List of alloying elements

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This is an incomplete, alphabetically ordered list of alloying elements and their desired (positive) and undesirable (negative) effects on the respective base metal:

Aluminum (Al)

In the iron

positive
Aluminum is a powerful deoxidizer used to calm steel . It forms nitrides ( nitriding steel ) with nitrogen and increases the scaling resistance in heat-resistant steels. It is used in permanent magnet alloys by increasing the coercive force .

In magnesium

To increase strength. Of the magnesium alloys , MgAl is the most important group.

Arsenic (as)

In the copper

positive
As white copper, arsenic is a substitute for silver .
negative
Arsenic is toxic.

Beryllium (Be)

In the iron

positive
Beryllium cuts off the γ region ( austenite ); acts as a powerful deoxidizer ; increases precipitation hardening .
negative
Beryllium lowers the toughness .

In the copper

positive
Beryllium increases elasticity and fatigue resistance . Watch springs made from this alloy can withstand a much greater number of load changes than steel springs. In addition, this alloy is hardly magnetizable
As an alloy additive, it enables the production of non-sparking tools in coal mining.

In the nickel

positive
Beryllium greatly increases hardness and corrosion resistance .

In magnesium

positive
Beryllium reduces the tendency to burn (oxidation) of magnesium melts.

Lead (Pb)

General

positive

Small amounts of lead (up to 2%) increase the machinability . It is added in various alloys for this purpose. These are commonly referred to as free-cutting alloys, such as free-cutting steel .

negative

Health problems and legal restrictions.

In the copper

Lead bronzes are used as a bearing metal for internal combustion engines.

Boron (B)

In the iron

positive
Boron is a strong neutron absorber and is used in the manufacture of steels for nuclear power plant construction . It increases the yield point and strength .
negative
Boron lowers the corrosion resistance. In cast iron with spheroidal graphite, it reduces pearlitization, forms carbides if the content is above 0.001% and thus leads to embrittlement.

In aluminum

positive
Increases the electrical conductivity in aluminum alloys . In conjunction with titanium, it refines the grain structure.

Cerium (Ce)

In the iron

positive
Cerium is a strong deoxidizer and increases the scale resistance. In cast iron with spheroidal graphite, it promotes the formation of spheroidal graphite. Cerium-iron alloys (up to 30% iron ) are pyrophoric .

Chromium (Cr)

In the iron

positive
Chromium greatly reduces the critical cooling rate , increases wear resistance , heat resistance and resistance to scaling . As a carbide former ( chromium carbide ) it greatly increases the tensile strength . From a mass content of 12.2%, it increases the corrosion resistance ( stainless steel ). It has a ferrite- stabilizing effect , but with small additions it also expands the austenite area to lower temperatures.
negative
Chromium reduces the impact work and weldability , lowers thermal and electrical conductivity , stop point A 1 is shifted significantly upwards (by 20 to 30 K per 1% Cr, but only up to 3%).

Carbon (C)

In the iron

positive
Carbon lowers the melting point, while cementite (Fe 3 C) formation increases hardness and tensile strength. Steel can only be hardened from a content of 0.2% .
negative
At higher contents, carbon increases the brittleness and therefore lowers forgeability , weldability, elongation at break and impact energy.

See also: carbon steel

Copper (Cu)

In aluminum

positive
Copper increases the hardness and strength significantly, the alloy duralumin is created through precipitation hardening . Main alloy element in aluminum-copper alloys , and as an additive in many others.
negative

Increases corrosion

In steels

positive
Copper increases weather resistance. In construction and quality steels, 0.2 - 0.35% copper is added to increase the rust resistance. In addition, in chromium-nickel steels, the resistance to hydrochloric and sulfuric acid can be increased by using Cu concentrations of 1–2% .
negative
During the hot processing of steels containing copper, copper enriched on the surface can penetrate the grain boundaries under the effect of tensile stress and lead to surface cracks

In gold

positive
Copper increases the hardness and electrical conductivity, changes the color (darker, reddish), and the alloy is cheaper than pure gold.
negative
Copper lowers the resistance to corrosion.

