Alloying elements used in steel nickel, chromium, molybdenum, cobalt, vanadium, manganese, silicon and tungsten. Each element has a certain quality steels are added. These elements can be used separately or in combination to produce the desired characteristics in steel.
Here is the effect of alloying elements in steel.
A. Nickel. Steel containing 2 to 5% nickel and 0.1-0.5% carbon increases the strength and toughness. In this range, nickel major contribution tensile strength, yield strength, toughness and shape and hardness properties with high elastic limit, good ductility and resistance to corrosion. An alloy containing 25% nickel has a maximum toughness and offer the greatest resistance to rust, corrosion and burn at high temperatures.
B. Chromium, improve corrosion resistance, increase the tensile strength, hardness, wear resistance and heat resistance. It provides property stainless steel. Reduce spasticity steel. Is used as an alloying element in steel to combine hardness with high strength and high elastic limit. Adding corrosion resistant properties to steel. The most common chrome steel containing 0.5-2% chromium and 0.1 to 1.5% carbon. Chrome steel is used for ball, roller bearings and races for. A Nickel-Chrome steel containing 3.25% nickel, 1.5% chromium and 0.25% carbon is widely used for steel plate. Chrome nickel steel is widely used for automobile crankshafts, axles and gears that require great strength and hardness.
C. Tungsten, increase hardness, wear resistance, shock resistance and magnetic reluctance. This improves the ability to maintain the hardness and toughness at high temperatures. Increase wear resistance, shock resistance, toughness, and depth of hardening steel quenched.
D. Vanadium. Increasing tensile strength, elastic limit, ductility, fatigue resistance, shock resistance and response to heat treatment. It also acts as a degasser when added to molten metal. The addition of a very small amount of vanadium (less than 0.2%) resulted in a marked increase in tensile strength and elastic limit at low and medium carbon steels without loss of ductility. Chrome vanadium steel contains about 0.5 to 1.5% chromium, 0.15 to 0.3% vanadium and 0.13 to 1.1% carbon has excellent tensile strength, elastic limit, limit of endurance and tenacity.
E. Molybdenum. In a very small amount (from 0.15 to 0.30%) of molybdenum is commonly used with chromium and manganese (0.5 to 0.8%) to make a molybdenum steel. This increases the hardness, wear resistance, heat resistance. When added with nickel, improves corrosion resistance. Case against the tendency of angry fragility. It makes tough steel at various levels of violence. It acts as an inhibitor of grain growth when the steel is heated to a high temperature. Molybdenum steel has a hardness, wear resistance, heat resistance and tensile strength extras. It is used for air-plane and automobile parts. It can replace tungsten in high speed steel.
F. Cobalt. When added to steel, it purifies graphite and perlite and acts as a grain refiner. Improved hardness, toughness, tensile strength and heat resistance.
G. Titanium. Serves as a good deoxidizer and promote grain growth. It prevents the formation of austenite at high chromium steel. It is a strong carbide former. It is used to fix carbon in stainless steel and thus prevent the precipitation of chromium carbides.
H. Aluminum. Used as a deoxidizer. If present in an amount of about 1%, it helps promote nitriding.
I. Copper. Increasing resistance to corrosion. This increases the strength. More than 0.6 percent copper for precipitation.
J. Silicon. Increasing the magnetic permeability and reduce hysteresis losses. It reduces the weldability and forgeability. It is also added as a deoxidizer during ingot casting. It takes care of the oxygen present in the steel by forming SiO2. Silicon steel behaves like nickel steel. This steel has a high elastic limit compared with ordinary carbon steel. Silicon steel containing 1 to 2% silicon and 0.1-0.4% carbon and other alloying elements are used to power machinery, valves in IC engines, springs and corrosion resistant materials.
K. Mangan. Increasing the strength of steel in both conditions of hot rolled and heat treated. Manganese alloy steel containing more than 1.5% manganese with various carbon from 0.40 to 0.55% is used extensively in gear, axles, shafts and other parts where high strength combined with a fair ductility required. The main use of manganese steel on the engine suffered severe wear.
L. Carbon. Increasing tensile strength and hardness. It reduces the ductility and weldability. It affects the melting point.
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