Alloy steel
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Alloy steels differ from carbon steels in that they contain a high proportion of other
alloying elements.
Alloy steel is a type of steel alloyed with several elements such as molybdenum,
manganese, nickel, chromium, vanadium, silicon, and boron.
These alloying elements are added to increase strength, hardness, wear resistance, and
toughness.
The amounts of alloying elements may vary between 1 and 50%.
Alloy steels are classified into 2 types
1. According to the increasing proportion of alloying elements and also phase
change during heating and cooling as follows
o low alloy steels
o medium alloy steels
o high alloy steels
2. According to the number of alloying elements as follows:
o ternary - one element
o quaternary - two elements
o complex - more than two elements
 Chrome-vanadium steel- is a group of steel alloys incorporating carbon (0.50%),
manganese (0.70-0.90%), silicon (0.30%), chromium (0.80-1.10%), and vanadium (0.18%).
Some forms can be used as high-speed steel. Chromium and vanadium both make the steel
more suitable for hardening. Chromium also helps resist abrasion, oxidation, and
corrosion. Chromium and carbon can both improve elasticity.
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Effect of alloying elements- Chromium & Vanadium
o Chromium can improve the hardenability and wear resistance of steel.
Which helps to increase its corrosion and oxidation resistance. Vanadium can
refine the grain structure of steel, which increases its strength, toughness, and
wear resistance.
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Properties:
o Best for shock and impact loads.
o Used for internal combustion engine valve springs.
o It is medium carbon steel with chromium and vanadium added to increase its
hardness and tensile strength
o Good castability
o No additional roll forces are required with the vanadium alloyed steel
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Application:
o Used for springs that are required to withstand a large number of operating
cycles.
o Used for internal combustion engine valve springs (Temp. up to 220oC)
o Chromium vanadium is an alloy used to forge tools
o Used for high-stress applications.
o It is used for making axles and shafts of automobiles, aeroplanes and
locomotives.
o Used in surgical instruments and tools
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Advantages:
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Toughness enables it to withstand high fatigue and wear
Corrosion resistance
Can withstand high stresses
High tempering stability and wear resistance, thereby extending the life of the
tool.
Disadvantage:
o If the temperatures are higher, the surface of the material peels off what
inevitably leads to corrosion