Silicon (Si)

Silicon (Si)
Silicon is soluble in ferrite and austenitic steel of improving the strength and rigidity, its role after phosphorus, a manganese, nickel, chromium, tungsten, molybdenum and vanadium elements such as strong. But more than 3% containing silicon, will significantly reduce steel plasticity and toughness. Silicon can improve steel the elastic limit, yield strength and yield ratio (σ s/σ b), and fatigue strength and fatigue than (the same 1 / σ b) and so on, this is silicon or silicon manganese steel can be used as spring steel kind of reason.
Silicon can reduce the density of steel, thermal conductivity and conductivity. Can cause ferrite grain coarsening. Reduce the coercive force. Have reduced crystal anisotropic tendency, make magnetized easy, magnetic resistance decreases, and can be used to produce electrical steel, so the manufacturing of hysteresis losses is low, silicon can improve the ferrite magnetic conductivity, make steel is weak magnetic field in a higher sense of magnetic strength. But in a strong magnetic field, silicon steel magnetotactic strength of the lower. Because of having a strong 'silicon force, thus reduce iron magnetic aging role.
Containing silicon steel in the oxidation atmosphere heating, surface will form a layer of SiO2 thin film, so as to improve the steel in high temperature of oxidation resistance.
Silicon can cause in cast steel columnar crystal growth, lower the plastic. If silicon steel heating and cooling fast, due to the low thermal conductivity, steel internal and external temperature difference is bigger, so easy to crack.
Silicon steel welding properties can reduce. Because the affinity with oxygen silicon better than iron, in welding was easy to generate silicate with low melting point, increase the slag and melting metal liquidity, cause spitting phenomenon, affect welding quality. Silicon is good deoxidizer. Al killed with a certain amount of silicon ZhuoJia when, can significantly improve the ability of deoxidizing aluminum. Silicon in steel had a certain residual, this is because the ironmaking as raw materials into steel. In the country, silicon limit in < 0.07%, to want to join, then add in steelmaking silicon alloy.
(1) for the organization and show do steel heat treatment effect
A, as steel of the alloying elements, its content generally not be less than 0.4%. To form the crystallology exists in ferritic or austenitic, narrow austenitic phase area
B, improve annealing, is fire and quenching temperature, in YaGongXiGang improve its quench-hardening ability
C, silicon not form carbide, strong promote carbon graphite when the role in the high silicon content of carbon and high carbon steel, such as not contain strong carbide form elements, easy in a certain temperature conditions occur graphitization
D, in carburizing steels, silicon reduce carburizing layer thickness and the concentration of carbon
E, silicon steel to have good role deoxidization
(2) for the role of the mechanical properties of the steel
A, improve the ferrite and austenitic hardness and strength, and its function is Mn, Ni, Cr w., Mo, V, stronger; Improve steel the elastic limit, yield strength and ultimate than (σ s/σ b.) and improve labor strength and fatigue should be than (the same 1 / σ b)
B, silicon content in significantly more than 3% lower steel plasticity and toughness; Silicon improve plastic/brittle transition temperature
C, silicon make easily in steel form bands organizations, horizontal performance below the longitudinal performance
D, improve steel abrasion resistance
(3) of steel of physical, chemical and process performance role
A, reduce the density of steel, thermal conductivity, conductivity and temperature resistance coefficient
B, the manufacturing of the loss of the eddy is significantly lower than the pure iron, coercive force, magnetic resistance and low hysteresis losses. Magnetic conductance and magnetic feeling high strength. But in a strong magnetic field, silicon reduce magnetotactic strength
C, improve the high temperature ShiGang antioxidant properties, but high silicon content, surface decarburization intensified
D, silicon content more than 2.5% of the steel, its deformation processing more difficult
E, silicon reduce steel solderability
(4) in the application of steel
A, in the ordinary low steel/" target="_blank" class="keylink">alloy steel of improving the strength, improve local corrosion resistance, in conditioning improve its quench-hardening ability and resisting steel watery back, is the main multivariate steel/" target="_blank" class="keylink">alloy steel and alloy group one of the yuan
B, silicon content is 0.5%-2.8% of the SiMn or SiMnB steel (carbon content 0.5%-0.7%) is widely used in high load the yellow material, at the same time with W, V, Mo, Nb, Cr, strong carbide form elements
C, silicon steel for containing silicon 1. O %-4.5% of the low carbon and ultra-low carbon steel, used in motor and transformer
D, in stainless steel and corrosion resistant steel, and Mo, W, Cr, Al, Ti, N, cooperate, improve corrosion resistance and high temperature oxidation ability
E, high silicon content of steel used in cold mould graphite materials