Materials and manufacture 2 - Essay Example

The six different properties of the seven different materials are identified in terms of their standard definition and then the typical values are further tabulated in SI units in the following table 1 for the purpose of comparison. The material specifications for metals such as low carbon steel and aluminum-zinc alloys can be found in American Society of Testing and Materials (ASTM) standards and Aluminum Association standards respectively. For example, ASTM A36 (American Society of Testing and Materials[ASTM], 2011 ) is a low carbon structural steel available in various forms such as plates, bars, sheets and rolled products.

The properties of A36 are included in table 1. Aluminum-Zinc alloys are designated as 7000 series Al alloy by Aluminum Association based in Arlington, Virginia. 7000 series however include the entire gamut of products like flats, long, castings and so on. The table 1 provides the properties of aluminum-zinc castings only. The thermoplastic polymers are available in form of various brands in the market. The injected molded polymers parts are widely used in industries and hence included in the property table 1.

As regards wood, the properties of solid Beech and Birch are included in table 1. Table 1 Properties of materials (http://www.matweb.com & http://www.matbase.com) Material Yield Strength In MPa Young Modulus In MPa % Elongation Electrical Resistivity In µ?-m Thermal Conductivity in W/m-K Density In gm /cm3 Low Carbon Steel 250 210000 23 0.1612 43-54 7.85 Aluminum Zinc Alloys 205 71000 1 0.038-0.057 121-155 2.80 Acetal Coplymer 37-120 586-12100 1.0-250 1.0e+17 0.231-0.31 1.32-1.54 HDPE 9-43 180-1570 3.20-2080 1.00e+18 0.288-0.400 0.918-1.05 LDPE 7.

7-136 110-449 13.5-800 1.0e+17 0.30-0.33 0.91-0.98 BEECH WOOD 130** 10000-18000 * * 0.04-0.4 0.66-0.780 BIRCH PLY 134** 14500-16500 * * 0.04-0.4 0.73 Note. * Woods and ply are not ductile materials and they are good electrical insulators. 130** and 134** represent Ultimate Tensile strength. The standards such as ASTM again provide the measurement techniques of both mechanical and physical properties of materials. Depending on the techniques there may be wider variation in mechanical properties which are dependent on the geometry of the test piece.

The physical properties are however constant across all geometries of the test piece but found to vary depending on the varied chemical composition. For example, the carbon content in the ASTM A36 material can influence the thermal conductivity values. Similarly, the polymers namely, Acetal Copolymer, HDPE, LDPE exhibit wide ranges of variation in both physical and mechanical properties across various brands available in the market. Hence the values tabulated in table 1 are all typical values.

The actual values shall be taken from suitable sources for a specific application. THE CONCEPT OF THE QUANTITATIVE PROPERTIES Strength: It can be defined either in terms of Yield Tensile Strength or Ultimate Strength depending on the desired application. Yield Tensile Strength is the axial load applied per unit area just required to initiate plastic deformation beyond the elastic range of the material. This plastic