Introduction
Carbon Steels are the most common and popular steel alloys used extensively in manufacturing today. With the advancement in metallurgy, there has been a great emphasis on the development of steel materials with improved properties such as corrosion resistance, strength, and thermal efficiency, thus increasing their scope of applications. As carbon is an important element in steel formation, the introduction of carbon in steel alloys, through a process known as carburization, has been an effective engineering tool in developing stronger, corrosion-resistant and temperature efficient steel products. This paper presents the new developments in steel carburization processes.
Historical Perspective
Steel carburization has been used in the production of high-quality steel for more than a hundred years. The earliest practices of steel carburization used coal and coke as the sources for carbon for steels plates. Heat treatment processes were done in furnaces, using alumina boat or graphite crucible containers. Most of the early processes had difficulties in controlling the temperature of carburization, affecting the quality of the produced steel. With the advances in metallurgy, furnaces and other heating techniques, steel carburization techniques have made an immense development over the years.
Current Developments
Today, a variety of carburization techniques are used to introduce carbon in a steel alloy. Some of the recent developments are discussed in this paper.
Gaseous Carburization
Gaseous carburization is the process of introducing carbon in steel alloys using gaseous carbon sources. In this process, carbon containing gases are exposed to steels in furnace at controlled temperature and pressure. These gases diffuse through the surface layers of the steel, introducing carbon in the alloy, thus increasing the steel’s strength, corrosion resistance and temperature efficiency. This method is used for producing both ferritic and austenitic steel alloys.
Laser Carburization
Laser carburization is one of the recent developments in the steel carburization process. In this method, carbon-containing gases are introduced to steels, exposing them to a focused laser beam. The laser beam allows precise control of the temperature and uniform diffusion of the gases into the steel. This method is mostly used in producing structural steel alloys due to its advantageous surface finish and precise control of carburization parameters.
Chemical Vapour Deposition
The Chemical Vapour Deposition process is a unique approach to carburization. This process involves heating a steel surface and introducing a carbon-containing gas, either directly or by chemical reaction, which deposits carbon onto the steel surface. The carbon deposition forms a protective carbon layer on the steel surface, thus providing superior corrosion and wear resistance as well increasing the temperature efficiency of the steel alloys. This method has proven to be an effective process for carburizing steels for critical automotive applications.
Conclusion
Steel carburization has been an effective manufacturing tool for more than a hundred years. However, with the advances in metallurgy and heat treatment processes, there has been a significant development in the steel carburization techniques. Today, there are different methods of introducing carbon into steel alloys such as Gaseous, Laser and Chemical Vapour Deposition Carburization, which have proven to provide superior properties to the steel alloys being used in a variety of applications.
