INFLUENCE OF ALLOYING IN STEEL

   

BILBAINA DE TRATAMIENTOS

Travesia Mercadillo,36, 48960 Galdakao (Vizcaya)
Tel: 944562512    Fax: 944562554
E-mail: biltra@biltra.com
Contacto: comercial@biltra.com


The steels contain alloying elements that improve some features fundamentales.Los carbon steels, as a rule, contain:. carbon, silicon, manganese, phosphorus and sulfur, therefore, call alloy steel, to Steels addition to the above five elements, containing alloying as nickel, manganese, chromium, vanadium, tungsten, molybdenum, cobalt, silicon, copper, titanium, zirconium, lead, selenium, niobium, aluminum and boron .
The influence of these elements is very different, and, using the convenient percentage obtenemosaceros diferentes.Podemos features make parts very thick, very high strengths within the same tools that perfectly resist the action of agents corrosive, mechanical components which reach high hardness with high toughness, resistance mechanisms remain high, even at high temperatures, molds very complicated shapes that do not deform or crack in the temple, etc.These alloying can be dissolved in the ferrite or form solutions solid with alpha or iron, may have a tendency to form carburos.Algunos alloying raise or decrease the critical temperatures of equilibrium diagrams, Ac and Ar, iron-carbon diagram.

Widen or reduce the austenitic or ferritic field equilibrium diagram, and other influences, also related to the iron-carbon diagram and tendency to graphitize the carbon, to modify the grain size, etc.

NICKEL-Ni

The nickel prevents grain growth in the heat treatments, which serves to produce them great tenacity. Nickel also lowers the critical point Ac and therefore treatments can be slightly lower than that corresponding to ordinary steels temperatures.

In steels alloyed with nickel is obtained for the same hardness, a limit of elasticity and slightly higher elongation and higher resistance than carbon steel or low alloy steel.

Nickel is essential in the manufacture of stainless steel and / or high temperature resistant steel, in which chromium plus nickel percentages of from 8% to 20% are used.

Nickel dissolves in the ferrite is not a big carbides forming

Increases toughness and the resistance of the annealed steels, tending to retain austenite steels in high Chrome

CORMO-Cr

It is the most widely used alloying special alloy steel, it being used interchangeably in steel construction in tools in stainless and heat resistance.

Use:

– Increases the hardness and tensile strength of steels

– Improves hardenability,

– Prevents deformation hardening

– Increases resistance to wear and abrasion

– Increases resistance to high temperatures

– Provides stainlessness, etc..

Chromium is dissolved in the ferrite and shows a strong tendency to form chromium carbides and complex carbides.

MOLYBDENUM-Mo

This alloying provides a high tensile strength, by increasing the hardenability and the resistance to mechanical creep or deformation displacement grain steel work due to prolonged high temperature creep of steel.

Molybdenum in chrome-nickel steels eliminates temper brittleness or fragility

Krupp, which occurs when these steels are tempered in the area of ​​450 ° to 550 °.

Molybdenum also increases the resistance to the hot steel and tungsten replaces manufacture high speed steels, and can be used for the same applications molybdenum approximately one part per two tungsten.

Molybdenum dissolves in ferrite, it is a big forming carbides, but also is high stabilizing these.

Retards the softening of steels during tempering, appearing high hardness.

wolfram (tungsten)-W

With this alloying is present in the manufacture of most of the tools,

Its use is widespread in high speed steels, tool steels and steels for cutting hot work.

It allows us to maintain the hardness at high temperature steels and preventing it blunt and softening in the tools, but reach temperatures above 500 ° C or 600 ° C.

Tungsten dissolves slightly in the ferrite and has a great tendency to form carbides.

The tungsten carbides have high stability.

The tungsten forms very hard and wear resistant carbides at high temperatures, and improves the hardness of the steels at elevated temperatures.

Retards the softening of steels during tempering, appearing high hardness.

VANADIUM-V

This alloying, also present in the manufacture of most of the tools, tends to refine the grain and reduce the hardenability. It is a strong deoxidizing element.

Vanadium is a great trainer carbide, so their percentage is very small, 0.02% / 0.03%, except tool steels,.

Severely hampers the softening temper, and gives rise to the phenomenon of high hardness.

You can not influence the hardenability if it is dissolved.

Manganese-Mn

This alloying provides the necessary balance to the disadvantages of sulfur and oxygen present in the manufacturing process.

With oxygen

Manganese is a deoxidizing preventing gases arising in the solidification of steel and pores and voids originating in steelmaking.

With sulfur

The manganese steels allows us laminar and forge, because sulfur commonly found in steels, form iron sulfides, which has very low melting point (981 ° approx.) And that working temperature hot melts and weaken.

Manganese in steel, increases strength, hardenability, still interesting to note that it is a relatively inexpensive alloy element. Form carbides.

SILICON-Si

This gives us great deoxidizer alloying, manganese supplementary power to avoid the appearance of pores and voids.

Improved steels hardenability graficitantes no elements and increases the resistance of low carbon steels, the yield strength significantly increases and the fatigue resistance of the steel without reducing toughness.

COBALT-Co

usoen limits its upper grades of high speed steels. This alloying, combined with the ferrite core, increasing its hardness and strength. Decreases hardenability. steels in high carbon

For those based tungsten steels, hardened ferrite thereby facilitating the maintenance of strength and fitness cutting tools at high temperature.

It is one of the few alloying elements that move the eutectoid point to the right and reduces the hardenability of steels.

ALUMINUM-Al

This alloying steels used in the nitriding, which tends

have approximately 1% aluminum.

As deoxidizer is commonly used for large number of steels. All high quality alloy steel containing aluminum but in low percentage.

TITANIUM-ti

Its use as an alloying steels only applies to high end and low amounts, deoxidizer for his great power and his great ability to tune the deoxidiser and refine the grain. Forming a large carbides and combines rapidly with nitrogen.

It is also used in chrome-nickel stainless steels.

BORO-Bo

This is newly minted alloying in the steel market. Recent research studies make clear that trace amounts of boron in the range 0.001 to 0.006%, greatly improving the hardenability, being the most effective alloying and hardening of greater capacity.

The hardenability is so great, that for the same steels 0.40% carbon, the alloy is:

– 50 times the molybdenum

– 75 times the chromium

– 150 times that of manganese

– 400 times higher than nickel

The use of this element is quite challenging, as it is a very strong oxidizing.

Steels used in 0.30 to 0.50% carbon.