Steel alloy and it’s usage in industry

Specifications of steel alloy

Many ordinary people think that steel is a metal. But this belief is completely wrong. Steel is actually an alloy that is made up of iron and about 2% carbon. The use of carbon in steel will change the special properties of this alloy.

Increasing the amount of carbon increases the hardness and strength of the steel sheet. On the contrary, it reduces its ductility. Steel alloy has high strength and flexibility. These features have led to the use of steel for various purposes.

Depending on the type and amount of other elements in it, mechanical properties such as hardness and ductility are also affected. Manganese, silicon, chromium, carbon, and are alloying elements with iron in the manufacture of steel.

Simple carbon and alloy steels

Steels are usually divided into two categories: alloy and carbon. Carbon steels use only carbon and other common compounds such as silicon, manganese, sulfur and phosphorus are not used. By adding some other elements to iron, other alloys ( alloy steels ) are obtained, some of which have many properties. For example, by combining chromium with iron, stainless steel or stainless steel is obtained, which has a high resistance.

What Makes Stainless Steel Stainless Steel?

Stainless steels must contain 10.5% chromium. By combining chromium with oxygen in the air, chromium oxide is produced, which forms a layer on the steel. The resulting layer destroys the connection between the metal and the air and keeps the metal healthy. Of course, the presence of other elements such as nickel and molybdenum also increase the stainlessness of steel.

Properties of steel

In plain carbon steel, there is no element other than iron and carbon. But adding chromium to it will produce stainless steel or so-called stainless steel.

As mentioned, the addition of at least 5 to 10 percent of the element chromium causes a reaction with oxygen in the air, resulting in chromium oxide as a coating in the steel alloy.

This protective layer is not visible to the naked eye and will eliminate the contact between the metal and the air and will prevent the metal from rusting. It should be noted that the use of elements such as nickel and molybdenum strengthens this layer and will increase the stainlessness of steel.

Some of the properties of stainless steels are :

• Corrosion resistance
• Heat resistance
• Long and useful life
• Attractive appearance

Steel is generally divided into two simple categories, carbon and alloy. In plain carbon steel, there is no element other than carbon and some common elements (such as silicon, manganese, sulfur and phosphorus). By adding some elements to iron, alloys are produced that have excellent properties. For example, by adding chromium to iron, stainless steel or stainless steel is obtained, which has a high resistance to various corrosions.

Types of steel

Steels are divided into three categories :

• Austiniti
• Ferriti
• martensite

Austenitic steel

Austenitic stainless steels are composed of austenitic phase. Austenite is a form of iron that absorbs more carbon than ferrite. Austenite is produced by heating ferrite to 912 ° C. At this temperature (912), ferrite changes from a centered cubic crystal structure, or bcc, to a face-centered cubic crystal structure, or fcc (face centered cubic). Cubic structures with full center faces can absorb up to 2% carbon.

When the austenite cools, the fuzzy structure returns to the ferrite state. This makes it difficult to use austenite for any application that is exposed to very high temperatures, such as smelting furnaces. One way to preserve the crystalline structure of austenite at low temperatures is to add austenite phase stabilizing elements such as nickel and manganese. For this reason, in the chemical composition of many austenitic stainless steels, these two elements are present.

Austenitic stainless steels are not hardened by heat treatment, but they can be hardened by applying mechanical work in cold working conditions. Austenitic stainless steels are widely used due to their good corrosion resistance. These steels are divided into two series, 300 series and 200 series, and the applications of 300 series are much more.

Meanwhile, 304 steel sheet is the most well-known, best-selling and most widely used alloy category among all types of stainless steels, so that it has more than 50% of the total sales of stainless steels. After this grade, the most sold and used among austenitic steels belongs to 316 steel sheet.

Nickel is one of the main alloying elements in 300 series austenitic stainless steels. Because nickel is a very expensive metal, price fluctuations have a direct impact on the price of stainless steels. The minimum nickel content in austenitic stainless steels is 8% and reaches up to 22%. For this reason, 310 refractory steel sheet with the highest amount of nickel, also has the highest price. 

Ferrite steel sheet

Ferrite stainless steels are made of ferrite crystals. These crystals are a form of iron that contains only a small amount of carbon (up to 0.025%). Ferrite can absorb a small amount of carbon due to its bcc (body centered cubic) crystal structure, which has one atom in each corner as well as in the center of the cube.

