Iron and steel basic knowledge combing (1)

In modern industrial society,steel,as a fundamental material,holds an irreplaceable position.Whether it is the construction of high-rise buildings,the erection of bridges,or the manufacture of cars and planes,steel plays a crucial role.However,despite its ubiquity in our daily lives,many people have little knowledge of the basic facts about steel.To help readers better understand this fundamental material,this article will provide an overview of some basic facts about steel.

One,Definition and Classification of Steel

1.1 Definition of Steel

Steel is an alloy made up of iron,carbon,and small amounts of other elements.Iron(Fe)is the main component of steel,typically accounting for more than 98%of the total mass.Carbon(C)is the most important alloying element in steel,and by adjusting the carbon content,different types and properties of steel materials can be obtained.

1.2 Classification of Steel

Steel can be classified according to different standards,and the following are some common ways of classification:

By chemical composition:it can be divided into carbon steel and alloy steel.Carbon steel only contains iron and carbon,while alloy steel adds other alloy elements such as chromium(Cr),nickel(Ni),manganese(Mn)to improve the mechanical properties and corrosion resistance of steel.

By application:it can be divided into structural steel,tool steel,stainless steel,heat-resistant steel,and electrical steel,etc.Each type of steel has its specific application area,such as structural steel is mainly used for construction and bridges,while stainless steel is widely used in kitchen utensils and chemical equipment due to its corrosion resistance.

By microstructure:it can be divided into ferritic steel,austenitic steel,pearlitic steel,and bainitic steel,etc.These classifications are mainly based on the microscopic internal structure of steel,and different microstructures will affect the mechanical properties and processing properties of steel.

By production process:it can be divided into hot-rolled steel,cold-rolled steel,forged steel,and cast steel,etc.Different production processes will affect the microstructure and properties of steel,and are suitable for different application scenarios.

Two.Steel production process

2.1 Iron smelting process

Iron smelting is the process of reducing iron ore to iron.The main methods of iron smelting are two:blast furnace smelting and direct reduction of iron.

Blast Furnace Ironmaking:The blast furnace is the main equipment for ironmaking,and its basic principle is to use coke as a reducing agent to remove oxygen from iron ore at high temperatures,producing pig iron.The main raw materials for blast furnace ironmaking include iron ore,coke,and fluxing agents(such as limestone).

Direct Reduced Iron:Direct reduced iron is an ironmaking method that does not use a blast furnace.Its basic principle is to reduce iron ore using reducing gases(such as carbon monoxide)at high temperatures to produce sponge iron.Direct reduced iron production is relatively environmentally friendly,but the cost is higher.

Steelmaking is the process of removing impurities from pig iron and adjusting its composition and properties.The main methods of steelmaking are two:blast furnace steelmaking and electric furnace steelmaking.

Basic Principle of Converter Steelmaking:Converter steelmaking is one of the most commonly used methods of steelmaking,whose basic principle is to oxidize impurities in pig iron such as silicon,manganese,and phosphorus into slag using oxygen,and at the same time adjust the carbon content to obtain steel water that meets the required specifications.Converter steelmaking has the advantages of high production efficiency and low cost.

Basic Principle of Electric Furnace Steelmaking:Electric furnace steelmaking is a process of melting waste steel,iron alloys,etc.using electric energy and adjusting the composition by adding deoxidizing agents and alloying elements.Electric furnace steelmaking is suitable for producing small batches of high-alloy steel and special steel,and has the advantages of high flexibility and good environmental protection.

The rolling of steel involves the plastic deformation of steel water or billets through rolling mills to obtain the desired shape and size.The common rolling methods are hot rolling and cold rolling.

Hot Rolling:Hot rolling is a rolling process that is carried out at high temperatures,which has the advantage of high production efficiency and low energy consumption,but the surface quality and dimensional accuracy of the rolled steel are relatively lower.Hot rolled steel is widely used in construction,bridges,machinery and other fields.

Cold Rolling:Cold rolling is a rolling process carried out at ambient temperature,which has the advantage of good surface quality and high dimensional accuracy of the rolled steel,but high energy consumption and low production efficiency.Cold rolled steel is mainly used in the fields of automobiles,household appliances,precision instruments and so on.

III.Steel Performance and Testing

3.1 Physical Properties of Steel

The physical properties of steel primarily include density,melting point,thermal conductivity,and electrical conductivity.These properties determine the potential for steel's application in different environments.For example,the high density of steel makes it have good load-bearing capacity,while its good thermal conductivity enables it to quickly transfer heat during heating and cooling processes.

3.2 Mechanical Properties of Steel

The mechanical properties of steel refer to its performance under load,including strength,hardness,toughness,and ductility.These properties are crucial factors in determining whether a particular steel material can meet the requirements of a specific application.

Strength:Strength refers to the ability of steel to resist deformation and fracture under load.Common strength indicators include tensile strength and yield strength.

Hardness:Hardness refers to the ability of steel to resist local indentation and scratching.Common hardness testing methods include Brinell hardness,Rockwell hardness,and Vickers hardness,among others.

Toughness:Toughness refers to the ability of steel to absorb energy under load.Toughness is typically evaluated through impact tests.Steel materials with good toughness are less likely to break under impact.

Ductility:Ductility refers to the ability of steel to undergo plastic deformation without breaking under load.Common ductility indicators include elongation and reduction in area.

The chemical properties of steel mainly include corrosion resistance and oxidation resistance.These properties determine the service life of steel in specific environments.For example,stainless steel is widely used in chemical and food processing industries due to its excellent corrosion resistance.

3.4 Testing Methods for Steel

To ensure the quality of steel materials,various performance tests are needed.Common testing methods include tensile tests,impact tests,hardness tests,and metallographic analysis.

Tensile Test:The tensile test is one of the main methods for evaluating the strength and ductility of steel materials.Through the tensile test,important indicators such as tensile strength,yield strength,and elongation can be obtained.

Impact Test:The impact test is one of the main methods for evaluating the toughness of steel materials.Through the impact test,the energy absorbed by the material when subjected to impact can be measured,thereby evaluating its toughness level.

Hardness Test:The hardness test is one of the main methods for evaluating the hardness of steel materials.Common hardness testing methods include Brinell hardness,Rockwell hardness,and Vickers hardness,each with its own specific range of application and precision requirements.

Metallurgical Analysis:Metallurgical analysis is a method for evaluating the performance of steel materials by observing and analyzing their microstructures.Through metallurgical analysis,information such as grain size,distribution,and phase composition can be obtained,providing important basis for performance evaluation.4.Conclusion

Steel is a fundamental material that plays a vital role in modern industrial society.By learning and understanding the basics of steel,we can better understand this material and fully utilize its performance advantages in practical applications.This article provides a brief overview of the basic knowledge of steel.We hope it can help you build a basic understanding of steel.Future articles will delve deeper into more knowledge about steel,so stay tuned.