Hot Workability and Processing Map of Ultrafine-Grained Al/SiC Composite with Different Reinforcement Sizes Under Compre
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UCTION
DEMAND for the usage of lightweight materials in automotive, aerospace, defense and structural applications drastically increased in recent years to improve fuel efficiency and reduce environmental pollution. Von et al.[1] mentioned the feasible approach to achieve light weighting is the use of aluminum (Al) alloys and their composites. Von et al. also proposed the use of particulate reinforced aluminum matrix composites (AMCs) in numerous engineering applications because of the combined properties of Al alloy and reinforcement. Further improvement of the mechanical properties of AMCs can be achieved via severe plastic deformation (SPD).[2–5] SPD processing modifies the microstructure of AMC in ultrafine-grained (UFG) and/
O.B. BEMBALGE and S.K. PANIGRAHI are with the Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India. Contact e-mail: [email protected] Manuscript submitted February 13, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
or nano-structured (NS) regimes, which ultimately increases the mechanical properties.[6,7] Severely deformed (UFG/NS) AMCs possess a better specific strength and modulus, low coefficient of thermal expansion and wear resistance.[8–11] Unfortunately, forming of UFG/NS AMC components with complex shapes at room temperature is extremely difficult because of their higher strength and low ductility as mentioned by Kil et al.[12] To improve the ductility during forming, thermo-mechanical treatments can be given, which enable the UFG/NS AMCs to be formed easily in complex geometries. Xu et al.[13] stated that it is important to categorize the forming process variables such as temperature and strain rate while forming for clean and efficient deformation of UFG/NS AMC. The ease of deformation of a material is called as workability. Sahoo et al.[14] mentioned that workability of composite materials can be studied via hot deformation and processing maps. Their work provides a safe processing regime for a temperature window between 350 C to 400 C for a strain rate of 0.001 s1. Processing maps are a graph of flow stress vs. deformation variables (strain, strain rate and temperature)[15] that defines the workability of UFG/NS AMC materials. Mokdad et al.[16] explained that the optimal
parameters for deformation in stable compared with unstable zones can be defined by a processing map. Wu et al.[17] used the dynamic materials model (DMM) to construct the processing map, which can also be used to evaluate the optimal deformation variables for different UFG/NS AMCs. Separately, Bhat et al.[18] mentioned that the existence of reinforcement particles (SiC) in the Al matrix makes hot workability of UFG/NS AMCs much poorer than the base Al alloy. Prasad et al.[19] developed processing maps of Al2O3/Mg composites with nano-particles and determined that the composite’s deformation behavior is quite similar to the alloy at higher strain rates, while being different at low strain rates. Li et al.[20] studied the hot workability of B4C (10 lm)/AA6061 composite
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