This atom in the forms of iron crystals is what gives stainless steel ferrite its magnetic properties. Ferritic stainless steels are less used due to their limited resistance to corrosion and their moderate hardness and strength. Of course, it should be noted that among all 400 series stainless steels, including ferrite and martensitic steels, 430 steel sheet has the most applications and sales.

430 stainless steel sheet is also known as steel catch sheet in the market. This steel is used in the manufacture of many household appliances such as refrigerators, stoves, kitchen utensils and…. Is used. In many cases, if the required properties are provided, it can be an alternative to 304 steel sheet and 316 steel sheet. Because grade 430 contains small amounts of nickel, less than one percent, it has a lower price than austenitic stainless steels such as 304 and 316 steel sheets. 

Martensitic steel sheet

Stainless steel martensite is formed by creating a martensite phase. Martensite has been a key element in quench steel for hundreds of years, but was officially named martensite in the 20th century after the death of metallurgical scientist Adolf Martens (1814-1950). These steels, like stainless steel ferrites, have magnetic properties.

Martensite is a form of center-filled cubic iron (bcc) that is formed by rapid cooling and quenching of austenite. If the rate of formation of martensite crystals increases, cementite does not have time to form, and it also causes carbon atoms to become abnormally trapped in crystals that normally excrete excess carbon as it cools.

Martensitic stainless steels can be heat treated and hardened. However, compared to austenitic stainless steels, their chemical resistance decreases. Martensitic steel sheet is used when the difficulty is important. Knives, for example, are an example of the use of martensitic steel sheets, the hardness of which makes the blade sharp. Among the most famous martensite grades are 410 and 420 steel sheets.

Differences between austenitic, ferritic and martensitic steels

Unlike martensitic and ferrite groups, austenitic steel sheet has no magnetic properties. These steels also show better corrosion resistance than these two groups. Another major difference between these steels is their chemical composition. So that the type and amount of alloying elements in addition to changing the mechanical, physical and chemical properties has a direct impact on the price of stainless steels.

Austenitic steels, as mentioned, contain nickel (8 to 22%). The amount of this element in the chemical composition of martensitic and ferritic steels is not significant. Therefore, austenitic stainless steels have a higher price than the two groups.

Steel sheet grades

Approximately to the number of standards used to make and the compounds used in the production of steel sheets, different types of categories are defined for it. The number of categories of steel sheets is so large that sometimes by just changing the percentage of one element, dozens of types of steel sheets can be sent to the market and a unique identity card can be issued for each one.

In this section, we review one of the most common classifications of steel sheet asdefined by ASTM ( American Society for Testing and Materials ) .

200 series steel sheet

Austinitium alloys of chromium, nickel and manganese are the main constituents of this type of steel sheet.

• 201 steel sheet :

It is austenitic type and is made by cold rolling. 201 steel alloy is actually a type of stainless steel that contains half the amount of nickel in the conventional alloy and the amount of nitrogen and manganese has increased. The price of this alloy is cheaper compared to other alloys. Steel 201 is a type of austenitic metal that has become a non-magnetic stainless steel due to the high amount of chromium and nickel in it and the small amount of carbon.

The uses of this type of alloy are :

• • Manufacture of food and pharmaceutical machinery
  • Industrial kitchen industries
  • Making all kinds of fittings
  • Furniture and decoration of office, home and store environments
  • Manufacture of steel doors and windows and tank types
  • Use in vessels carrying liquids
  • Build fences and…

• 202 steel sheet :

It is of austenitic type and is considered as a stainless steel compound. Because stainless steel 201, like stainless steel 304, is non-magnetic and very similar in appearance to grade 304, this has led manufacturers to reduce costs, maintain some properties, and at the same time without affecting the appearance, They started to produce this alloy, which, of course, left the hands of fraudulent sellers open, and caused some of them to offer Grade 201 to the customer instead of 304, and of course with the same price of 304 steel.

300 series steel sheet

• 301 steel sheet :

This sheet is very flexible and can be formed a lot. It is a chromium nickel austenitic stainless steel. This alloy is non-magnetic in annealed conditions, but becomes magnetic when cold worked. High strength and excellent corrosion resistance make type 301 stainless steel useful for various applications.

