subject: Case Hardening: A boon of technology [print this page] Case Hardening: A boon of technology Case Hardening: A boon of technology
Science has evolved to a great extent. Consequently we are gifted with a variety of technologies, which work towards improving the quality of the basic requirements of our lives. Metals form an important part of our lives. From utensils to big furnaces in the industries, metals are required almost in every aspect of life. Among the extensive variety of metals, steel and steel alloys are some of the most commonly used. So, it is necessary to make these metals strong and sturdy so that they have high level of toleration.
Case hardening is a process by which the surface of a metal is hardened. The process is also known as surface hardening. It is done to produce a robust water resistant surface over the tough and durable core of the metal. The types of case hardening that are popularly done are carburising, cyaniding, and nitriding. The process is usually ideal for low carbon steel. It is done to make steel water-resistant and sturdier. High carbon steel is not much suitable for this treatment and it causes brittleness to the internal part of the metal.
The different types of case hardening are Carburising, Nitriding and Flame hardening. The primary aim of case hardening is to make the steel more strong and durable. This process of heat treatment is widely used for large-scale industrial purpose. The process of carburising can be defined as a method in which the carbon-content of the external layer of steel is increased. Increased carbon content makes the outer layer of the steel tough and increases its longevity. But the internal part of the metal remains soft and flexible.
Steel can be carburised in two different ways. It can be heated in a furnace that is filled with carbon monoxide or it can be put in a container with charcoal or a similar carbon-rich material and then the container can be heated in a furnace. The previous method is more popular of the two and is almost universally used nowadays.
Nitriding is probably the most effective way of case hardening and produces the hardest surfaces in the steel. In this process the separate parts are pre-heated and tempered before treating in a furnace. The furnace is filled with ammonia gas and quenching is not required. Objects like engine parts, gears, cylinder sleeves, camshafts, and others, which are used in highly heated areas and go through immense wear and tear, are prepared using this technique.
Flame ardening is somewhat different from the other two methods. In this process, the metal is exposed to an oxyacetylene torch flame, which immediately heats up the outer layer of the metal. The temperature is allowed to reach the critical point at which juncture the metal is quenched with water. This process immediately makes the surface of steel hard but retains the soft core. There is a clear disadvantage in this process because there is no clear way of recording the temperatures of the metal surface. The torches heat up the metal briskly and a close watch has to be maintained to determine the temperature.
Flame hardening can be done manually as well. The automatic method produce consistent results and is used more popularly. There are four types of automatic flame hardening namely flame hardening, progressive flame hardening, spin hardening, and combination hardening.
In a nutshell case hardening is widely practiced across the world for its amazing effects. It invests steel and steel alloys with an exclusive quality. Products made out of case hardening steel are more durable, and can be used for large-scale industrial purpose.
