High quality carbon structural steels are hot rolled steel sheets and strip that are divided into two groups according to composition. The general group of high quality carbon structural steels is composed of ferrite, pearlite, martensite and bainite according to their main phases. GB 710-91 states that the chemical composition (in percentage by mass) of the high quality carbon structural steels is as follows:
C Si Mn ≤0.22 ≤0.35 ≤1.4
High quality carbon structural steels are characterized by their excellent mechanical performance, good formability and joinability, good fatigue strength and high strength, combined with good welding and machining property. High quality carbon structural steels are widely used in a variety of structural applications, from bridges and buildings to the manufacture of machines and tools. GB 710-91 is applicable to all grades of high quality carbon structural steels and its requirements include tensile strength, yield strength, percentage elongation, chemical composition, welding properties and surface quality.
High quality carbon structural steels can be divided into two categories according to their chemical composition: C ≥ 0.25% Si < 0.25% low carbon steel and C < 0.25% Si < 0.35% medium carbon steel. Both categories can be divided into four types corresponding to different mechanical properties.
The main production processes of high quality carbon structural steels are hot rolling, cold rolling and hot extrusion. Hot rolling is used to reduce the thickness of the steel sheet, while cold rolling is used to increase the strength of the steel sheet. Hot extrusion is used to extrude the steel sheet into complex shapes with a die.
The hot rolled steel sheet and strip of high quality carbon structural steels are extensively used in many industries. It can be used for shipbuilding, bridge construction, high-pressure vessel manufacturing, boiler making and motor vehicles. In addition, it can also be used for agricultural machinery, ball bearing cages and other machinery parts.
To ensure that high quality carbon structural steels meet required standards, the mechanical properties of the steel should be tested. Generally, the mechanical properties of high quality carbon structural steels are tested by means of tensile testing and impact testing. The tests are usually used to evaluate the strength, ductility, hardness and toughness of steel components.
In conclusion, high quality carbon structural steels are widely used in many industrial applications. They offer excellent mechanical properties, formability, weldability and corrosion resistance. GB 710-91 states the requirements of the chemical composition, tensile strength, yield strength, percentage elongation and surface quality for high quality carbon structural steels. Additionally, quality assurance for high quality carbon structural steels can be achieved through mechanical property testing.