Common uses include aircraft fuselages, trailer fittings, kitchen utensils, car brakes, car wheel hoods, roofing tools, cabinets, belt conveyors, dishwashers, and subway cars. Of course, the use of stainless steel in home appliances is also undeniable.

Type 301 can be easily formed and stretched. Due to the high hardness, medium annealing can be considered necessary for separation and ductility operations. Good welding capability and high abrasion resistance are among its main features. 

• 302 steel sheet :

It has a corrosion resistance equal to 304 steel sheet, and of course it is more durable due to a little extra carbon, and it is a very strong grade that shows excellent corrosion resistance. 302 is a non-magnetic grade that cannot be hardened by heat treatment. Generally used in annealed conditions. This type of grade is considered because of its ease of construction and ductility.

• 303 steel sheet :

It has better ductility than 304 steel sheet due to excess sulfur and phosphorus. Alloy 303 is a non-magnetic austenitic stainless steel that cannot be hardened by heat treatment. Alloy 303 is specifically designed to show machining improvements. However, due to the presence of sulfur in the steel composition, it retains properties such as corrosion resistance and mechanical properties.

303 austenitic stainless steel alloy is easily machined. However, the addition of sulfur reduces the strength of 303 steel sheet compared to 304 alloy. As with other austenitic grades, the 303 alloy exhibits excellent stiffness, although it does reduce sulfur slightly. 303 alloy is often used in applications where parts are heavily machined. Some examples are: bolts, plane fittings, gears, bolts, shafts

• 304 steel sheet :

The most common type of sheet is stainless steel, the classic name of which is 18/8 steel sheet. These numbers represent the percentage of chromium and nickel in this sheet, respectively. Steel 304 is also like 201 stainless alloy, which is called non-corrosive. It will not be possible to attract magnets to this type of steel. The constituents of this steel also contain some chromium and nickel , which increases the moisture resistance of this alloy.

304 steel alloy is also used for various purposes due to its non-rust and corrosion resistance properties. Due to the high content of chromium and nickel in this grade, it is a suitable choice when making equipment for chemical processes, food and dairy and beverage industries. This grade has an excellent combination of strength, corrosion resistance and buildability.

The uses of this type of alloy are :

• • Making spoons and forks
  • Making steel kitchen sink
  • Steel profiles
  • Manufacture of valves and fittings
  • Manufacture of steel doors and windows and…

• L304 steel sheet :

The low carbon version is 304 steel sheet. It is very suitable for welding. 

• 305 steel sheet :
  

Type 305 is a chromium-nickel austenitic stainless steel with a low hardening rate due to the increased nickel content. This low degree of hardness makes this grade suitable for deep multi-stage applications that involve no annealing process. Type 305 is non-magnetic under annealing conditions and has the same corrosion resistance as 304 / 304L stainless steel.

• 308 steel sheet :

308 stainless steel usually contains about 20% chromium and an average of 11% nickel. 308 stainless steel is often used in restaurant equipment and casting equipment, chemical tanks and in the production of welding wire. 308 stainless steel is the second most widely used stainless steel

• 309 steel sheet :

works better than 304 in terms of heat resistance. 

• 310 steel sheet :

310 is an austenitic stainless steel alloy that combines excellent properties with high weldability and ductility at high temperatures. It is usually used for cases where high temperature is used.

Because of its high chromium and nickel content, it provides corrosion resistance, excellent oxidation resistance and high temperature resistance up to 2100 degrees Fahrenheit. Due to the high content of chromium and nickel, this type of grade is superior to 304 or 309 stainless steel in most environments

• 314 steel sheet :
  

Grade 314 stainless steel has features such as high temperature resistance among chrome-nickel steel series. The silicon content in this material improves oxidation and corrosion resistance. However, it becomes very brittle when left at a temperature of 649-816 for a long time. (1200-1500 degrees Fahrenheit).

• 316 steel sheet :

This stainless steel grade contains 18% chromium, 14% nickel and molybdenum. After 304 steel sheet, 316 steel sheet is the most used in various industries. These compounds increase the corrosion resistance of steel. In particular, molybdenum is used to control the corrosion zone. This type of steel can withstand temperatures up to 1600 degrees Fahrenheit.

