reduced in 30 pct and 60 pct, respectively; and fracture path was detected in the HAZ. John[19] demonstrated residual stresses in the HAZ played a vital role in crack growth for FSW 7050-T7451 aluminum alloy. As pointed out by many studies,[18–20] with the non-uniform microstructure in HAZ and TMAZ, the fracture is easy to occur in these zones, leading to a deterioration in mechanical properties of materials. Besides, the weak zones limit the application of FSP in large-scale plates. Thus, Double-sided Friction Stir Process (DFSP) has been proposed in our previous work to eliminate these microstructural defects.[21]