What Are The Main Elements In Steel?
What are the Main Elements in Steel?
In this article, we look at what are the main elements in steel. The different types of steel vary from how much of the different elements are included.
Carbon
Turns iron into steel and has the effect of increasing the hardness and strength by heat treatment (in steels with carbon content greater than 0.6%).
Manganese
Added to the steel alloy to increase both the yield stress (stress at which a material begins to deform) and tensile strength of low-carbon steel. The added phosphorus gives greater strength and assists the heat treatment process by reducing the temperature at which the steel naturally hardens.
Additionally, adding phosphorus to an alloy helps prevent oxidation and the rusting of metals and provides improved machinability. However, too much phosphorus can make the steel become too brittle and less ductile (harder to shape/form), so added amounts are carefully controlled.
Phosphorus
Added to improve machineability, but does decrease ductility and impact toughness so added amounts are carefully calculated.
Sulphur
Adds strength and hardness to steels (forms austenite – a very hard structure within the steel). Used in stainless steels sometimes in place of nickel.
Silicon
A main element deoxidiser in steel (used to remove oxygen from the steel to prevent gas pockets from developing/forming holes in the metal). It is used in silicon manganese, corrosion and heat resisting steels such as silver steel. Large quantities however, can make the steel form and behave more like cast iron.
Chromium
Increases corrosion and oxidation resistance. It also increases hardenability and, with the combination of high carbon levels, improves wear and abrasion resistance.
There is a much higher content of chromium in stainless steels. This enables stainless steels to be stronger and extremely resistant to corrosion/rust.
Molybdenum
Added to nickel chrome alloy steels to improve strength and hardness. It is also added to chromium nickel austenitic steels (non-magnetic stainless steels with high nickel content) as it improves corrosion resistance. Some high speed quality steel grades contain molybdenum.
Nickel
This is an important element. Nickel increases hardenability, tensile and impact values of steels. Nickel produces austenitic (very hard) structures which gives high temperature strengths to steels and impressive resistance to oxidation and corrosion. It is added to high chromium stainless steels in amounts of over 6%.
Copper
Sometimes present in stainless steels. It aids precipitation hardening (heat treatment) properties. Used in steels known as “weathering” steels (these eliminate the need for painting, and form a stable rust-like appearance if exposed to the weather for several years).
Titanium
Titanium – The main use of titanium as an alloying element in steel is for carbide stabilisation. It combines with carbon to form titanium carbides, which are quite stable and hard to dissolve in steel. When adding approximately 0.25%/0.60% titanium, the carbon combines with the titanium instead of the chromium content.
If the carbon combines with the chromium too much, it forms large crystals which cause pockets within the steel allowing rust/corrosion penetration. The titanium content prevents this and gives added strength and corrosion resistant properties to the steel.
Selenium
Added to improve machinability.
Boron
Added to steel to aid heat treatment (enhances hardenability). Due to its ability to aid in high temperature strength properties, boron is sometimes added to austenitic stainless steel grades.
Vanadium
Improves wear resistance and fatigue stress when added to alloy steels. Added to quality tool steels for this reason.
What element amounts are added to the steel?
How much (weight quantity) of each element added depends on the type of steel alloy required. The overall quantity of each element within the alloy is shown in percentages (%’s).
