Metallurgy Flashcards
Learn about lattice structures, alloys and heat control.
The science that explains the properties, behavior, and internal structure of metals is called what?
Metallurgy
Electrical and thermal conductivity, hardness, strength, ductility and toughness are all:
Metallurgical properties
The ability to withstand impact is:
Toughness
Fracture toughness results will often be expressed in terms of:
Breaking energy
As hardness is increased, _______ is decreased.
Ductility
As temperature increases during tempering, what property decreases?
Hardness
Rockwell, Vickers, Knoop and Brinell are tests used to determine what metallurgical property?
Hardness
The ability to deform without failing is:
Ductility
As temperature decreases, which property also decreases?
Ductility
Aluminum, copper and soft steels are high in what metallurgical property?
Ductility
Ductility can be expressed in terms of:
Percent elongation and/or reduction of area
The absence of ductility cannot be measured itself, but the metallurgical property is called:
Brittleness
The tendency to deform very little before failing suddenly, describes:
Brittleness
As a materials hardness increases, does its strength increase?
Yes
The ability to resist crushing is:
Compressive strength
The ability to withstand indentation is:
Hardness
Files and drill bits are high in what metallurgical property?
Hardness
Impact wrenches, jack hammers and connecting rods are high in what matellurgical property?
Toughness
Lifting tools, come-a-longs and bearing pullers are high in what metallurgical property?
Tensile strength
The ability to withstand a static load is:
Strength
The ability of a material to return to its original form after stress is removed is called:
Elasticity
The ability of a material to be cyclically loaded without failing is called:
Fatigue strength
Deformation caused by stress is called what?
Strain
A material performs elastically until it passes its yield point. After its yield point has been reached, the material performs:
Plastically
The property expressed in terms of endurance limit is:
Fatigue strength
The point on a stress-strain curve where the material changes from elastic to plastic is called its:
Yield point
When atoms or molecules group together in a neat, orderly formation, they form what?
Grains (crystals)
Larger or smaller, which grain size exhibits greater strength?
Smaller
Are course grains weaker than small grains?
Yes
What is the lower transformation temperature of steel?
1,333 F
A graph showing the phases and temperatures at which alloys exist is called what?
Phase diagram
What does PWHT stand for?
Post Weld Heat Treatment
Which type of PWHT (post weld heat treatment) results in the softest carbon steel?
Annealing
The type of PWHT (post weld heat treatment) where the material is heated above the lower transformation temperature, held for a certain amount of time, and slow cooled in a furnace is:
Annealing
Which type of PWHT (post weld heat treatment) softens the metal more than normalizing?
Annealing
The type of PWHT (post weld heat treatment) where the material is heated above the lower transformation temperature, held for a certain amount of time, and cooled in still air is:
Normalizing
The type of PWHT (post weld heat treatment) where the material is heated to less than the lower transformation temperature and slow cooled:
Stress relieving
Which types of PHWT (post weld heat treatment) involve heating the metal to a temperature between 1500 - 1800 F?
Normalizing and annealing
The PWHT (post weld heat treatment) that follows quenching and restores some of the metal’s ductility is:
Tempering
Brine, water or oil may be used for what PWHT (post weld heat treatment) technique?
Quenching
The primary goal of PWHT (post weld heat treatment) is to relieve what?
Residual stress
What technique for controlling distortion does not help reduce residual stress?
External restraint
What two factors determine if a material requires preheat?
Carbon equivalent and thickness
Use of preheat results in:
A slower cooling rate and wider HAZ (heat affected zone)
The capacity of a material to be welded into a specific, suitably designed structure performing satisfactorily in the intended service is called:
Weldability
Carbon equivalent is used to determine which property?
Weldability
Low-carbon steel has a carbon content of _____ % or less.
0.30%
Medium-carbon steels have a carbon content between 0.30% and ______%.
0.55%
A pure substance composed of a single material is called what?
An element
Steels that are primarily made of iron are called:
Ferrous
A material made up of two or more elements, at least one of which is a metal, is called what?
An alloy
Which alloying element has the greatest effect on steel?
Carbon
Which alloying element gives carbon steel the best corrosion resistance?
Chrome
What two ways can atoms of an alloy be incorporated into the original metal structure?
Substitutionally or interstitially
The type of alloying where atoms of the alloy take the places of original atoms in a metals structure is known as:
Substitutional alloying
The type of alloying where atoms of the alloy are dispersed between the original structure is known as:
Interstitial alloying
Steels alloyed with carbon and only a low percentage of silicon and manganese are known as:
Plain carbon steels
The melting point of steel is approximately:
2,500 F
Time-temperature-transformation (TTT) charts show what?
