Influence of alloy

Aluminium 1) Considerable hardening in the solid state
Al 3) Obstructs grain enlargement and this helps to prevent cracks during grinding 
  4) It is the alloy in nitriding steel. It forms extremely hard aluminium nitrides with nitrogen 
  5) Enables regulation of the depth of the nitriding layer
  6) Prevents aging of the steel
  7) Does not tend to form carbides but tends to increase the abrasive strength
  8) Harms the machinability of free cutting steels
  9) An Al / N ratio > 2 is recommended to have a good deoxidation
Arsenic 1) Has a great tendency to segregate
As 2) Worsens the tempering embrittlement
Melting point 817 °C  3) Considerably reduces the toughness
Bismuth  1) Used in an alloy with lead (~ 0.1%)  it increases the machinability of free cutting steels by 20-30% 
Bi 2) It may not be identified metallographically since it is linked with lead even if it is added separately during the production process
Melting point 270 °C 3) In hot rolling is more difficult, giving more possibility of surface defects.
Boron 1) With contents of 0,003-0,005 it considerably increases the hardening in carbon and low alloy steels. Higher contents causes brittleness when hot. If boron is allowed to combine with oxygen and nitrogen then its effect on hardenability is lost. Therefore, the steel must be deoxidised prior to the addition of boron and a strong nitride forming element such as titanium also has to be added.
B 2) Avoid temperatures of between 200 °C and 400 °C for boron steels as the material becomes fragile in this range. If tempering is to be carried out, use temperatures of 180 °C or 420 °C
Melting point 2300 °C 3) Harmful to ends of the welding, employed also like deoxidizing
  4) Increases the transition curve
Calcium 1) Even minimum quantities form non-metallic inclusions which improve machinability and resist abrasion
Ca 2) Does not worsen the mechanical characteristics and does not cause problems during heat treatment
Melting point 850 °C 3) Alkaline earth metal, which is white/silver in colour and very soft
  4) Deoxidizer for varius ferrous alloy
  5) Increase impact strength 
  6) Refines the grain and in this way holds the depht of hardening up. The quenching will be preferably made into water 
Carbon 1) It is the most important element during hardening and tempering to obtain the desired  hardness
C 2) Mild carbon steel (C < 0,15) or extra mild carbon steel (C< 0.08), without special additives, is too ductile and is  too soft during cutting which results in poor finishes 
Melting point 3499 °C 3) With a C% greater than 0,15 there is an increase in shear strength and wear of the tools due to the increased abrasiveness of the structures richer in carbons
  4) Graphite form of carbon is a black, odourless, slippery solid. Graphite sublimes at 3825 °C.  Diamond form is a clear or colored; an extremely hard solid
Chromium 1) Provides a good resistance against wear and abrasion with a high carbon content
Cr 2) Increases hardening
Melting point 1920 °C  3) Prevents corrosion, oxidisation and decarburising
  4) Helps maintain mechanical strength at high temperatures
  5) Slight tendency towards formation of carbons
  6) Increases surface hardness which can be achieved by nitruration 
Cobalt 1) Maintains hardness at high temperatures 
Co 2) Prevents overheating of machine tools
Melting point 1492 °C  
Copper 1) Increases resistance to atmospheric corrosion
Cu 2) Undesired in steel as it causes hot-shortness when hot when content exceeds 0,40% 
Melting point 1084 °C 3) Negative effects on welding
  4) Together with tungsten and molybdenum, cobalt is used to form the super high speed steels. It improves the red hardness value of the steel, that is, it enables the steel to resist softening at a high temperature or in the case of a cutting tool to hold its edge under severe conditions
Hydrogen 1) A very harmful impurity, especially if it exceeds 2 ppm
H 2) Produces micro-cracks, known as flakes, which can occur even after long periods of time or after hardening heat treatment 
Melting point -262 °C  
Lead 1) Together with sulphur, it considerably increase the machinability of steels (0,15-0,35%)
Pb 2) Slight tendency to thin the austenitic grain 
Melting point 327.4 °C 3) Negatively effects the mechanical characteristics 
  4) Harmful for welding. If welding is carried out, use UTP 63 electrodes or equivalent R 700 N/mm2 and A% 40 
  5) Tool interphase, thereby reducing friction.
Manganese 1) Helps increase hardening
Mn 2) Provides impact wear resistance
Melting point 1221 °C  3) Prevents brittleness in the presence of sulphur
  4) It is considered an alloy if it exceeds 1%
  5) Mn/C ratio must be > 3 in order to have a satisfactory toughness at low temperatures (e.g. Kv –50 °C)
Molybdenum 1) During heating it increases the temperature at which the austenitic grain starts to increase in size
Mo 2) It opposes brittleness with tempering
Melting point 2622 °C  3) Increases hot creep limit
  4) Increase depth of hardening, as it reduces the critical cooling speed
Nickel 1) Increases hardening 
Ni 2) Useful for increasing impact strength at low temperatures with a percentage of approximately 2% and excellent influence on lowering the transition curve.
Melting point 1453 °C 3) Increases strength of annealed and untreated steels
Niobium 1) Forms very hard abrasive carbons and causes an increase in the wear of machine tools. 
