Metals and Metal Alloys
What is ferrite?
A materials science term for iron, or a solid solution with iron as the main constituent. The component which gives
What is Austenite?
A metallic non-magnetic allotrope of iron that exists when iron is heated above 912 degrees and up to 1394 degrees, formed by diffusion of carbon atoms from cementite into ferrite
What is Martensite?
A very hard form of steel crystalline structure, the martensite is formed by rapid cooling (quenching) of austenite which traps carbon atoms
What happens when nickel is alloyed with steel?
Adds strength and hardness to steel and increases its yield strength, also slows the rate of hardening when steel is heat treated.
What are austenitic stainless steels?
Also referred to as the 200 & 300 series stainless steels, contain large percentages of chromium and nickel, and some manganese.
What is ferritic?
Ferritic stainless steel is a type of chromium alloy that has ferritic, body centered cubic crystal structures
What is pig iron?
The intermediate product of smelting iron ore with coke, usually with limestone as a flux. High carbon content which makes it very brittle
What happens when chrome moly is alloyed with steel?
The most commonly used alloy in aircraft, it machines readily, is easily welded and responds well to heat treatment
What is martensitic stainless steel?
The 400 series of stainless steel, Alloyed with chromium only and therefore are magnetic.
What is 18-8 Stainless steel?
The corrosion resistant steel most used in aircraft construction. Contains 18% Chromium and 8% Nickel, One of its distinctive features as its strength may be increased by cold working
What happens when vanadium is alloyed with steel?
When combined with chromium it produces a strong tough ductile steel alloy.
What is martensitic?
400 series of stainless steel, alloyed with iron, chromium and carbon
What is stainless steel?
A classification of corrosion resistant steels that contain large amounts of chromium and nickel. Their strength & Resistance to corrosion makes them well suited for high temp applications
What is an austenitic alloy?
Austenitic alloys are non-magnetic metal alloys primarily used in the production of stainless steel, they contain a high percentage of nickel and chromium, they are very resistant to corrosion (Used to make highly stressed parts such as turbine discs)
What is cementite?
Cementite (Or iron carbide) is a chemical compound (Fe3C) It is a hard brittle material, more important in metallurgy
What happens when tungsten is alloyed with steel?
Has an extremely high melting point. Retains hardness at elevated operating temperatures
What happens when silicon is alloyed with steel?
It acts as a hardener, when used in small quantities it also improves ductility
What happens when Chromium is alloyed with steel?
It increases strength and hardness as well as improves its wear strength and corrosion resistance. Commonly used in bearings
What happens when phosphorus is alloyed with steel?
It raises the yield strength of steel and improves low carbon steels resistance to atmospheric corrosion, too high amounts cause the alloy to become brittle when cold.
What happens when molybdenum is alloyed with steel?
Most widely used alloying element, reduces grain size of steel and increases both impact strength and elastic limit.
What happens when Nickel Chromium is alloyed with steel?
Nickel toughens steel and chromium hardens it, therefore when both elements are alloyed it gives desirable characteristics for use in high strength structural applications
What is ferritic stainless steel?
Primarily alloyed with chromium but many also contain small amounts of aluminium, however they contain no carbon and therefore do not respond to heat treatment.
What are alloying agents?
Small quantities of elements added to a base metal to form an alloy.
What is carbon steel?
Steel can be heat treated which allows parts to be fabricated om am easily formidable soft state, if enough Carbon is present the alloy can be hardened to increase strength, wear and impact resistance
Where each steel alloy could be used in aircraft or component construction
Tungsten Typically used for breaker contacts in magnetos and for high speed cutting tools. Vanadium Most wrenches and ball bearings are made of chrome-vanadium steel. Molybdenum Used in high strength structural members and cylinder barrels Nickel-Chromium Used for forged or machined parts requiring high strength, ductility, shock resistance and toughness. Chromium Used in balls and rollers of antifriction bearings Chrome-molybdenum Chrome molly's toughness and wear resistance make it a good material for engine cylinders and other highly stressed parts Nickel SAE 2330 steel contains 3 percent nickel and 0.03 percent carbon, and is used in producing aircraft hardware such as bolts, nuts, rod ends and pins
What is Gamma iron?
known as Austenite
What is pearlite?
pearlite is a two phased, layered structure composed of alternating layers of ferrite and cementite that occurs in some steels and cast irons
