Caracterização mecânica de aço oriundo de pneus inservíveis

Abstract

In Brazil, in 2017, the number of new tires placed on the aftermarket was 60.424.080 units, totaling 839,863.47 tons, where at least 450.000 tons of tires are discarded per year. Among the materials that constitute the tires is steel, which has great value and utility in the industry, because due to its versatility can be used in various sectors of society and one of these utilities is in the construction of tires. The radial tire of a popular automobile contains between 15% and 25% of steel in its total mass, being distributed in different places of the tire and are in two types, wires and cables. Knowing this amount of discarded tires and the amount of steel in its structure, researches have been carried out with the purpose of characterizing and proposing uses for this steel. In this way, the objective of this work was to characterize, through mechanical properties, the steel coming from an unserviceable tire. For this purpose the tensile test was performed on two types of steels drawn from different locations of the tire. Four types of samples were made, two for each type of steel. The following mechanical properties were measured: tensile strength, yield strength, modulus of elasticity, resilience, toughness and ductility and compared with nominal steel properties. The tests indicated that steels from unserviceable tires can be characterized with modulus of elasticity for the wires of 157.37 GPa (AT1) and 130.63 GPa (AT2). For the cable were 84.86 GPa (CT3) and 83.68 GPa (CT4). The tensile strength limit for the wires was 1066.73 MPa (AT1) and 1731.88 MPa (AT2). And for the cables of 706.10 MPa (CT3) and 1727.56 MPa (CT4), being superior to SAE 1070 and SAE 1080 steels. The flow limits are also higher than the nominal properties; 1066.73 MPa (AT1) and 1444.23 MPa (AT2). For the cable were 706.10 MPa (CT3) and 1727.56 MPa (CT4). The ductility is 3 to 15 times smaller than nominal. According to the results presented, the materials may belong to ultra high strength steels (UHSS) used in engineering, such as in the automotive sector.