What is the Difference Between Steel and Stainless Steel

Steel is one of the basic and most produced materials in the world that represents an entire industry with an annual production of 1.3 billion tons a year. Steel is a major material that is used for the construction of many architectural materials. Other than that, the steel has wide application areas from aerospace to kitchenware. There are various categories and subcategories of steel depending on the diverse variety of qualities and characteristics of a particular composition. For a particular build, the selection of steel varies. The primary factors involved in the variation of the steel types are the properties like strength, ductility, hardness, aesthetics and cost. Thus if a proper steel type can be selected according to the scope of work, it definitely balances the cost and benefits of the project.

A vast range of metal alloys is described under the category “steel” as there are a hundred specific grades of steel available in the market. But the steel can majorly be classified into two categories, namely, stainless steel and carbon steel.  The two basic ingredients of both carbon and stainless steel, that is, carbon and iron are the same. The difference can be seen in the composition of the two alloys. The alloy content in the carbon steel is less than 10.2% whereas the chromium content in the stainless steel is 10.5% or even more. Due to the difference in alloy content, there is a difference in the physical properties of carbon steel and stainless steel. They both possess distinctive physical properties for the same reason. This article deals with the answer to the most commonly asked question “what is the difference between steel and stainless steel”. 

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Carbon Steel and Stainless Steel

Carbon Steel: Carbon steel is composed of carbon that is present in the 0.2 to 2% in alloy. The definition of carbon steel primarily includes alloy steel that makes up to 10.5% of the alloy content. Even with the presence of very little percentage of carbon, that is, as low as 0.2%, there is a huge variation that is reflected in the physical properties of the different grades of carbon steel, specifically, in the hardness level.

Usually, when carbon steel is being referred to it is mostly referring to the hard carbon steel that is mostly used in knives and other tools. As the hardness of the high carbon content in carbon steel is very high thus its high carbon content carbon steel tools are generally abrasion-resistant and retain shape. A huge amount of force is required to deform the carbon steel as it is capable of withstanding a huge amount of force. But like all other hard metals, carbon steel is also brittle in nature. Thus if given an extremely high tensile stress, the caron steel tends to crack or break rather than bend. The high ductility, low cost of production and easy manufacturing are the reasons for preferring low carbon steel more than the production of high carbon steel.  The low carbon content in low carbon steel makes it ductile. Hence, under extreme tensile force, it bends or deforms rather than cracks. This makes welding easy and is suitable for many machinery parts. Carbon steel is mostly used in fixtures, automobile body parts, steel plates and seamless tubes. 

Stainless steel: stainless steel is basically a steel alloy that has a minimum of 11.5% chromium content by weight. The stainless steel does not rust or stain easily like other steel but it is not completely stained proof. Though it is considered as corrosion-resistant steel in the aviation industry, its grade and alloy type are not detailed. As per the industrial or other fields of application that the stainless steel will be subjected to for a lifetime, its various surface grades and finishes are designed to suit the kind of environment in the various application fields. The common application of stainless steel is in cutlery and kitchen utensils and in the straps of various watches. 

The basic difference between carbon steel and stainless steel is the amount of chromium content in both of them. As the layer of carbon steel has an active layer of iron that results in acceleration of corrosion as more and more film of iron converts into iron oxide when exposed to the atmosphere. But in stainless steel, a sufficient amount of chromium is present so that the passive chromium oxide film that develops when the stainless steel is exposed to the atmosphere, acts as a protective layer for the iron and does not allow it to get oxidized inducing corrosion.

Difference Between Steel and Stainless Steel

Steel and stainless steel are both metals and are the materials that are commonly used in various commercial as well as consumer products around the world. The difference between steel and stainless steel arises on the basis of certain physical properties, namely, strength, hardness, ductility, cost etc that varies in both grades. The difference between steel and stainless steel is listed below:-

1. Steel is an alloy that is made by adding carbon to the iron, which makes the iron hard. This adding of carbon to iron makes mild steel or carbon steel. This form of steel has a low melting point as the carbon content in it is very high. However, due to the high chromium content in stainless steel, the chromium forms a thin layer on the surface of the steel that prevents it from staining. It is also ductile and has a lower melting point as compared to stainless steel.

2. Steel is usually prepared by adding carbon to the iron. But as carbon only increases the hardness thus under high tensile stress, the steel tends to break. Also, when the surface of the iron found in mild or carbon steel is exposed to the atmosphere, the layer of iron converts to iron oxide that results in corrosion. But stainless steel is made by adding chromium, molybdenum, nickel and nitrogen. Thus the thin layer of chromium conversion to chromium oxide acts as a protective layer and does not allow the iron to corrode. Thus the stainless steel does not rust easily.  

3. Stainless steel is malleable and ductile in nature than carbon steel. It is because the carbon content in the carbon steel is more than that of the stainless steel. The percentage of carbon present in the carbon steel or mild steel provides it with much more hardness than stainless steel.

Carbon Steel vs Stainless Steel knives 

 Points of Carbon steel vs stainless steel knives are as follows:-

1. Most of the home chefs prefer stainless steel knives while most of the professional chefs prefer high-carbon steel knives.

2. Stainless steel knives are more readily available in the market for common consumers. It is because stainless steel, even being hard on the surface, is usually very malleable and ductile in nature. It bends easily but doesn’t crack. Thus it can be thrown on marbles, or can be put into the dishwasher. Even after being subjected to high pressure, they do not break because they possess high strength.

3. As in the household purpose, the sharp and precise cutting is not required in a day to day life, thus the stainless steel knives are preferred because of their ability to prevent the knife blades from rusting. The professionals prefer carbon steel blades as they have a much higher strength as compared to stainless steel knives that are used in households. Therefore, it gives high precision while cutting tough surfaces. 

4. When the sharp precision for cutting tough irregular surfaces is not required regularly in household, stainless steel is preferred as the resistance from rusting will increase the sharpness of the edge and will also increase its shelf life. But maintaining the carbon steel blades of a knife is a very crucial process where it needs to be oiled before wrapping up the work to prevent the blades from rusting. Also, it needs to be washed in high acidic or salty conditions. In a gap of a period, it needs to be edged against some stone. Thus it makes the maintenance of carbon steel much lengthy and tedious than the stainless steel knives in households.

Properties of Stainless Steel

The properties of stainless steel are as follows:-

1. Magnetic Properties: usually half of the stainless steel grade that contains both chromium and nickel are non-magnetic in nature. There are 300 such grades of stainless steel. Whereas the stainless steel that just contains chromium has magnetic properties as chromium and iron both have magnetic properties. There are 400 such grades. 

2. Appearance: carbon steel is dull and matte in its appearance whereas stainless steel is glossy in nature due to the presence of chromium. It is attractive in its natural state before it is even painted or polished.

3. Ductile: stainless steel is more malleable and ductile but carbon steel is more durable and the distribution of head is also more uniform as compared to stainless steel. Stainless steel has low thermal conductivity.

4. Strength: carbon steel is very tough and strong in built. Thus it is used in many motors and various other electrical appliances because of its magnetic properties. Welding of carbon steel is much easier than stainless steel. 

5. Stainless Steel vs Mild Steel Weight: Mild steel has less weight as compared to stainless steel. As stainless steel has hardening properties thus it has less occupancy and possesses more weight. Therefore, it becomes very difficult to handle it in the manufacturing process.