TECHNICAL INFORMATION

DESCRIPTION AND PARTICULARITIES OF STEEL
EFFECT OF ALLOY ELEMENTS ON STEEL
UNIT WEIGHTS OF STEEL RODS
HEAT TREATMENTS APPLIED TO STEELS
HARDNESS TRANSFORMATION TABLE
NONDESTRUCTIVE TEST METHODS
EFFECT OF ALLOY ELEMENTS ON STEEL

Carbon (C ):
It is one of the fundamental elements that form steel. The resistance and hardness of unalloyed steels increases substantially as the amount of carbon increases. Since the pearlite rate in the steel will increase as the carbon amount increases, steel resistance and yielding point increase yet the ductility, malleability, deep drawability and weldability of steel diminish and crack-deformation tendency increases.

Manganese (Mn):
It increases the resistance of steel but somewhat decreases its ductility. It improves its malleability and hardenability. It doesn't adversely affect welding capacity so up to 1.6% Mn is added in weldable steels with low carbon but high resistance. High manganese and carbon steels have austenitic structure and highly resistant to wear. It improves surface quality.

Silium (Si):
It is the element used as oxygen compensator in steel production. Corrosion resistance is good in steels with 14-15% Si, but they are not malleable and they are fragile. The grain size of steel increases as silisium amount increases. Silisium increases the hardness of steel, but its effect is much less than manganese. Steel hardenability, wear resistance and elasticity increases, with an adverse effect on surface quality.

Sulfur (S):
It is an undesired element except for automate steels, and tried to be reduced at all times. As sulfur amount increases, ductility and impact resistance decreases as perpendicular to the formation, and effect is low in longitudinal direction. If not balanced with manganese, it causes fragility in hot temperatures, and its weldability and hardenability deteriorates.

Phosphorus (P):
Ferritin is the element which increases its resistance most. Therefore, it increases the resistance and hardness of steel even in small quantities, in contrast to reducing the ductility and impact resistance in terms of formation. Although it improves the corrosion resistance of steel, it is tried to have only a little amount in steel along with sulfur and it plays the most significant role in setting quality.

Chromium (Cr):
It increases resistance to oxidation and corrosion, wear resistance and hardenability of steel.Since it is a carbide making element, it increases the tensile strength and heat resistance, and reduces ductility.

Nickel (Ni):
It increases the resistance of steel, and although the increase is less compared to silicon and manganese there is no substantial decrease in ductility. It increases hardenability. It shows high ductility, high hardenability and high fatigue resistance particularly when used with chromium. It improves resistance to heat and oxide layer formation.

Molybdenum (Mo):
It is a strong carbide and nitride forming element. It increases the hardenability, tensile strength and heat resistance because it is generally with chromium in low alloy steels however, it reduces temper fragility.

Vanadium (V):
It increases hardenability, forms nitride by combining with nitrogen causing grain downsizing in ferritic structure. Therefore, it raises notch strength. Since it is a strong carbide former, it is used with wolfram in tool steels to increase wear and heat resistance, and with chromium in heat-resistant steels.

Wolfram (W):
It increases the strength of steel. It causes secondary hardening particularly in speed steels and increases temper resistance. The effect is due to carbide formation, and the carbides increase wear resistance.

Niobium (Nb):
It is used particularly in high resistance low alloy steels to improve features by rolling and cooling and in heat-resistant steels. It is a strong carbide and nitride former. It increases hardness, thins grains and reduces deformability.

Titanium (Ti):
It is a strong carbide and nitride former. It generally thins the grain structure in steels.

Zirconium (Zr):
It is mostly used as purifier of non-purifiable elements in very high strength low alloy steels. It particularly changes the form of sulfurs and increases ductility.

Cobalt (Co):
It doesn't form carbide, however increases heat resistance. It decreases hardening, and is used mostly in speed steels and heat-resistance steels because it slows down grain growth at high temperatures. If affects magnetic particularities of the steel positively.

Aluminum (Al):
It is the strongest deoxidizer element. It forms nitride along with nitrogen, and heating reduces grain coarsening and age-hardening inclination of the steel. It is the grain thinner element in steel production.

Boron (B):
It is an element increasing hardenability and forming nitride in low and medium carbon steels .

Copper (Cu):
It increases resistance and hardness, and highly decreases ductility of steel. It improves corrosion resistance. An increase of 0,5% buildup is not desired in steel production because it causes fragility in hot working.

Lead (Pb):
It is added to make shavings in automate steels fragile only because it does not dissolve in steel, but homogenous and thin distribution is required in structure.

Nitrogen (N):
It is a nitride forming element. It causes aging in steel. Where age-hardening is not a problem, it increases hardening, mechanical strength and resistance to atmosphere corrosion.

Effect of Alloy Elements on Steel
  Si Mn* Mn** Cr Ni* Ni** Al W V Co Mo S P
Hardness increases increases decreases increases increases decreases - increases increases increases increases - increases
Endurance increases increases increases increases increases increases - increases increases increases increases - increases
Yield Point increases increases decreases increases increases decreases - increases increases increases increases - increases
Elongation No change No change decreases decreases No change increases - decreases No change decreases decreases decreases decreases
Reduction in cross-sectional area decreases No change No change decreases No change increases - decreases No change decreases decreases decreases decreases
Impact Resistance increases No change - decreases No change increases decreases - increases decreases increases decreases decreases
Elasticity increases increases - increases - - decreases - increases - - - -
Resistance to Heat decreases No change - increases increases increases - increases increases increases increases - -
Cooling Speed decreases decreases decreases decreases decreases decreases - decreases decreases decreases decreases - -
Carbide Formation decreases No change - increases - - - increases increases - increases - -
Wear Resistance decreases decreases - increases decreases - - increases increases increases increases - -
Malleability decreases increases decreases decreases decreases decreases decreases decreases increases decreases decreases decreases decreases
Processability decreases decreases decreases - decreases decreases - decreases - No change decreases increases decreases
Oxidation Tendency decreases No change decreases decreases decreases decreases decreases decreases decreases decreases increases - decreases
Corrosion Resistance - - - decreases - increases - - increases - - decreases increases


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