Materials Science Quiz 2 Flashcards
Metals or alloys having high percentage of iron
These Materials are used where high strength is required at relatively low cost
Ferrous Materials
3 types of ferrous materials
- Steel - Alloy of iron and carbon (1.5 %)
- Cast Iron - Alloy of iron and carbon (4.5%)
- Wrought Iron - Almost pure Iron (99.9%)
Classification of Steels
- Low Carbon Steel
- Medium Carbon Steel
- High Carbon Steel
Classification of Iron
- Grey Cast Iron
- White Cast Iron
- Malleable Cast Iron
- High Duty Cast Iron
- Alloy Cast Iron
Metals Other than Iron
In Pure Form, they are used with other materials in order to obtain a certain property like corrosion resistance, ductility, hardness, etc.
Non-Ferrous Materials
Deformation of temperature high enough for recrytallization
Large Deformations
Metal Fabrication (Hot Working)
Deformations below recrystallization
Strain Hardening occurs
Small deformations
Metal Fabrication (Cold Working)
Types of Forming (Metal Fabrication)
- Forging
- Hammer Forging
- Press Forging
- Drawing
- Rolling
- Extrusion
Deformation process in which work thickness is reduced by compressive forces exerted by two opposing rolls
Rolling
A cold working process in which the work piece is pulled through a tapered hole in a die so as to reduce its diamater
Drawing
Forming a preheated workpiece by using a force created by hydraulically driven ram causing the metal to be squeezed into the die cavity by the static pressure
Press Forging
a process used to create an objects of a fixed cross-sectional profile. A material is pushed through a die of the desired cross-section
Extrusion
the process of producing metal/alloy component parts of desired shapes by pouring the molten metal/alloy into a prepared mould and then allowing the metal/alloy to cool and solidify
Casting
a process of using sand as the primary material to mold various metallic products
Sand Casting
includes wax pressure, wax repair, group tree, dip slurry, wax melting, casting metal liquid and post processing process
Investment Casting
3 stages of investment casting
Stage 1 - Mold formed by pouring plaster of paris around wax pattern
Stage 2 - Wax is melted and then poured from mold-hollow mold cavity remains
Stage 3 - Molten Metal is poured into mold and allowed to solidify
A metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity
Die Casting
A process of joining similar and dissimilar metals or other material by application of heat
Welding
Five Major factors of weldability
- Melting Point
- Thermal Conductivity
- Thermal Expansion
- Surface Condition
- Change in microstructure
Welding Classification
- Plastic Welding - piece of metal is heated to plastic state then forced together by external pressure
- Fusion Welding - material is heated together into molten state then solidified
- Cold Welding - applies pressure to the joint that result in diffusion or inter-surface molecular fusion
a welding process, in which two work pieces are joined under a pressure providing an intimate contact between them and at a temperature essentially below the melting point of the parent material
Solid State Welding
Solid state welding Advantages
- Weld is free from microstructure defects
- Mechanical Properties of the weld are similar to the parent material
- No consumable materials (Fillers, fluxes) are required
- Dissimilar objects may be joined
A process, in which low carbon steel parts are heated to about 1000 C ( 1800 F) and then forged (Hammered)
Solid state welding type - Forge Welding
Forge Welding advantages
- Good quality welding is obtained
- Parts of intricate shape can be welded easily
- No filler material is required
Forge Welding disadvantages
- Only low carbon steel may be welded
- High level operating skill is required
- Slow welding process
- weld may be contaminated by the coke used in the heating furnace
a process, in which two work pieces are joined together at room temperature and under a pressure, causing substantial deformation of the welded parts and providing intimate contact between the welded surfaces
Solid state welding type - Cold Welding
in which two cylindrical parts are brought in contact by a friction pressure when one of them rotates
Solid state welding type - Friction Welding
In which parts are metallurgical bonded as a result of oblique impact pressure exerted on them by a controlled detonation of explosive charge
Solid state welding type - Explosive Welding
Explosive Welding Advantages
- Large surfaces may be welded
- Low cost and simple process
- Surface preparation is not required
Explosive Welding disadvantages
- Brittle materials can not be processed
- Thickness of Fyler plate is limited
- Safety and security aspects of storage and using explosives
In which pressure is applied to two work pieces with carefully cleaned surfaces and at elevated temperature below the melting point of the materials
Solid state welding type - Diffusion welding
Diffusion welding advantages
- Dissimilar materials may be welded
- High quality welding is obtained
- No limitation in thickness of work pieces
Diffusion welding disadvantages
- Time consuming process with low productivity
- Very thorough surface preparation is required
- Relatively high investment in equipment
In which two work pieces are bonded as a result of a pressure exerted to the welded parts combined with application of high frequency
Solid state welding type - Ultrasonic welding
Ultrasonic welding advantages
- Dissimilar metals can be joined
- Very low deformation of the work pieces surface
- High quality weld is obtained
- The process may be integrated into automated production lines
- Moderate operator skill level is enough
Ultrasonic welding disadvantages
- Work pieces may bond to the anvil
- Only small and thin parts can be welded
a fusion welding process in which high velocity electron beam is used to join metals together
Electron beam welding
It is used to generate, accelerate, and align the electron beam in a desired direction and spots on the w/p
Electron gun
Parts of electron gun
- Cathode
- Anode
- Grid Cup
- Focusing unit
Electron beam welding parts
- Electron gun
- Power supply
- Vacuum Chamber - composed of diffusion pump and mechanical pump
- Work Handling devices
Electron beam welding advantages
- High welding speed
- Welding of dissimilar metal can be done
- High weld quality and precision
- Less operating cost
- Materials with high welding temperature can be welded easily
- Less distortion due to less affected heat zone
- Cost of cleaning is negligible
Electron beam welding disadvantages
- Cost of equipment is very high
- High skill operator is required to operate it
- High vacuum is required
- Due to operation if vacuum, large jobs can not welded
- High safety measures are need to work with it
Electron beam applications
- Aerospace industry, jet components
- Power generation industry
- space industry to build titanium tanks and sensors
- It is used in automobile industry to manufacture transmission system
- It is used in electrical and electromechanical industry to manufacture parts of copper structure
- Nuclear industry and medical industry
a type of liquid state welding process in which fuel gases burns to generate heat which is further used to melt interface surfaces of welding plates which are held together to form a joint
Gas welding
Gas welding advantages
- It is easy operate and dose not required high skill operator
- Equipment cost is low compare to other welding process
- it can be used at site
- Equipment’s are more portable than other type of welding
Gas welding disadvantages
- It provides low surface finish, This process needs finishing after welding
- Have large, affected heat zone
- Higher safety issue due to naked flame of high temperature
- It is suitable only for soft and thin sheets
- Slow metal joining rate
- No shielding area which causes more welding defects
a liquid state welding process in which the metal to metal joint created in liquid or molten state
Resistance welding
it is a simplest type of resistance welding in which the work pieces are held together under pressure of anvil face
Resistance welding - spot welding
Annealing process of heating the metal slightly above the critical temperature
Annealing
Annealing advantage
- It softens the metal
- Enhances and improves the machinability of metal
- Increases ductility
- It enhances toughness of metal
