Iron, steel, and cast iron are three widely used materials that make many tools. There are many differences between them and Many people may confuse these three substances, but we must say that they are not the same in any way. Cast iron and steel are iron-based alloys, the only difference being the amount of carbon used in each. If you pay attention, a lot of kitchen utensils are made of cast iron. Cast iron is versatile, affordable, and virtually indestructible for everything. The main difference between steel and cast iron is their carbon content. Cast iron contains more than 2% carbon, while many steel alloys contain less than 1% carbon. Before we discuss the difference between steel and cast iron; it is better to look at the common properties of both metals: Common characteristics of steel and cast iron materials
- hardships
- strength/strength
- plasticity
- Toughness (toughness is a combination of ductility and strength)
You might think that cast iron is made of pure iron, but it's not! Cast iron is actually an alloy of iron and carbon, just like steel; the difference is that cast iron has a higher carbon content. While steel need not contain more than 2% carbon, cast iron typically contains 2% to 3.5% carbon. Silicon is another alloying element found in cast iron with a purity of about 1-3% by weight. The presence of these various elements affects the color and quality of the cast iron produced. The carbon content makes cast iron more brittle than steel. Since cast iron is a poor conductor, it retains heat for a long time. There are different types of cast iron and we will discuss each of them below: 
gray cast iron
The shrinkage rate and porosity of gray cast iron is small. This cast iron is the most widely used type of cast iron based on weight; it has high thermal conductivity and is ideal for making cookware. This cast iron is softer than white cast iron, while its material is hard and brittle. Gray cast iron is commonly used to make the following items:
- car base
- engine block
- motor housing
- cast iron pipe
- gear
hard cast iron The process of making hard cast iron is to heat the cast iron and then rapidly cool its outer surface; this makes the surface of the cast iron white and its core gray. Hard cast iron is, as the name suggests, very resistant, wears later, and is often used to make pipes under bridges. soft cast iron Soft cast iron is often used to make small appliances such as door and window fittings, locks, keys, and even faucets. To increase the hammering of cast iron and give it more resistance, white and semi-gray cast iron castings are heated with some iron ore fins, causing some of the carbon in it to lose in the process, burning and softening. 
white cast iron The manufacturing process of white cast iron is how it is usually used to make small tools. White cast iron is produced by high-speed cooling of pig iron. It is white because its carbon does not turn to graphite on rapid cooling and the color remains bright (silvery white). One thing worth noting here is that white cast iron is brittle in many applications, it has a very low silicon content and its material is somewhat hard and brittle. What is steel? Steel is a ferrous alloy consisting mainly of iron and carbon. Many people think that steel is a metal, but it is not. Although it exhibits properties similar to metals, it is technically classified as an alloy. Steel, like cast iron, is composed of an alloy of iron and carbon, but it contains less than 2% carbon. Stainless steel contains 1.2% carbon (and chromium to prevent corrosion). Carbon steel is opaque, although stainless steel looks a bit shiny. Carbon steel is much harder than stainless steel (usually suitable for making sharp knives), but it will corrode and rust, while stainless steel will not. The most general classification of steel is based on its carbon content as follows: mild steel The carbon content of mild steel is about 0.2%. Typically, mild steel is used to make bolts and nuts, barbed wire, pipes, steel plates, and even steel beams. 
Medium steel The percentage of carbon in medium steel is between 0.6-0.2%. Sinosteel is often used to make rails, boilers, and even machinery. hard steel The percentage of carbon in hard steel is higher than in mild and medium steel. The carbon content of this type of steel is around 1.5-0.6%. Hard steel is used to make tools, drills, springs, cutlery, etc. Sectional steel is an important member of today's structures. They are known as the most important building materials due to their properties such as high resistance and ductility. The following are the main properties of steel:
- thermal expansion
- Malleability
- connection
- mechanical resistance
It is worth noting that the mechanical properties of steel can be changed under different conditions by using different heat and cold treatments. The cooling of steel can be done slowly in water, oil or in air using a cooling device. Comparing cast iron and steel should be based on several factors. As you know, heat treatment and alloying can change the properties of metals to a great extent. In order to buy one of these two items, it is always best to know each of their features and characteristics. You can tell the difference between cast iron and steel more quickly by knowing the following: Look at the surface of two metals: it is easy to distinguish iron, steel and cast iron from the appearance! Ferrous metal surfaces are dark gray and shiny; cast iron surfaces are dull, cloudy and colored. 
