Influence of alloy

Aluminium
1) Considerable hardening in its solid state
Al 2) It deoxidises effectively; casting percentage 0,020 – 0,040% or > 0,015 for soluble Al
Melting point 3) It obstructs grain enlargement; that helps to prevent cracks during grinding
658 °C 4) It is an alloy in nitriding steel; it forms extremely hard aluminium nitrides with nitrogen
5) It enables regulation of the nitriding layer depth
6) It prevents the ageing of steel
7) It does not tend to form carbides but it tends to increase the abrasive strength
8) It damages the machinability of free cutting steels
9) Al / N ratio > 2 is recommended to have good deoxidation
Arsenic | As
1) Great tendency to segregate
Melting point 2) It worsens the tempering embrittlement
817 °C 3) It reduces considerably the toughness
Bismuth | Bi
1) If used in an alloy with lead (~ 0.1%), it increases the machinability of free cutting steels by 20-30%
Melting point 2) It may not be identified metallographically since it is linked with lead even if it is added separately during the production process
270 °C 3) In hot rolling is more difficult, giving more possibility of surface defects
Boron | B
1) With 0,003-0,005 content, it considerably increases 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. 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
Melting point 2) Avoid temperatures between 200 °C and 400 °C for boron steels since the material becomes fragile in this range. If tempering is to be carried out, use temperatures of 180 °C or 420 °C
2300 °C 3) Harmful for welding purposes; it is also employed as deoxidizing
4) It increases the transition curve
Calcium | Ca
1) Even in minimum quantities, it forms non-metallic inclusions which improve machinability and obstruct abrasion
Melting point 2) It does not worsen the mechanical characteristics and does not cause problems during heat treatment
850 °C 3) Alkaline earth metal, colour white/silver and very soft
4) Deoxidizer for varius ferrous alloy
5) It increases the impact strength
6) It refines the grain, thus holding the depht of hardening up; quenching may be preferably carried out in water
Carbon | C
1) It is the most relevant element to obtain the desired hardness during hardening and tempering
Melting point 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
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 3) Prevents corrosion, oxidisation and decarburising
1920 °C 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 | Co
1) Maintains hardness at high temperatures
Melting point 2) Prevents overheating of machine tools
1492 °C
Copper | Cu
1) Increases resistance to atmospheric corrosion
Melting point 2) Undesired in steel as it causes hot-shortness when hot when content exceeds 0,40%
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 | H
1) A very harmful impurity, especially if it exceeds 2 ppm
Melting point 2) Produces micro-cracks, known as flakes, which can occur even after long periods of time or after hardening heat treatment
-262 °C
Iron | Fe
1) This is the most common metal 90% of all the metal refined worldwide is ferrous.
Melting point 2) It is used in steels and in other alloys and the pure metal is obtained by the liquefaction of ferrous minerals. The first findings were meteorites made of iron-carbon alloy, nickel, cobalt, chromium alloys.
1536 °C 3) On the earth in the magnetite seams you can find hematite, limonite and siderite.
4) It’s a grey and magnetic hard solid . Whether exposed to humid air, it becomes rust (iron oxide).
5) Pure iron Ac3 = 911 °C
Lead | Pb
1) Together with sulphur, it considerably increase the machinability of steels (0,15-0,35%)
Melting point 2) Slight tendency to thin the austenitic grain
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 3) Prevents brittleness in the presence of sulphur
1221 °C 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 3) Increases hot creep limit
2622 °C 4) Increase depth of hardening, as it reduces the critical cooling speed
Nickel | Ni
1) Increases hardening
Melting point 2) Useful for increasing impact strength at low temperatures with a percentage of approximately 2% and excellent influence on lowering the transition curve.
1453 °C 3) Increases strength of annealed and untreated steels
Niobium | Nb
1) Forms very hard abrasive carbons and causes an increase in the wear of machine tools.
Melting point 2) Used in self-hardening steels
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 | N
1) Increases hardening, tensile strength and yield stress
Melting point 2) Used in nitruration processes to obtain extremely hard surface layers
-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 | O
1) Generally considered an impurity, as it has a negative effect on the mechanical characteristics
Melting point 2) The greater the degree of deoxidization, the higher the quality of the steel is considered to be
-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%).
P 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 3) Forms manganese sulphides into globules and is used to improve the mechanical properties of resulferized steels in a transversal direction
217 °C 4) Improves machinability in difficult deep drilling operations
Silicon | Si
1) Used as an alloy in sheets for electromagnetic applications as it increases the electrical resistance
Melting point 2) Slight influence on the deoxidation
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 | S
1) It is added to steel in various quantities depending on the classes and the technological needs to improve the machinability
Melting point 2) Undesired from the point of view of the mechanical characteristics why it cause embrittlement
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| Te
1) Makes the sulphurs less plastic enabling an increased cutting speed and facilitating drilling operations
Melting point 2) Improves machining by up to 50% when combined with lead
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 | Sn
1) Contents of greater than 0,05% may make the steel brittle in hot machining, just like copper
Melting point 2) It is silvery-white, soft, malleable and ductile metal. Exposed surfaces form oxide film. Resists oxygen and water.
231.8 °C 3) When present in steel it is an undesirable impurity which gives rise to temper brittleness
Titanium | Ti
1) Prevents formation of austenite in steels with a high chromium content
Melting point 2) Reduces hardness and hardening in steels with an average chromium content
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 | W
1) Provides abrasion resistance for tool steels, reduces sensitivity to overheating
Melting point 2) Produces mechanical strength in parts for hot-working
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 | V
1) Produces fine grains
Melting point 2) Increases hardening
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 3) Has the power to absorb gases and is therefore also used as a “getter” or metallic absorbent
1860 °C 4) Since it cannot be altered by atmospheric agents it is used to produce corrosion resistant metal alloys