Effect of processing temperature on tensile and fracture behaviour of UFG Al 6351 alloy processed by severe plastic deformation Amit Raturi a , Amit Joshi b,⇑ , K.K.S. Mer c , Sumit Raturi d a Department of Mechanical Engineering, THDC-IHET, Tehri 249124, India b Department of Mechanical Engineering, GBPIET, Pauri 246194, India c Institute of Technology Gopeshwar, 246424, India d Department of Mechanical Engineering, GBPIET, Pauri 246194, India article info Article history: Received 3 January 2020 Accepted 13 February 2020 Available online xxxx Keywords: Al Alloy Fracture toughness Multi axial forging abstract The aim of the present study is to investigate the Tensile and Fracture toughness of solution treated (ST), room temperature forged (RTF), and cryforged (CF) Al 6351 alloy. Microstructure evolution of ST, RTF, CF alloy were characterized by optical microscopy and TEM, while fracture surface after tensile test was studied by SEM. Al 6351 alloy was solutionized (ST) and subjected to room temperature forging and cry- oforging up to an effective true strain of 1.2, 1.8 and 2.4 (2, 4 and 6 cycles respectively). Optical micro- scopy followed by SEM and TEM were made to explain the grain refinement and strengthening mechanics. Fracture toughness tests were performed on RTF and CF alloy, and its deformation behaviour was related to its microstructural features. The improvement in fracture toughness K Q (27.62 MPA p m) of CF Al 6351 alloys was observed as compared to ST alloy (5.51 MPA p m). Ó 2020 Elsevier Ltd. All rights reserved. Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization. 1. Introduction Bulk ultrafine grained (UFG) material developed by top down approach have received a significant attention owing to their supe- rior tensile and fracture properties [1]. To achieve high specific strength i.e. strength to weight ratio in metals/alloys is prime objective of researchers working in the materials engineering. The demand of lighter and stronger materials is increasing due to its engineering design because materials such as aluminium (weight 7 kg) exhibits equal stiffness to steel (weight 10 kg) with equal width and length [2]. The aluminium alloys (density 2.7 g/ cm 3 ) have low tensile properties but excellent strength to weight ratio as compared to steel. Therefore, aluminium alloys are widely used in automotive, aerospace, marine industry, construction and transportation etc. Grain refinement plays a major role on strength enhancement of materials as reported in literature [3]. This leads to attention of material scientists to refine the grains well below than 1 mm to achieve refined microstructure in metals. Now a day’s top down approach such as severe plastic deformation techniques (SPD) are being widely used for refining grains in to the ultrafine regime [4]. Commonly used SPD methods are equal channel angular press- ing (ECAP), high-pressure torsion (HPT), multiaxial forging (MAF), and accumulative roll bonding (ARB [5]). In the past most of the work related to SPD techniques is based on ECAP, however very few researchers have reported the tensile and fracture properties of Al 6351 alloy subjected to multiaxial forging. Therefore, attempts have been made to investigate the influence of UFG microstructure on tensile and fracture properties of Al 6351 alloy processed by MAF at room and cryogenic temperature. Optical microscopy, SEM and TEM are used for the systematic study of microstructure evolution while tensile, vickers hardness and 3 Point Bend test are used for describing mechanical behavior. 2. Materials and experimental procedure 2.1. Raw materials Al 6351 alloy was procured from Tremor Alloys, Mumbai, India in T-6 treated condition in the form of 38 mm thick plate. Chemical composition and tensile properties of as received alloy is shown in Tables 1(a) and (b). https://doi.org/10.1016/j.matpr.2020.02.476 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization. ⇑ Corresponding author. E-mail address: amitj4765@gmail.com (A. Joshi). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: A. Raturi, A. Joshi, K. K. S. Mer et al., Effect of processing temperature on tensile and fracture behaviour of UFG Al 6351 alloy processed by severe plastic deformation, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.02.476