Type 316 is used in the chemical, paper and pulp industries, for the processing and distribution of food and beverages, and in more corrosive environments. It is also used in the marine industry due to its corrosion resistance. Another high-consumption industry is 316 watchmakers. This sheet is able to withstand heat of 2000 degrees Fahrenheit and is also used to make chimney liners. 

• L316 steel sheet :

The low carbon version is 316 steel sheet. 

• 317 steel sheet :

It is made of stainless steel and has a very high resistance to chemical attack due to its significant percentage of molybdenum. In this category, the performance of this sheet is better than 304. High tensile strength, excellent stress tolerance and acceptable creep strength are other features of 317 steel sheet.

Titanium contains at least five times the amount of carbon. This additive is used to reduce or remove carbide carbon deposits from welding or high temperature exposure. Used in the aerospace industry

• 321 steel sheet :

 Similar to sheet 304 during welding, the risk of weld rot due to the addition of titanium is much lower.

• 347 steel sheet :

In highly oxidizing conditions, it has a higher corrosion resistance than 321 stainless steel. Type 347 is required for applications where alternating temperatures between 800 ºF (427 ºC)  and 1650 ºF (899 ºC)  are required or for welding in conditions that prevent welding

• 348 steel sheet :
  

Type 348 is an austenitic stainless steel with excellent intergranular corrosion resistance. This alloy is required for usages that require alternating temperatures between 800/1650 degrees (425/900 degrees Celsius)

This alloy is well resistant to corrosion of barley, food, sterilized solutions, many organic and inorganic chemicals and pigments. Due to its lack of clonimium and tantalum, type 348 stainless steel should be considered for nuclear usages

400 series steel sheet

• 405 steel sheet : has special compounds for welding. 
• 408 steel sheet : with 11% chromium and 8% nickel, has a high resistance to heat but is weak against corrosion. 
• 409 steel sheet : This sheet is one of the cheapest types of steel sheet that is mostly used for car exhaust. 
• 410 steel sheet : It has significant amounts of iron and is very resistant to abrasion and corrosion. 
• 416 steel sheet : It has high ductility and machining due to having extra sulfur. 
• 420 steel sheet : Used to make all kinds of cutlery. 
• 430 steel sheet : This sheet is used to make more decorative materials. Due to good ductility, car decorations are prepared using this sheet.
• 440 steel sheet : Produced with very high temperature. It is used in the manufacturing industry of cutlery due to high carbon. This sheet can be considered one of the hardest types of stainless steel. It is divided into different types and degrees, in each of which a special capability has been strengthened by adding compounds. 
• 446 steel sheet : Suitable for working at very high temperatures.

500 series steel sheet

They have a very high resistance to heat due to the amount of chromium.

600 series steel sheet

The classification of this series of steel sheets is according to the alloys used in them.

• 601 to 604 steel sheet : with low martensitic alloy percentage
• Steel sheets 610 to 613 : Secondary hardening steels are martensitic. 
• Steel sheets 614 to 619 : Chromed steels are methanitic. 
• Steel sheets 630 to 635 : They are metallic semi-solid stainless steels. 17% chromium and 4% nickel are the main materials used in them. 
• Steel sheets 650 to 653 : are austenitic steels reinforced by hot rolling.
• Steel sheet 660 to 665 : Manufacture of steel pipes, construction of ship plates and offshore platforms, weather-resistant steel plates, steel boiler and pressure boiler, steel pipes and steel plates used in the car are other uses. Steel sheets are in the industry.

Low carbon grades ( grade L )

 “L ” grades are used for greater corrosion resistance after welding. The letter ”  L” after the stainless steel grade number indicates low carbon. To prevent carbide deposition, the carbon level is maintained at 0.03% or less, which can lead to corrosion

Due to the temperature generated during the welding process (which can lead to carbon deposition), grade  “L” is commonly used. Typically, these stainless stainless mills to be dual certified as 304/304 L  or 316/316 L  offerings

High carbon grades ( grade  H )

“Stainless H ” grades  have a minimum carbon content of 0.04% and a maximum carbon content of 10%. Higher carbon maintains strength at high temperatures. These grades are indicated by the letters  “H” after the stainless steel grade number .

