Laboratory Testing and Evaluation Report - Essay Example

A theoretical study on their mechanical properties is also made. Samples of both finished materials having 1.2 mm thickness are tested against their mechanical properties which include universal testing and hardness testing. Another study of same grade of material which is kept under different process conditions is also made. Samples of 1.2 mm finished skin rolled SPCC steel versus 1.2 mm annealed SPCC steel were also studied in the same manner. As per discussing the chemical composition of the two materials, JISF (2011) had shown the allowable alloying percentage as given in Table 1.

Table 1 Symbol of Grade C (%) Mn (%) P (%) S (%) SPCC steel 0.15 max 0.60 max 0.10 max 0.050 max SPCG steel 0.02 max 0.25 max 0.020 max 0.020 max However, the mill test certificates of the samples reveal following composition as given in Table 2 of the two materials: Table 2 Symbol of Grade C (%) Mn (%) P (%) S (%) SPCC steel 0.10 0.23 0.02 0.009 SPCG steel 0.002 0.17 0.019 0.007 As evident from the steel grades, commercial SPCC steel is applied in forming applications, and extra deep drawing SPCG steels are meant to be deep drawn.

These steels are widely used in various applications. SPCC steel is being used in the making of door hinges, pans, casings, galvanised steels, and profile sheets. Whereas SPCG steel is utilised in deep drawing applications such as motor cycle fuel tank, chain cover, etc. Chemical composition of the alloy steel is incredibly important because each element has its own role in varying the material properties. For instance, rust is a vulnerable defect of steels, and rust is basically the result of iron oxide formation (Blair and Stevens, 1995).

Absolute iron is absolutely susceptible to rust. With the introduction of other elements, rust exposure is decreased. Higher percentage of alloying material decreases rust possibility and lowers percentage of alloying material; alloying material increases the risk of rust formation. Therefore, SPCG steel is more susceptible to rust as compare to SPCC steel. Similarly, elements present in alloying composition also affect mechanical properties of the steel. Mechanical properties are to be assessed in this laboratory testing and material evaluation case study. 1. Structure of Materials Figure 1 (Blair and Stevens, 1995) is the iron-carbon phase diagram.

It shows the percentage of Carbon influencing the microstructure of the steel. It is a low-carbon steel which contains carbon between 0 02 % and 0.15 %. Both material grades are the dead mild steel comprises mainly alpha ferrite and the traces of pearlite in its microstructure. These are extremely ductile and are therefore usually utilised as sheets for forming and drawing operations. Its microstructure seems white as of very less insignificant pearlite content steel. Both SPCC and SPCG sample materials lies in pearlite + ferrite region.

Figure 1 2. Expected Theoretical Results The chemical composition of these steel is vitally important for assessing mechanical properties. It is because lower carbon percentage in steel will affect the making of material, lowering its hardness, and a higher percentage of carbon will yield a harder material. Therefore, according to theoretical analysis, SPCC steel should be harder than SPCG steel due to a higher percentage of carbon. JISF (2011) specifies the range for the two material grades, as mentioned in Table 3, of different mechanical prope