The effect of alloying elements
To improve the corrosion resistance, strength and technological properties of the composition of metals introduce various alloying elements. For alloying steels use vanadium, tungsten, manganese, Nickel, niobium, titanium, chromium and others zinc Supplements on copper and bronze enhance the strength, ductility, corrosion resistance Small additives of cadmium to copper increases the wear resistance of wires. When alloying titanium with molybdenum will double the temperature limit of operation of the alloy due to the change in its crystalline structure. Doping involves the introduction of one or more elements, which give the alloy special properties.
Alloying structural steel considerably increases its durability. Major component in structural steel is ferrite. It in the structure of the alloy is 90%. The alloying elements dissolved in the ferrite, strengthen the structure. The hardness of the alloy stronger than others increase the silicon, manganese and Nickel. Molybdenum, tungsten and chromium effect is weaker. Most alloying elements, the hardening structure and little effect on ductility, lower notch toughness (with the exception of Nickel).
How is hardening
Alloying strengthens the ferrite. The alloying elements increase the hardness, strength and toughness, increase the stability of austenite, hardenability, etc. So for steels that are used for the manufacture of turbines, boilers, etc. equipment, of particular importance is the corrosion resistance and heat resistance. Alloying elements can be dissolved in ferrite or austenite, to form carbides, to give intermetallic compounds, arranged in the form of inclusions, not interacting with the ferrite and austenite or carbon.
Depending on the nature of the interaction of alloying additives with iron or carbon, are determined by the properties of the steel. The ferrite may, in varying degrees, to dissolve all the elements. The dissolution of the alloying additives in the ferrite allows to uprajnenii steel without heat treatment. The tensile strength and hardness increase and toughness is usually reduced. All of the elements soluble in iron, influence on the stability of austenite and ferrite. Critical points of alloy steels are shifted under the influence of the quantity and quality of the alloying additives. Therefore, when choosing a mode of hardening, normalizing, annealing and tempering should take into account the shift of critical points.
Mn and Si
They are technological and impurities are introduced into the steelmaking process to deoxidize. The proportion of Mn in steel — up to 2%. It is distributed between cementite and ferrite and significantly raises the threshold of cold brittleness, hardenability and yield strength, but makes the steel susceptible to overheating. Therefore, the grain refinement in the alloy with manganese is administered carbidopa elements. Since all steels the manganese content is approximately the same, its impact on the change of properties of steel of different composition slightly. It increases the strength of steel without changing the plasticity.
The deoxidation of steel
Mn and Si occur in almost any steel. Silicon along with manganese and aluminium is the main deoxidizer. Mn is also necessary for «binding» in steel sulfur and the elimination of brittleness. Additives these elements usually do not exceed 0,17 — 0,37% Si, 0,3 — 0,7% Mn and about 0,03% Al. Within these limits they are considered technological additives and are not alloying elements. Special introduction of these additives is above the specified level to give steel certain properties will have to be doping.
It is not carbidopa element, and its share in the steel are usually less than 2%. It significantly increases the yield strength and the strength of steel and at a content above 1% reduces the viscosity, plasticity and raises the threshold of cold brittleness. Silicon is structurally not detected, as is normally soluble in ferrite, except for the part of silicon, which is in the form of oxide do not have time to float in the slag and left in the metal in the form of inclusions.
To buy, price
In stock, LLC «Electrocentury-steel» a wide range of high-quality metal standard and custom sizes. Supply products made of alloys in retail and wholesale. All production is certificated on conformity to requirements of standards and technical conditions. In the certificate marked by the manufacturer, drawing number and name of the product alloy grade, number of melt, parts, chemical composition, mechanical properties, and results of additional tests. Implementation of orders in the shortest possible time. Wholesale buyers are offered preferential discounts.
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