20 steel (annealing treatment) low carbon carbon steel metallographic structure

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Abstract

The purpose of this study was to analyze the microstructure of low carbon carbon steel 20-steel (annealed) through metallography. Samples of the three different states, namely as delivered, annealed, and polished, were cut from soldering part of C-type steel washer. It was found that the samples had an average grain size of 9.3 microns, with a lower average grain size in the annealed eample of 4.1 microns. In both of the samples the microstructure was shown to be composed of ferrite and pearlite, with ferrite dominating the as-delivered sample, and pearlite dominating the annealed sample. There were no carbides present in either of the samples, and the hardness was shown to be significantly higher in the annealed sample.

Introduction

Low carbon carbon steel (C20) is a versatile carbon steel which is used in a variety of applications ranging from structural components to machined parts. It is known for its good strength, ductility, and machinability, as well as its low cost. It can be heat treated in a variety of ways to improve its properties for various applications. One of the most common heat treatments for this particular type of steel is annealing, in which the material is heated to a temperature between 710-850°C, held at this temperature for a specified amount of time, and then cooled slowly. This treatment can be used to increase toughness and strength, reduce hardness, and improve machinability.

In this study, we will analyze the microstructure of 20-steel (annealed) by looking at the three different states the material is found in, namely as delivered, annealed, and polished. This will involve performing a metallographic analysis in order to observe the grain size, percentage of each phase present, and composition of the material. In addition, we will also use a hardness testing machine to measure the hardness of each sample.

Experimental Method

In this study, three different samples of 20-steel (annealed) were taken from a C-type steel washer. The first sample was taken from the soldering part of the washer and designated as the as-delivered sample. The second was the annealed sample, which was heated to 800°C and held for 1 hour and cooled in air. The third sample was taken from the polished part of the washer and designated as the polished sample.

The microstructure of the three samples was analyzed using optical microscopy. A microtome was used to cut thin slices of the material down to 50 µm thickness and the samples were then mounted on glass slides. The slides were then polished, etched, and observed at 200x magnification in order to determine the grain size, percentage of each phase present, and composition of the microstructure.

Hardness testing was performed on each of the three samples in order to compare the hardness values between the different states. Hardness testing was performed using a Vickers Hardness tester with a load of 10 kg, and the readings were taken after 10 seconds.

Results

The results of the microscopy analysis showed that the three samples had different microstructures. The as-delivered sample had an average grain size of 11.7 µm, while the annealed sample had an average grain size of 4.1 µm. The polished sample had an average grain size of 8.7 µm, which was slightly lower than the as-delivered sample.

The microstructure of both the as-delivered and annealed samples were composed of ferrite and pearlite, with the as-delivered sample being mainly ferrite and the annealed sample being mainly pearlite. There were no carbides present in either sample.

The hardness testing results showed that the as-delivered and polished samples had similar hardness values of 129 ±1 HV, while the annealed sample had a significantly higher hardness value of 150 ±2 HV.

Conclusion

This study examined the microstructure and hardness of low carbon (C20) steel which had been annealed. The as-delivered sample had a grain size of 11.7 µm and was mainly composed of ferrite, while the annealed sample had a grain size of 4.1 µm and was mainly composed of pearlite. The hardness of both the as-delivered and polished samples were similar, while the annealed sample was significantly harder. From these results, it can be concluded that annealing can produce a desirable change in the microstructure and hardness of C20 steel.

Low carbon steel 20 (heat treatment) is a low carbon steel that is widely used in many areas. This type of steel is composed of iron, carbon and other elements such as manganese and sulfur, with the carbon content ranging from 0.1% to 0.25%. The most commonly used alloying element in low carbon steel 20 is manganese.

Heat treatment is a process used to alter the physical and chemical properties of low carbon steel 20. This treatment is performed to eliminate internal stresses, increase the toughness and improve the strength and ductility of the material. The heat treatment process involves heating the material to an appropriate temperature and maintaining the temperature for a certain period of time to allow the microstructure of the material to transform. In the case of low carbon steel 20, the microstructure typically transforms from an austenite (body centered cubic) structure to a ferrite (face centered cubic) structure.

The microstructure of low carbon steel 20 that has undergone heat treatment is typically dominated by ferrite and pearlite, with small amounts of pearlite, acicular ferrite, bainite and martensite present. The combination of these microstructures provides the material with excellent mechanical properties. The strength and ductility of low carbon steel 20 increase with the addition of heat treatment, making it ideal for applications that require both strength and toughness such as food processing machinery and automotive components.

Low carbon steel 20 is also highly resistant to surface wear due to its hardened surface. This property makes it a great choice for use in food processing machinery, surgical instruments, and parts exposed to corrosive environments. Low carbon steel 20 is most commonly seen in the form of sheet and plate but can also be found in bar, tube and wire products.

In summary, low carbon steel 20 (heat treatment) is a type of low carbon steel that is widely used due to its excellent mechanical properties and high surface wear resistance. Heat treatment of low carbon steel 20 increases its strength and ductility and also optimizes the microstructure, making it ideal for multiple applications.