Characteristics of Different Materials - Lab Report Example

Whereas steel has a carbon content that is less than that of pig iron, its carbon content is more than that of wrought iron. Moreover, steel has such qualities as elasticity, hardness, as well as strength, which depend on heat treatment and composition (Mäkeläinen and Hassinen 488). Consequently, it is categorized as either having low, medium, or high carbon content. On the other hand, aluminum is a silvery-white metallic element that is ductile and has a low density as well as a high strength-to-weight ratio and is mainly bauxite. Owing to its good thermal and conductive properties, aluminum is usually used in forming hard light corrosion-resistant alloys. Similarly, a polymer is defined as a chemical compound that is formed through a process known as polymerization, and it consists of repeating structural units (Cheremisinoff 1). Inherently, polymers are normally characterized by their light weight and their ability to resist corrosion and reaction.

Materials and methods
The dumbbell specimens were put under tensile forces through a horizontal tensile testing machine. Consequently, the diameter of the specimen was obtained by use of a vernier caliper and recorded before the test commenced. Moreover, during the application of the load, two cameras were used in determining the diameter of the specimen. Subsequently, the cross-sectional area of the specimen was obtained and together with the load, both the engineering stress and the true stress were calculated by the following equations.

The process was repeated for all the materials.
Consequently, a horizontal tensile force was applied to the specimen. The elongation and the new diameter of the specimen, due to the applied load were similarly obtained through the use of a VI monitor and the cameras, and they were recorded. Using the load (KN), the diameter (mm), and the elongation (m), engineering and true stress, engineering strain, yield stress *0.1 percent offset, Young modulus, ductility, ultimate tensile stress, and work fracture were also obtained.

Davis defines young elastic modulus as the measure of the resistance of a material to elastic deformation (32). It is equal to the slope of a stress/strain curve in an elastic region. Moreover, according to Davis, the ductility of a material describes the ability of a material to deform permanently before failure (37). It is the engineering strain of failure.
Davis claims that work fracture is equal to the area under the stress-strain curve, and its unit is work per unit volume (Nm/m3) (45).

More importantly, the ultimate tensile strength refers to the maximum amount of stress a material can bear. It is obtained from the engineering stress-strain curve as the highest point.

Conclusion
From the tensile test conducted on materials A, B, and C, the young modulus, yield strength, and ultimate tensile strength were obtained. Material A had the highest young modulus with a value of 190 GPa, and it was followed by material B and finally material C. Consequently, from the results it is clear that as the materials become brittle, the Young modulus tends to become higher. It was also noted that the polymer achieved the highest engineering strain, of 0.57, and was closely followed by steel with 0.35 and aluminum with 0.1. Whereas the hardness of aluminum and steel differed with a margin of 150 VHN, their characteristics were almost similar, but on the other hand, the hardness of aluminum and polymer was 6 VHN, even though their characteristics depicted significant variations.

Notably, the error values were trivial and did not cause any significant change to the results of the experiment. Moreover, most of the errors were systematic errors and are mainly normal errors in an experiment. Consequently, from the results of the experiment, it was clear that material A depicted similar qualities as low alloy steel AISI, 3140, normalized, whereas material B had the same characteristics as zinc-aluminum alloy, ZA-8 general casting (Mäkeläinen and Hassinen 488). In addition, material C was identified as polyamide (nylon) (type 66 modeling). Read More