Nb 2) Used in self-hardening steels 
Melting point 1950 °C 3) It is also the metal used in arc welding rods for some stabilized grades of stainless steel.
  4) Used to make special steels and strong welded joints.
  5) Niobium becomes a superconductor when lowered to cryogenic temperatures
Nitrogen 1) Increases hardening, tensile strength and yield stress
2) Used in nitruration processes to obtain extremely hard surface layers 
Melting point -210 °C 3) A content of approximately  0,012% favours the cutting of the chips, thereby improving machinability
  4) Recommended max. 90 ppm 
  5) Generally considered to have negative effects on the toughness (Kv) at low temperatures
Oxygen 1) Generally considered an impurity, as it has a negative effect on the mechanical characteristics
O 2) The greater the degree of deoxidization, the higher the quality of the steel is considered to be 
Melting point -218.7 °C 3) Recommended max. 30 ppm 
  4) Oxygen is one of the chief constituents of the atmosphere of which it forms approximately one fifth. It is odourless and invisible. Although oxygen itself does not burn it is extremely efficient in supporting combustion, nearly all other chemical elements combine with it under evolution of heat. It has many uses in industry and is essential to the BOS (Basic Oxygen Steelmaking Process) 
Phosphorous 1) Reduces ductility but improves cutting in free cutting steels (0,040 – 0,11%).
2) With a content > 0.20 the impact strength is nil.
Melting point 44 °C 3) A maximum content of 0,015% is recommended for galvanising treatment, or otherwise the formula Si + 2,5P < 0,15%     
Selenium 1) 0,20% of this element is more suitable than an equal quantity of sulphur for the improvement of the cutting of carbon, low alloy and austenitic steels
Se  2) It is a better substitute for sulphur and tellurium in stainless steels
Melting point 217 °C 3) Forms manganese sulphides into globules and is used to improve the mechanical properties of resulferized steels in a transversal direction 
  4) Improves machinability in difficult deep drilling operations
Silicon 1) Used as an alloy in sheets for electromagnetic applications as it increases the electrical resistance
Si 2) Slight influence on the deoxidation
Melting point 1414 °C 3) Increase wear resistance of low alloy steels
  4) Reduces cold deformability 
  5) Seriously damages machinability of the tool
  6) A maximum content of 0,25%  is recommended for galvanising treatment
Sulphur 1) It is added to steel in various quantities depending on the classes and the technological needs to improve the machinability
2) Undesired from the point of view of the mechanical characteristics why it cause embrittlement
Melting point 118 °C 3) It is considered the simplest, most economic and effective additive to be added to steel to improve the machinability
  4) It lowers the temperature of malting point of the steel
Tellurium  1) Makes the sulphurs less plastic enabling an increased cutting speed and facilitating drilling operations
Te 2) Improves machining by up to 50% when combined with lead
Melting point 449.5 °C 3) Reduces hot deformability
  4) Reduces hot machinability like lead, when present in steel with a S% : Te%  content of ~ 10
  5) Tends to form sulphurs into globules 
Tin 1) Contents of greater than 0,05% may make the steel brittle in hot machining, just like copper
Sn 2) It is silvery-white, soft, malleable and ductile metal. Exposed surfaces form oxide film. 
Melting point 231.8 °C Resists oxygen and water
  3) When present in steel it is an undesirable impurity which gives rise to temper brittleness
Titanium 1) Prevents formation of austenite in steels with a high chromium content
Ti 2) Reduces hardness and hardening in steels with an average chromium content
Melting point 1727 °C 3) Prevents inter-granular corrosion in stainless steels  
  4) Deoxidising, denitriding and refining of austenitic grain
  5) Reduces machinability of tool as it forms abrasive carbons
Tungsten 1) Provides abrasion resistance for tool steels, reduces sensitivity to overheating
W 2) Produces mechanical strength in parts for hot-working 
Melting point 3380 °C 3) Improves toughness and prevents enlargement of grain size
  4) Used particularly in high-speed steels for cold cutting and shearing components
Vanadium 1) Produces fine grains
V 2) Increases hardening
Melting point 1726 °C 3) Increase impact strength just like nickel 
  4) Increase elastic limit
  5) Provides considerable wear resistance
Zirconium 1) Fixing nitrogen eliminates the tendency to aging
Zr 2) Tends to form oxides and nitrides which are harmful for mechanical processing
Melting point 1860 °C 3) Has the power to absorb gases and is therefore also used as a “getter” or metallic absorbent
  4) Since it cannot be altered by atmospheric agents it is used to produce corrosion resistant metal alloys
Iron This is the most common metal 90% of all the metal refined worldwide is ferrous.
Fe It is used in steels and in other alloys and the pure metal is obtained by the liquefaction of 
Melting point 1536 °C  ferrous minerals. 
  The first findings were meteorites made of iron-carbon alloy, nickel, cobalt, chromium alloys. 
  On the earth in the magnetite seams you can find hematite, limonite and siderite.
  It’s a grey and magnetic hard solid . Whether exposed to humid air, it becomes rust (iron oxide).
  Pure iron Ac3 = 911 °C