The influence of common chemical elements on the properties of metal materials

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The influence of common chemical elements on the properties of metal materials 1. Influence on the properties of steel (1) The higher the carbon content, the greater the hardness and wear resistance of the steel, but its plasticity and toughness decrease. (2) Sulfur is a harmful impurity in steel; steel with a high sulfur content tends to crack easily during pressure processing at high temperatures, a phenomenon commonly known as hot brittleness. (3) Phosphorus can significantly reduce the plasticity and toughness of steel, with the effect being more severe at low temperatures; this phenomenon is known as cold brittleness. In high-quality steel, the contents of sulfur and phosphorus must be strictly controlled. On the other hand, when low-carbon steel contains higher levels of sulfur and phosphorus, it makes the chips easier to break during cutting, which is beneficial for improving the machinability of the steel. (4) Manganese can increase the strength of steel, eliminate or reduce the adverse effects of sulfur, and improve the hardenability of steel. High-alloy steels with a high manganese content (manganese steel) possess excellent wear resistance as well as other physical properties. (5) An increase in silicon content can increase the hardness of steel, but it reduces its plasticity and toughness. A certain amount of silicon in electrical steel can improve its soft magnetic properties. (6) Tungsten can improve the red hardness and heat strength of steel, as well as its wear resistance. (7) Chromium can improve the hardenability and wear resistance of steel, enhance its oxidation resistance, and increase its corrosion resistance. (8) Vanadium can refine the grain structure of steel, enhancing its strength, toughness, and wear resistance. When it dissolves in austenite at high temperatures, it can increase the hardenability of steel; conversely, when it exists in the form of carbides, it reduces the hardenability of steel. (9) Molybdenum can significantly improve the hardenability of steel, enhance its heat strength, prevent temper brittleness, and increase residual magnetism and coercivity. (10) Titanium can refine the grain structure of steel, thereby improving its strength and toughness. In stainless steel, titanium can eliminate or reduce intergranular corrosion in the steel. (11) Nickel can increase the strength and toughness of steel as well as its hardenability; at high levels, it can significantly alter certain physical properties of steel and alloys, thereby enhancing their corrosion resistance. (12) The role of boron is that when steel contains trace amounts of boron, in the range of 0.001–0.005%, its hardenability can be increased exponentially. (13) Aluminum can refine the grain structure of steel, inhibit the aging of low-carbon steel, and improve the toughness of steel at low temperatures. Aluminum can also improve the oxidation resistance of steel, as well as the wear resistance and fatigue strength of nitrided steel. (14) The prominent role of copper in steel is to improve the resistance of ordinary low-alloy steels to atmospheric corrosion, especially when used in combination with phosphorus.