Abstract
The A356 alloy has been widely used in automotive components, such as wheels and brake disks, because it is an excellent lightweight material with high corrosion resistance and good mechanical properties. Recently, to reduce the weight of brake disks, the Fe-A356 hybrid brake disk has been suggested. Because brake disk quality is directly related to driving safety, the T4/T6 heat treatment of centrifugally cast A356 alloys were performed to enhance the mechanical properties and reduce micro-segregation. The solid-solution heat treatment followed by annealing caused the formation of Mg-rich intermetallic compounds on the grain boundaries of the Al matrix, decreasing the average hardness of the alloys by 13 HV. In contrast, the solid solution followed by water quenching (T4) reduced the area fractions of the intermetallic compounds and increased the average hardness by 11 HV. The T6 heat-treated A356 alloys, which were influenced by the formation of the Guinier–Preston zone exhibited a relatively higher average hardness, by 18 HV, compared to T4 heat-treated A356 alloys.
Highlights
As exhaust emission standards and regulations have become increasingly strict, many automobile manufacturers have attempted to reduce vehicle exhaust emissions by improving power transmission efficiencies using several strategies, such as the reduction of the weight of vehicles and enhancement of the combustion process [1,2,3]
The brake disk is one that has not been reduced in weight, and most of them are made of heavyweight cast iron [6,7]
In other parts of the brake disk, A356 alloys, which are lighter than the gray cast iron and of higher thermal conductivity, were used to reduce the weight and improve the heat dissipation of the disk
Summary
As exhaust emission standards and regulations have become increasingly strict, many automobile manufacturers have attempted to reduce vehicle exhaust emissions by improving power transmission efficiencies using several strategies, such as the reduction of the weight of vehicles and enhancement of the combustion process [1,2,3]. Many automobile components, such as transmission cases, frame parts, and wheels, have been replaced with aluminum alloys because their light weight is beneficial to improve fuel efficiency and reduce exhaust emissions [4,5] Among these components, the brake disk is one that has not been reduced in weight, and most of them are made of heavyweight cast iron [6,7]. Cast-iron brake disks are manufactured mainly by gravity casting; they are inexpensive and have an excellent wear resistance [8] These disks have some problems with respect to the weights and poor heat dissipation performance, generating high temperatures during harsh driving conditions [9,10,11]. In other parts of the brake disk, A356 alloys, which are lighter than the gray cast iron and of higher thermal conductivity, were used to reduce the weight and improve the heat dissipation of the disk
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