Metallographic diagram of 60 steel (tempered at 180°C)

Metallographic Analysis Report of S65C Steel Sample (carburizing and quenching at 180℃ )

1. Introduction

In order to analyze the microstructure and composition of S65C steel sample, Metallographic analysis was performed. The sample tested was zero point turned, carburized and quenched at 180℃.

2. Equipment Used in Testing

Metallographic testing of the sample was done using an optical microscope. The obtained images were analysed to determine the microstructure and composition of the material.

3. Preparation of Sample

The sample surface was cleaned using wet sand paper and water to remove any contaminants from the surface of the sample. Then it was zero point turned to achieve good smooth surface. Polishing was done using abrasive paper containing diamond particles and lapping paste to remove surface scratches and give good homogeneity to the sample.

4. Results

4.1 Microstructure

The microstructure of the sample was analyzed under the optical microscope and the following results obtained. Figures 1 and 2 below show the microstructure of the S65C steel sample.

Fig. 1 Microstructure of S65C steel (magnification x100)

Fig. 2 Microstructure of S65C steel (magnification x300)

The microstructure of the S65C steel sample reveals a homogenous and uniform distribution of ferrite and pearlite both in ferrite and pearlite portion. The microstructure of the sample is free from any signs of segregation or any other defect.

4.2 Composition Analysis

The composition of the sample was analyzed using spectrometer. The following composition results were obtained.

Table 1: Composition of S65C steel sample

Element Content (%) Carbon 0.60 0.7 Manganese 0.50 0.59 Silicon 0.25 0.35 Phosphorous 0.02 0.015 Sulfur 0.015 0.008

The composition of the sample is within the specified range for S65C steel.

5. Conclusion

The metallographic test reveals that the microstructure of the sample is uniform and free from any defects. The composition of the sample is also within the range specified for S65C steel.

Hence, the S65C steel sample has a homogenous microstructure with optimum composition.

The microstructural characteristics of SCM435 steel can be observed from the scanning electron microscope image above. This steel is generally used for manufacturing automobile components and its main possible chemical composition is as follows: 0.33-0.38% carbon, 0.7-0.9% manganese, 0.17-0.37% silicon, 1.2-1.8% chromium, 0.18-0.25% molybdenum, 0.25-0.4% nickel, 0.02-0.05% vanadium, and 0.035% phosphorus.

This steel material was heat-treated at 180°C, which is expected to increase its hardness and strength. From the image, it can be observed that the microstructure of SCM420 steel consists of ferrite and pearlite. The ferrite grain size is in the range of 0.5-0.7 μm. Similarly, the pearlitic grain size is around 1-1.2 μm. From this figure, it can be seen that the pearlitic grain size is greater than that of ferrite. It can be attributed to the higher cooling rate, which caused the ferrite grains to be finer.

It is observed that there are no other phases present in the microstructure of SCM435 steel after heat treatment. This indicates that the steel underwent complete homogenization during the process. This microstructure is also expected to ensure improved ductility and strength as compare to the steel’s untreated condition. Moreover, the presence of ferrite and pearlite matrix enhance the resistance of this steel material against stress corrosion cracking phenomenon, which can occur in some ferritic steels.