Alloy Steel vs Titanium Submarine Hull

Presented by : Group 6 members

ALLOY STEEL

What is alloy steel….???????• Steels whose properties mainly attributed to the presence of one or more

elements other than carbon.• Content of alloying element exceed one or more of the following percentage

limit,

Manganese: 1.65%

Silicon: 0.6%

Copper: 0.6%

or when Aluminium, Boron, Chromium is up to 3.99%.• Some example of alloy steel: Cobalt, Columbium, Molybdenum, Nickel,

Titanium, Tungsten, Vanadium, Zirconium.• Two groups: high alloy steels and low alloy steels.• Physical properties: greater hardness, durability, corrosion resistance, or

toughness as compared to carbon steel.• To achieve this properties, alloys often require heat treatment.

Advantages of alloy steel

Greater hardenability

Less distortion and cracking

Greater ductility at high strength

Greater high temperature strength

Greater stress relief at given hardness

Better machinability at high hardness

High elastic ratio and endurance strength

Disadvantages of alloy steel

• Tendency toward austenite retention• Cost• Special handling• Temper brittleness in certain grades.

Purpose of alloying Strengthening of the ferrite Improved corrosion resistance Better hardenability Grain size control Greater strength Improved machinability Improved ductility Improved toughness Better wear resistance Improved cutting ability Improved case hardening properties etc. Improved high or low temperature stability.

Application of alloy steelMaterial AISI or SAE ApplicationCarbon

LowMedium

High

1 Nails, Screws, body parts, axles, rails, wheels, spring, tools, cutters

Nickel 2 Casting, boiler plates, structural steel

Nickel Chromium 3 Stainless steel, kitchen utensils, gears, shafts.

Molybdenum 4 Machinery, automobile parts, bolt and roller bearings, springs

Chromium 5 Hammers, Bearing, axles, gears

Chrome-Vanadium 6 Tools, spring and gears

Nickel, Chromium & Molybdenum 8 Machine tools

Manganese - Nickel, Chromium and Molybdenum 9 Parts for dies and molds

Titanium

What is Titanium….???? A chemical element with the symbol Ti and atomic number 22.

In its unalloyed condition, titanium is as strong as some steels, but 45% lighter.

Physical properties: low density and is a strong, lustrous, corrosion-resistant

(including sea water, aqua region and chlorine), transition metal with a silver

colour.

Useful properties: corrosion resistance and the highest strength-to-weight ratio of

any metal.

Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among

other elements, to produce strong lightweight alloys.

Titanium is extracted from its principal mineral ores via the Kroll process or the

Hunter process.

Advantages of Titanium It has the combined properties of being light and strong.

It is corrosive resistant

It can withstand high temperatures.

Very high plastic point.

Have high specific strength

Disadvantages of Titanium

• Expensive metal

• Expensive extraction method (Kroll process)

• Expensive to cast

• In some machined forms it is more brittle than steel,

although it has a higher tensile strength.

• It is hard to machine

Applications of Titanium

Pigments, additives and coatings

Aerospace and marine

Consumer and architectural

Industrial

Jewelry

Medical

Nuclear waste storage

Titanium ring

A fracture of the eye socket was repaired by stabilizing the fractured bones with small titanium plates and screws.

What is submarine hull…????

A light hull (casing in British usage) of a submarine is the outer non-watertight hull which provides a hydro dynamically efficient shape. The pressure hull is the inner hull of a submarine; this holds the difference between outside and inside pressure.

The metal for submarine hull

As a conclusion, titanium is suitable for making submarine hull. This is due to their high tensile strength to density ratio, high corrosion resistance, fatigue resistance, high crack resistance, and ability to withstand moderately high temperatures without creeping. Due to its high corrosion resistance to sea water, Titanium is used to make submarines largely out of titanium.

Thank you……..