In zinc

positive
Copper improves creep behavior , increases fatigue strength and, together with lead , increases the machinability.

magnesium

In the iron

positive
Deoxidizing and desulfurizing agents . Magnesium produces spheroidal graphite in cast iron

In aluminum

positive
Together with manganese, it increases strength and corrosion resistance

Manganese (Mn)

In the iron

positive
Manganese forms drop-shaped, higher melting MnS - FeS mixed sulphides, which reduce the tendency to red fracture.
negative
The stopping point A 1 is shifted downwards by 10 K per 1% Mn.

In magnesium

positive
Manganese increases the corrosion resistance.

In aluminum

positive
Increases strength. See aluminum-manganese alloy .

Molybdenum (Mo)

In the iron

positive
Molybdenum improves hardenability and tensile strength. Important alloying element in many high-speed steels .
negative
Molybdenum slightly shifts the stop point A 1 upwards, lowers forgeability and elongation .

Nickel (Ni)

In the iron

positive
Nickel increases in structural steels the yield strength and impact strength , and in case-hardening steels , as well as treated steels , the toughness, the γ-region and causes extended characterized in corrosion and scaling-resistant chromium-nickel steels , the austenitic structure. High nickel contents in the Invar cause small or sometimes negative coefficients of thermal expansion .
negative
Nickel lowers the stop point A 1 by 10 K per 1% Ni.

Phosphorus (P)

In the iron

positive
Phosphorus increases tensile strength, hardness, corrosion resistance, machinability and castability . Is deliberately added to some types of cast steel and free- cutting steel .
negative
Phosphorus shifts the stop point A 1 slightly upwards and causes a strong constriction of the gamma area, which leads to an increase in segregation . Even the smallest amounts increase the sensitivity to temper embrittlement .

Sulfur (S)

In the iron

positive
Sulfur increases the machinability, especially together with manganese , with which it forms manganese sulfide . Used in free cutting steel .
negative
Sulfur reduces ductility and strength by forming iron sulfide .

Silicon (Si)

In the iron

positive
Silicon is a deoxidizer for calming steel, increases the scale resistance, makes the melt more fluid , is a solid solution hardener and prevents the formation of carbides. Many cast steel - and all types of cast iron contain 1 to 2% silicon.
negative
Silicon reduces the toughness, the stopping point A 1 is strongly shifted upwards (by 20-30 K per 1% Si, but only up to 3%).

In aluminum

Used as the main alloy element in aluminum-silicon alloys , which are mainly used as cast alloys . Lowers the melting point and the volume difference during solidification. Together with magnesium, forms intermetallic phases that are used for hardening aluminum-magnesium-silicon alloys .

Nitrogen (N)

In the iron

positive
Nitrogen expands the γ area in the iron-carbon diagram , stabilizes the austenitic structure, and increases the yield point, strength and corrosion resistance ( PREN ) in austenitic steels .
negative
Reduction of toughness, favors intergranular stress corrosion cracking in unalloyed and low-alloy steels.

Titanium (Ti)

In the iron

positive
Titanium prevents intergranular corrosion through the formation of titanium carbide (TiC).

Vanadium (V)

In the iron

positive
As a carbide former, vanadium greatly increases the tensile strength.
negative
Vanadium slightly shifts the stopping point A 1 upwards.

Tungsten (W)

In the iron

positive
As a carbide former ( tungsten carbide ), tungsten greatly increases tensile strength and hardness, as it 'transfers' many of its properties more or less well to its alloys. The heat resistance and wear resistance also increase. Main alloy element in some high-speed steels .
negative
The stop point A 1 is slightly shifted upwards by tungsten.

In hard metals

Through the formation of tungsten carbide as a hardening agent and main component in many types of hard metal.

Zinc (Zn)

In the copper

positive
As an alloy component in brass , approx. 30 + 40%, it increases its strength, improves deformability, work hardening, corrosion resistance and sliding properties.
Together with nickel it forms German silver .

Tin (Sn)

In the copper

positive
As an alloy component of up to 22% in bronze , it increases elasticity, toughness, corrosion resistance and castability .

Web links

Individual evidence

  1. ↑ Prof. Dr. Ing Uwe Reinert: Influence of alloying elements on ferrous materials. In: University of Bremen. Retrieved on August 23, 2019 (German).