Carbon: The main ingredient that makes up the strength of steel. As the carbon content improves, the strength of the steel increases, but the plasticity, resistance, cold-bending, weldability, and rust resistance of a steel can be reduced. In particular, impact resistance at low temperatures is also reduced. Manganese and Silicon: The beneficial elements in steel are deoxidizers that can increase strength without excessively decreasing plasticity and impact resistance. Vanadium, niobium, titanium: The alloying elements in steel can not only improve the strength of steel, but also maintain excellent plasticity and resistance. Aluminium: Strong deoxidizer, using aluminum to make up for deoxidation, can further reduce harmful oxides in steel. Chromium and nickel: Alloy elements that improve the strength of steel. Sulfur and phosphorus: Impurities that remain in steel during exercise, harmful elements. They reduce the plasticity, resistance, weldability and fatigue strength of steel. Sulfur can make steel "hot and brittle," and phosphorus makes steel "cold and brittle." “Hot and brittle”: Sulfur can generate easily melted iron sulfide. When the temperature is 800-1000°C, the steel is cracked and brittle. "Cold and brittle": At low temperatures, phosphorus makes the impact resistance of steel significantly reduced. Oxygen and Nitrogen: Harmful impurities in steel. Oxygen can make steel hot and brittle, and nitrogen can make steel cold and brittle.
The impact of metallurgical defects
Common metallurgical defects include segregation, non-metallic inclusions, pores, cracks, delamination, etc., all of which can degrade the function of the steel.
Hardening of steel
Cold drawing, cold bending, punching, mechanical shearing and other cold processing make the steel plastic plastic deformation, and then improve the steel's flexion point, together with the steel's plasticity and patience, this kind of representation is known as cold hardening or strain hardening.
Steel is sensitive to temperature, and both temperature rise and fall change the function of the steel. In contrast, the low-temperature function of steel is more important.
At the positive temperature scale, the general trend is to follow the increase in temperature, the strength of the steel decreases, and the deformation increases. There is no significant change in the function of the steel within about 200°C, and the strength (yield strength and tensile strength) drastically drop between 430°C and 540°C; the strength is so low at 600°C that it cannot bear the load. In addition, there is a blue-brittle appearance near 250°C and a creep appearance at about 260-320°C.
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