Molten metal color: Steel and cast iron change color when melted. Knowing this, you can easily tell them apart. If the color of the molten metal is red, the metal is cast iron. On the other hand, if the color of the molten metal is white, it is iron. Chip test: Cast iron is a brittle metal. So its fries are crispy and crunchy. If a lathe or milling machine is available, we can machine part of the metal sample. If the chips are discontinuous, the metal is cast iron, and if the chips are continuous, it is iron. A lathe or mill is not required to perform this test. This test can also be done with a sharp pen. If the thin layer is removed from the metal, the strip is removed, the ferrous metal is removed, if the very fine chips are removed. The metal is cast iron. Alloys used: Steel must contain at least 50% iron and one or more other alloying elements. The most commonly used alloys in steel include carbon, manganese, silicon, nickel, chromium, molybdenum, titanium, and even aluminum. Melting point: The melting point of cast iron is lower than that of iron. Brittleness: Cast iron is more susceptible to corrosion than iron and is very dry and inflexible even compared to steel and iron. Cost: Remember that cast iron costs less than steel, but steel is more expensive and usually comes in different grades. Fracture: Another difference between iron, steel and cast iron is that cast iron is prone to fracture, creating cracks at impurities; whose steel is not easy to break and is flexible. 
difference between steel and iron
Steel is the most widely used material in all walks of life, especially in construction. Iron ore is converted into steel through various processes and used. Iron ore is one of the most important and abundant natural resources. In the past, iron ore was used as raw material, but today this valuable material is used as iron, steel, cast iron, etc. In fact, iron, steel and cast iron are all derivatives of iron ore. The Iron Age goes back many years, around 1400 years before Christ. Some of the works that remain in Armenia today from that time are a good testimony to this. Iron is the most widely used metal in the world, mainly because of its reasonable price and high strength. As such, almost all structures in the world are built using iron tools and parts made from iron derivatives. The strength and quality of iron depends on its purity. Since iron ore contains impurities, the purity of the final product and how and by what process it is purified is very important. In fact, when impurities are separated from iron ore and additives are added, they form different alloys. Simply put, an alloy is a combination of a metal with another material, which can be a ferrous or non-ferrous metal. For example, when iron is smelted, by removing sulfur and phosphorus, the end product becomes cast iron. Likewise, steel is an alloy composed of iron and carbon. Ferrous metal is produced only from iron ore. Therefore, one of the differences between iron and steel is the presence of carbon in its constituents. Cast iron is an iron alloy with a carbon content of 2.11 to 4.5%. 
Rebar, beams and other building parts are made of steel. The above steels are made from iron ore; there are different types of steel used to make mild steel, click on the link to learn more about mild steel. Steel is a metal composed of iron, which contains two thousandths to two percent carbon. This variable carbon content in the steel results in different strengths of the final product; that is, the higher the carbon content of the steel, the stronger it will be. As the strength of steel increases, its weldability decreases. These properties lead to different uses of steel in different situations. Therefore, steel, this widely used metal, must be made with the right amount of carbon to have good electrical resistance and better flexibility and weldability. The main structural difference between steel and iron is their carbon content. Pig iron has a much lower carbon content, while steel has a significantly higher carbon content than iron. The maximum carbon content in steel can be 2% by weight. Adding other elements to the steel production process changes the properties of the final product. For example, adding chromium to steel can improve its rust resistance, or nickel can increase the steel's strength. 
rust free Steel has different properties in structure. The first difference between steel and steel is their ability to resist corrosion. Steel has anti-corrosion properties, while iron reacts with oxygen and water in the sense of oxidation, called iron oxide. strength Another difference between steels is their strength. Steel is much stronger than iron. This strength is mainly due to its higher carbon content, and then other elements such as nickel are added, which play an important role in increasing the strength. The use of steel in all walks of life is based on its strength. Carbon content is divided into three groups: low carbon steel, medium carbon steel and high carbon steel. The presence of silicon in steel is also another difference between steel and iron. Steel containing silicon increases its tensile strength. Although iron does not have this ability like steel. Of course, the addition of elements such as manganese and chromium is also very effective in increasing this property. These two properties make steel the best material for construction. plasticity Steel is very ductile and becomes very strong when stabilized; if iron is not as ductile as steel. The difference between iron and steel is striking. Due to the high carbon content, steel is less ductile and harder. When the carbon content of steel is reduced, it becomes softer and more ductile, but it also loses its strength and is no longer suitable for building strong structures. 
melting point The higher the carbon content of steel, the lower its melting temperature and the more brittle it becomes. Unlike steel, iron has a higher melting temperature and is less brittle due to the lack of carbon. Solderability Mild steel is not as strong as the other two groups, but it is one of the best choices for the automotive industry because of its high weldability. Medium carbon steel has poor heat resistance but improved strength, so this steel is mostly used to make gears, guides, and similar structures. Finally, high carbon steel has the strongest strength and is used to make saws, springs, and blades. This steel is not a good choice for welding and brazing.