6.1 Flashcards
What is steel made from
Iron and Carbon
What does CRES stand for
Corrosion resistant steel
Low carbon steel
0.1-0.3%
Medium carbon steel
0.3-0.5%
High carbon steel
0.5-1.05%
Sulphur
Decreases ductility
And weldability
Manganese
Increases strength
Increase hardness
Silicon
Deoxidiser
Remove impurities
Phosphorus
Increases strength
Corrosion resistant
Nickel
Improved hardness
Greater impact stress
Chromium
Corrosion resistance
High temp strength
Molybdenum
Impact strength
Creep strength
Vanadium
Tensile strength
Yield strength
Titanium
Toughness
What is the primary hardening element in steel
Carbon
Tempuring
Decrease hardness and increase ductility and toughness.
Heat Above critical limit and let to cool and then quenched
Only works for high carbon
Hardening
Hearing above critical temp so carbon is dispersed evenly and uni formally. Then quickly quenched in oil water or brine.
What is the quickest quenching fluid
Bribe
What is the slowest quenching fluid
Oil
Annealing
Increases softness and relives stresses.
Heated 50f above critical limit and soaked at this time for a set period. Slowly cooled naturally or in sand. Soft ductile metal
What is normalising
Heated 100f above critical limit. And let to soak for a prescribed time and then cooled to room temp
Properties of stainless steel
Corrosion resistant
Strong and tough at high temp
Identified by three digit code
What are the disadvantages if steel
Hard to cut
Greater coefficient of expansion
Not suitable for high temp environment
Not heat treatable
Austensitic
More refined grain structure Non magnetic 200/300 series Cold worked Strain hardened Stabilising alloys
Ferrstitic
Soft
Magnetic
Hot heat treats me
Less workable
Marsinsitic series
400
Heat treatable
High carbon
Least corrosion resistant
What is used on landing gear in regards to steel
300m
Hydrogen embrittlement
Hydrogen will react with carbon causing methane making cracks
How to protect steel from corrosion
Cadmium bath Lead free paint Aluminium spray Chromium plate Nickel plate Silver plate (not in contact with Al)
Case hardening
Hardening the outer layer
When is case hardening suitable
Ferrous metals
Carburising
Hardening for low carbon steel
Pack carburising
Heating to 1700f whilst packed into a carbon rich material which. Penetrates the surface causing it to harden
Gas carburising
Using a carbon rich gas to penetrate surface
Liquid carburising
Hearing in a bath of sodium cyanide or barium cyanide
Flame-hardening
Heated using Oct-acetylene flame and then immediately cooled by quenching in a jet of water
Nitriding
Improved final surface and in an ammonia rich environment. The ammonia breaks the surface allowing nitrogen to penetrate
