Discussion Material

Discussion

Based on the experiment conducted, experiment on Sample Preparation And Optical Microscope For Metallographic Observation, we was able to understand the procedure metallographic sample preparation. Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their metallic compounds, and their mixtures, which are called alloys. The stage of process to prepare the sample are cutting, hot mounting, grinding, polishing, and etching .

The early process of preparing the sample is cutting. During this process , we use abrasive cutting machine. By pressing the cutting knob slowly, the abrasive wheel was bring into the sample. The pressure applied need to be constant, the next process is hot mounting. We were using 10g of phenolic powder. The temperature has been set to 180 Celsius and the pressure at 200 bar. In mounting, the goal is to retain the true structure of the sample. Next , the sample obtain from hot mounting, undergo grinding process. Grinding is divided by t wo which is coarse grinding and fine grinding. This process is to obtain removes material using fixed abrasive particles that produce chips of the specimen material. Next step is polishing. It is to obtain a plane surface with minimal damage that can easily be removed during polishing in the shortest possible time. The last process is etching .There . There are several types of etchant used. The resulting structure that produces was ferrite and pearlite. Next, we observed the microstructure using microscope. The microstructure of the specimen with four different types of lens which is M5, M10, M20 and M40 . the different microstructure has been drawn. Under the magnification of 50, the structure of the sample looks neat and tidy. Under the biggest magnification which is at 400, we can see at the structure of the sample, there are a few f ew black spot which is known as defect. The microstructure obtain were ferrite and pearlite which is a hypoeutectoid steel. as we all known that the strength of a prealite is the lowest compared to other microstructure. They are soft and ductile.

Conclusion In a nutshell, the experiment goes as expected. We were able to determine the objectives of the experiment. The method of preparation of metallographic sample was understood. The five process of preparing the sample are very important such as cutting, molding, grinding, polishing and etching. at the end of this process, we will get the surface finish like a mirror at the specimen. Furthermore, we also understand the concept of etching and it purpose. Etching is done to bring out the structure of the polished specimen. After put the polished surface of the specimen to the chemical action of some appropriate reagent, we will see the result that will more perform by the specimen . the microstructure study are very important in the engineering subject. It is very important to be able to analyze the microstructure. The microstructure can be classify into metallic, polymeric and composite. Next , the structure of the material can be observe with the use of an optical microscope. The objective of the used and performed analysis from the microstructure has been achieved.

Discussion