Austenitic stainless steel family

St.steel 302-S30200 : General application (base grade of austenitic group)

• St.steel 202-S20200 : Contains N and Mn to replace part of Ni
• St.steel 201-S20100 : Contains N and Mn to replace part of Ni
  • St.steel 205-S20500 : Contains N and Mn to replace part of Ni
• St.steel 302B-S30200 : Add Si to improve scaling resistance
• St.steel 301-S30100 : Reduce Cr and Ni to increase hard work
• St.steel 303-S30300 : Addition of S to improve machinability, less corrosion resistance than 302 and 304
  • St.steel 303Se-S30300 : Add Se to improve machined surfaces
• St.steel 304-S30400 : Low C to improve corrosion resistance in welded structures
  • St.steel 304L-S30403 : Further reduction C
    • St.steel 304LN : Add N to increase strength
  • St.steel 304N-S30451: Add N to increase strength
  • St.steel 308-S30800 : Contains more Cr and Ni for better welding
  • St.steel 321-S32100 : Ti increase to prevent chromium carbide deposition in welding
    • St.steel 347-S34700 : Add Nb and Ta to prevent chromium carbide deposition
    • St.steel 348-S34800 : Contains limited Ta and Co for core applications
    • St.steel 305-S30500 : Increase Ni to reduce hard work
    • St.steel 384-S38400 : Has more Ni to reduce hard work
    • St.steel 305-S30500 : Add Cu to improve cold work
• St.steel 309,309s-S30900, S30905 : Increased Cr and Ni to improve corrosion resistance and scaling at high temperatures (309s have less carbon to produce less carbide deposits)
  • St.steel 310,310s-S31000, S31008 : Increase Cr and Ni to 309 to improve corrosion resistance and flaking at high temperatures (310 s has less carbon to produce less carbide deposits)
    • St.steel 314-S31400 : Si boost for best heat resistance
• St.steel 316-S31600 : Add Mo to improve corrosion resistance
  • St.steel 316N-S31651: Add N to increase strength
  • St.steel 316F-S31620 : Add S and P to improve machining
  • St.steel 316L-S31603 : C reduction to improve corrosion resistance
    • St.steel 316LN : Decrease C and increase N to increase strength
• St.steel 317-S31700 : Contains more Cr and Mo for better corrosion resistance
• St.steel 317L-S31703 : C reduction to improve welding properties

Advantages of using steel

• Steel has a very high resistance to any type of climate, which is cold in the cold season and hot in the hot season, and one of its main characteristics is its flexibility.
• Steel, which has a very beautiful shape, the radiance and quality level of the sheets has made it famous and popular.
• One of the advantages of using steel is its high durability.
• Steel has the ability to regenerate like other metals.
• It has a very high resistance to high temperatures.

How to calculate the weight of steel sheet

Steel sheet is one of the most widely used alloys used in industry. From food and beverage related industries to industries such as oil, gas and petrochemicals that mainly use a variety of steel sheets in different dimensions and thicknesses. One of the most important points about steel sheet is calculating the weight of this alloy.

The main reason is that the most important parameter in determining the price of steel sheet, in the first step is to calculate the weight of steel sheet. This weight determination, in addition to the practical method, which is the same as weighing on a scale, also has a theoretical method that according to the product of the dimensions of the steel sheet ( thickness, length and width ) in the volumetric mass ( density ) of the steel alloy, which in some cases 7.8 and in some cases 8 is considered ( according to the grade of steel sheet ).

The formula for determining the weight of steel sheet is as follows :

 

Steel sheet weight (in kg) = length (mm) / 1000 * width (mm) / 1000 * thickness (mm) * density of steel sheet

For example : the weight of 304 steel sheet with dimensions of 2 * 1500 * 6000 miles is as follows. The density of 304 steel sheet is considered to be approximately 7.8 :

2 * 1.5 * 6 * 7.8=∼ 140 kg

summary and Conclusion

Despite the various standards and different types of steel sheets, different industries should study their technical specifications to select a suitable sample for themselves. These sheets also have different prices depending on the thickness and alloys used, and in this regard, it is better to be sure about the standards used in them before making a purchase.

The steel sheet industry is one of the largest and most powerful industries in the world, and in recent years, Asian countries have entered the field of competition in this category with their products. Therefore, you must be careful in choosing the brand of steel sheet.
Please see:

Aluminum

Zinc

Copper

Lead