Common Alloy Steels

Some of the popular alloy steels are :

• Silicon steel
• Nickel steel
• Chrome-Vanadium steel
• Chrome-Molybdenum steel
• Manganese steel
• Vanadium steel
• Silicon-Manganese steel
• Chrome-Nickel steel
• Molybdenum steel
• Chrome steel
• Tungsten steel
• Cobalt steel

1. Silicon Steel

• The composition of silicon steel is as given below:
  C : 0.10%
  Mn : 0.60%
  Si : 1.00%
• Silicon imparts strength and fatigue resistance and improves electrical properties of steel.
• Many bridges have been built of what is called Silicon Structural Steel. This is stronger than carbon steel of equal ductility.

2. Silicon-Manganese Steel

• The composition of silicon-manganese steel is as given below:
  C : 0.40-0.55%
  Si : 0.04-1.8%
  Mn : 0.9-1.0%
• Such steels are used for springs in the hardened and tempered condition (55 Si 2 Mn 90 steel), and for making punches and chisels.

3. Nickel Steel

• The composition of Nickel steel is as given below:
  C : 0.35%
  Ni : 3.5%
• Addition of nickel to structural steel results in an increase of strength, without a proportionally great decrease of ductility.
• Nickel steels are used for storage cylinders for liquefied gases and for other low temperature applications.
• Other uses of nickel steels are for heavy forgings, turbine blades, highly stressed screws, bolts and nuts (40 Ni 3 steel).

4. Chrome-Nickel Steel

• The composition of chrome-nickel steel is as given below:
  C : 0.35%
  Ni : 1.25%
  Cr : 0.60%
• Chrome-nickel steel will have, after heat treatment, almost the same strength and ductility as 3.5% Nickel steel which has also been heat-treated, but it will not cost as much.
• Chrome-nickel steels combine the effect of nickel (in increasing the toughness and ductility) and chromium (in improving hardenability and wear resistance).

5. Chrome-Vanadium Steel

• The composition of chrome-vanadium steel is as shown below:
  C : 0.26%
  Cr : 0.92%
  V : 0.20%
• Chromium and vanadium are added to low alloy steel to increase its hardenability and to impart a grain structure that is finer than that of the standard chromium low-alloy steels.
• Chrome-vanadium steel is used for making axles and shafts of automobiles, aeroplanes and locomotives.

6. Molybdenum Steel

• The composition of molybdenum steel is as shown below:
  C : 0.35%
  Mo : 0.76%
• Molybdenum steel, when heat-treated, produces a structural steel which has an increased elastic limit without correspondingly decreased ductility. Molybdenum improves hot hardness and strength of steel. Molybdenum steels are less affected by temper brittleness.
• Molybdenum steels are used for making :
  • Aircraft landing gear
  • Coil and leaf springs
  • Transmission gear
  • Pressure vessels, etc.

7. Chrome-Molybdenum Steel

• The composition of chrome-molybdenum steel is as shown below :
  C : 0.35%
  Cr : 1.06%
  Mo : 0.36%
• Chrome-molybdenum steel has not as good as combination of strength and ductility as nickel, chrome-nickel and chrome-vanadium steels, but it is quite easy to roll and draw into tubes, to fabricate, and to weld, so that it is very popular for airplane structural parts.

8. Chrome Steel :

• The composition of chrome steel is as shown below:
  C : 0.36%
  Cr : 0.57%
• Chromium intensifies the effect of rapid cooling on steel. Therefore chromium is used only in steels which are to be heat-treated.
• Chromium forms carbides and thus gives high hardness and good wear resistance. In addition, chromium increases tensile strength and corrosion resistance of low alloy steels.

9. Manganese Steel : 

• Manganese low alloy steels are characterized by:
  Mn : 1.6 – 1.9%
  C : 0.18 – 0.48%
  Si : 0.2 – 0.35%
  S and P < 0.040% each
• Manganese increases hardness and tensile strength. A secondary effect is an increased resistance to abrasion. The steel also withstands the shock test excellently.
• Manganese steels are used for making power shovel buckets, grinding and crushing machinery, railway tracks, etc.

10. Tungsten Steel

• Tungsten low alloy steels are tool steels containing approximately 2% tungsten, 1.70% chromium and 0.50% carbon. This is hard tough tool steel that is commonly used for making cutting tools.
• Tungsten forms carbides and prevents softening of the alloy at high temperatures.
• The tungsten steel may contain upto 15% tungsten. Tungsten steel is used for making high speed cutting tools and permanent magnets.

11. Vanadium Steel

• Vanadium is one of the most powerful scavengers that can be added to liquid steel for the special purpose of removing oxygen. Vanadium has the effect of increasing the strength and hardness of the metal. It produces a very small grain size.
• Except for castings, vanadium is seldom used as the sole alloying element in steel. It is used together with chromium and other elements when high strength and anti-fatigue properties are essential, as in springs, gears, shafts and heavy forgings.

12. Cobalt Steel 

• Cobalt tool steels are used where high frictional heat is developed. Cobalt imparts additional red hardness to steel and cutting ability of tool is maintained at elevated temperatures.

MADE EASY

MADE EASY is a well-organized institute, complete in all aspects, and provides quality guidance for both written and personality tests. MADE EASY has produced top-ranked students in ESE, GATE, and various public sector exams. The publishing team regularly writes exam-related blogs based on conversations with the faculty, helping students prepare effectively for their exams.