Grain growth
Carburizing, nitriding and localized heating are types of what?
Surface hardening
The surface-hardening technique that impregnates the outer surface of steel with carbon is called:
Carburizing
In the four digit numbering system for steels, what do the last two numbers designate?
Percentage of carbon
In the four digit numbering system for steels, what do the first two numbers designate?
Major alloying elements
For a steel designated 4140, what is its carbon content?
0.40%
The process of removing dissolved oxygen from molten metal is called:
Deoxidation
The energy applied to the work-piece during welding is called:
Heat input
The calculation for heat input is:
(Amps x Volts x 60) / Travel Speed = J/in
Using a smaller diameter electrode and increasing travel speed will have what effect on heat input?
Heat input will decrease
An increase in amperage and voltage will have what effect on heat input?
Heat input will increase
The unit for measuring work or heat energy is called a:
Joule
Expansion and shrinkage during welding causes what two stresses?
Residual stress and distortion
Relieving residual stress in a weld by using impact blows is called:
Peening
Can stress relieving be accomplished by mechanical means?
Yes
Vibratory stress relief is another term for what mechanical stress relief?
Peening
The portion of base metal which has not been melted, but whose mechanical properties or microstructure has been altered by the heat of welding is called:
Heat-affected zone (HAZ)
HAZ stands for:
Heat affected zone
All matter contains heat down to absolute zero. What temperature is absolute zero?
-460 F
Protons, neutrons and electrons form what?
Atoms
What is the smallest part of an element?
An atom
Atoms changing position while a material is in its solid state is called:
Diffusion
Atoms combine to form what?
Molecules
Carbon steel exists in what unit cell arrangement at room temperature?
BCC
body centered cubic
Which microstructure is the hardest?
Martensite
The unit cell arrangement with the closest arrangement of atoms is:
HCP
hexagonal closed packed
The three types of unit cell arrangement for metals are:
BCC, FCC, and HCP
body centered cubic, face centered cubic, and hexagonal closed packed
Which crystal lattice structure is shown here?
BCC
body centered cubic
Which crystal lattice structure is shown here?
FCC
face centered cubic
Which crystal lattice structure is shown here?
HCP
hexagonal close packed
Which microstructure is shown here, characterized by a fine, needle-like apprearance?
Martensite
Rapid cooling of carbon steel from the austenitic range will result in the formation of:
Martensite
Slow cooling of steel helps produce a soft, ductile microstructure which has a lamellar appearance when viewed under a microscope. This structure is:
Pearlite
Which microstructure is shown here, characterized by a lamellar appearance?
Pearlite
Which microstructure is shown here, the result of combining two other microstructures?
Ferrite-pearlite
Which microstructure is shown here, characterized by being mostly white with only small carbon deposits in black.
Ferrite
The maximum temperature that a metal reaches during welding is called:
Interpass temperature
Organic compounds like water, oil and grease all contain what element that can be detrimental to welding?
Hydrogen
Which alloying element acts as a deoxidizer?
Silicon
Which alloying element improves corrosion resistance?
Chrome
Which alloying element increases toughness and ductility?
Nickel
The three states of matter are:
Liquid, solid and gas
A wider HAZ (heat affected zone), a slower cooling rate and smaller grain size are all benefits of what?
Preheat
Metals like aluminum, brass and copper that do not have iron as their base are called what?
Non-ferrous
A steel designated 4130 has a carbon content of what?
0.30%
Quenching a material from temperatures above the lower transformation temperature will result in what microstructure?
Martensite
What crystal lattice structure can be described as a cube with an atom at each corner and a single atom in the center of the cube?
BCC
body centered cubic
What lattice structure can be described as a cube with an atom at each corner and an atom in the center of each face of the cube?
FCC
face centered cubic
Does molten steel have a crystal lattice structure?
No
What happens to matter as it is heated?
It expands
Stainless steels have a minimum chromium content of:
12%
Ferritic, martensitic, austenitic and precipitation hardened are all types of:
Stainless steels
“300” series stainless steels is what grade?
Austenitic
“400” series stainless steels are what grade?
Martensitic
Which state of matter has the least amount of energy?
Solid
The ability of a material to absorb energy is:
Toughness
Metals that are strongly attracted by a magnet are called what?
Ferromagnetic
What kind of metal is classified 6061-T6?
Aluminum
What does ‘HAZ’ mean?
Heat Affected Zone
What is the HAZ?
The base metal adjacent to the weld that was heated to a high temperature but not melted
