What is steel material?

 

What is steel material?

A class of metallic materials. Mainly steel and cast iron. Is the most important chemical machinery material. Ferrous metal materials mainly refer to iron and steel. Most chemical machinery and equipment are made of cast iron and carbon steel.

Ferrous materials are iron and iron-based alloys (steel, cast iron and ferroalloys).

Brief description

Ferrous metal, also known as iron and steel materials, includes industrial pure iron containing more than 90% iron, iron containing 2% ~ 4% carbon, carbon steel containing less than 2% carbon, and various uses of structural steel, stainless steel, heat-resistant steel, high-temperature alloy, precision alloy, etc. Ferrous metals in a broad sense also include chromium, manganese and their alloys. Both cast iron and steel are alloys of iron and carbon, which differ in their carbon content and internal structure. Cast iron is an iron-carbon alloy with carbon content greater than 2%, and steel is an iron-carbon alloy with carbon content less than 2%. They are the most widely used metal materials in industry and play an important role in national economy.

Industrial steel according to the chemical composition can be divided into carbon steel (carbon steel, carbon steel) and alloy steel (alloy steel) two categories. Carbon steel is an iron-carbon alloy with carbon content less than 2.11%. In addition to iron and carbon, steel also contains a small amount of manganese, silicon, sulfur, phosphorus and other impurities. Carbon steel is widely used because of its low price, easy to obtain, easy to process and good mechanical properties. However, with the development of modern industry and science and technology, the mechanical properties and physical and chemical properties of steel put forward higher requirements, thus the development of alloy steel. The so-called alloy steel, is in order to get or improve some properties, add an appropriate amount of one or more alloying elements on the basis of carbon steel and get multiple iron based alloy.

Cast iron is an iron - carbon alloy with carbon content greater than 2.11%. In addition to carbon, cast iron also contains more Si, Mn and other impurity elements. In order to improve the mechanical properties of cast iron, a certain amount of alloy elements can be added to form alloy cast iron. Compared with steel, cast iron smelting is simple, low cost, although the strength, plasticity and toughness is low, but has excellent casting performance, high friction and wear resistance, good shock resistance and machinability and notch sensitivity low series of advantages. Cast iron is widely used in industrial sectors such as machine building, metallurgy, petrochemical, transportation, construction and national defense. Cast iron and steel have the same matrix. The metal matrix of cast iron mainly includes ferrite, pearlite and ferrite plus pearlite. Due to the different chemical composition of iron liquefaction, cooling rate and treatment method of liquid iron, so in addition to a small amount of carbon in cast iron soluble in ferrite, the rest of the carbon can form graphite, also can form cementite.

Species introduction

1.steel

Steel is divided into two types: carbon steel and alloy steel.

(1) Carbon steel. Iron-carbon alloys with carbon content less than 2.11% and a small amount of impurities are collectively referred to as carbon steel. Carbon steel has been widely used in automobile industry because of its low price and good technology.

Carbon steel commonly used in automobile manufacturing industry mainly includes carbon structural steel, high quality carbon structural steel and cast steel.

(2) alloy steel. In order to improve the performance of steel, steel is made by adding some alloying elements. Commonly added alloying elements are titanium, niobium, tungsten, molybdenum, chromium, manganese, aluminum, drill, silicon, boron, nitrogen and rare earth elements.

There are many kinds of alloy steel, alloy structural steel and rolling bearing steel are commonly used in the automobile industry. Rolling bearing steel is a special steel used to manufacture rolling bearing rolling body and inner and outer ring. Alloy structural steel can be divided into low alloy high strength structural steel, alloy carburizing steel, alloy tempered steel and alloy spring steel according to different composition and use.

2.Cast iron

The iron carbon alloy with carbon content greater than 2.11% is called cast iron. Its strength, plasticity and toughness are poor, but it has good casting property, machinability and wear reduction, and the production equipment and process is simple, cheap, so it has been widely used in the automobile industry.

According to the different graphite crystal morphology of cast iron, cast iron can be divided into three categories: gray cast iron, malleable cast iron, nodular cast iron.

(1) gray cast iron. The graphite in the cast iron structure is flake crystal, and the mechanical properties are not high, but the production process is simple, the cutting performance is good, the price is low, and the wear resistance is good, so it is widely used.

(2) malleable cast iron. The graphite form of cast iron is flocculent, its mechanical properties are higher than ordinary gray cast iron, but the production process is more complex, the cost is higher, generally used to manufacture important small castings.