Metallurgy Flashcards
What are metals that have iron as the major ingredient and are usually magnetic?
Ferrous metals
What are the most common ferrous metals?
Carbon steel and cast iron.
What are metals that do not have iron in large enough amounts to have any major influence on the properties of the metals, or no iron at all?
Non-ferrous metals.
How can you visually distinguish between hot rolled steel and cold rolled steel?
Hot rolled steel has a black mill scale.
What can you use to identify metals with the same outward appearance, such as aluminum and zinc die-cast?
Weight identification.
Identifying an object as a casting by its rough outer surface is an example of what type of identification?
Identification by texture.
Identifying an object by casting marks or by its intricate design is what type of identification?
Shape identification.
Identifying an object as a formed product by its solid metal, smooth outer surface is what type of identification?
Shape identification.
The ability of a metal to resist penetration and plastic deformation is what mechanical property?
Hardness.
The ability of a metal to be stretched permanently without breaking is what mechanical property?
Ductility.
The ability of metal to withstand shock and impact without breaking or shattering is what mechanical property?
Toughness.
The ability of a metal to withstand pull without breaking is what mechanical property?
Tensile strength.
What mechanical property measures the ease with which you can cut and shape a metal?
Machinability.
What property measures how easily a metal will fracture if bent sharply or struck?
Brittleness.
What property measures how much squeezing force a metal can take before it fails?
Compression strength.
What is yield strength?
The force at which a weld
specimen starts to pull apart.
What does elongation measure?
How much a metal will stretch
before it breaks.
What will examining grain size tell you about a known metal?
Brittleness.
Tensile strength.
Heat treatment.
Ductility.
Angle iron, channel iron or beams are an example of what type steel?
Structural steel.
In specifying sizes of C shapes, what does the nominal size refer to?
The distance from outside flange face to outside flange face.
What would an imperial C shape size of C6 x 10.5 refer to?
Nominal size 6 inches and 10.5 lb/ft.
When specifying an L shape, what do the three numbers refer to?
Both leg lengths and thickness.
When specifying a hollow structural section, what do the three dimensions refer to?
Both outside dimensions and wall thickness.
Why is hot-rolled steel made a little larger than its nominal size?
So it can be finish machined to the nominal size if necessary.
Why should you leave a generous finishing allowance when machining cold-rolled steel?
Cold-rolling sets up internal stresses, which causes cold-rolled steel to warp during machining.
What is the process of making wire or tubing by pulling a steel rod through one or more dies?
Cold-drawing.
What is any tubular product that is produced in a size commonly used for piping systems?
Pipe.
What is any tubular product, other than pipe, that includes square, rectangular, and round shapes?
Tubing.
For pipes under 12 inches in diameter, what does the nominal size refers to?
Refers to a standardized outside diameter that, given a standard wall thickness, would provide an inside diameter roughly equal to the nominal size.
What is the nominal size of pipes over 14 inches in diameter?
The nominal size equals the outside diameter.
For tubes, what does the nominal size refer to?
The nominal size equals the outside diameter of the tube.
How is sheet steel size specified?
By thickness, width, length and type.
How do you determining the carbon content for carbon and alloy steels?
The last two numbers of its ID number give the decimal percent of carbon in the steel.
What is the carbon content of 4140 alloy steel?
The carbon content is 0.40%.
What is the carbon content of low carbon steel?
0.02% to 0.30%.
Can low carbon steel be hardened?
No, only case hardened.
What is the carbon content of medium carbon steel?
0.30% to 0.60%.
What type of carbon steel are hand tools typically made from?
Medium carbon steel.
What is the carbon content of high carbon steel?
Over 0.60%.
What type of steel are cutting tools like taps and drills made from?
High carbon steel.
Why does high strength low alloy steel not rust?
The rust that forms on the outer skin of this steel is impervious to water and prevents the steel from rusting further.
Is tool steel meant to be hardened before or after machining?
Tool steel is hardened after machining.
During fusion welding what effect does the heating the steel have on its properties?
It ruins the heat treatment.
What metal is stainless steel alloyed with?
Chromium.
What qualities does using chromium add when used as an alloy with carbon steel?
Corrosion resistance.
Improved heat treatment.
What metal, other than chromium, is austenitic stainless steel alloyed with?
Nickel.
What are some properties of austenitic stainless steel?
Excellent strength.
Very corrosion resistant.
Cannot be hardened.
Is not magnetic.
What is ferritic stainless steel alloyed with?
Chromium.
What are some properties of ferritic stainless steel?
Resists corrosion.
Lacks strength.
Cannot be hardened.
What is martensitic stainless steel alloyed with?
Chromium.
What are some properties of martensitic stainless steel?
Can be hardened.
Not as corrosion resistant.
What is brass a mixture of?
Copper and zinc.
What are some properties of brass?
Corrosion resistant.
Easy to machine.
Harder and stronger than aluminum.
Tougher than bronze.
What is bronze made of?
Usually copper and tin.
Is bronze usually harder than brass?
Yes.
What is the process of heating and cooling a metal to change one or more of the metal’s properties?
Heat treatment.
What is the structure of soft steel?
Pearlite.
What does pearlite consist of?
Layers of ferrite (pure iron) and cementite (a carbide compound formed from iron and carbon).
What is the structure of hardened steel?
Angular, needle like crystals called martensite.
When is austenite formed?
Austenite is formed when pearlite is heated to a red heat, causing the layers of ferrite and cementite to begin to dissolve into each other.
How is steel hardened?
It is heated until it changes to austenite.
It must be quenched (cooled rapidly) to form martensite.
What carbon content does steel need in order to be hardened?
0.20%
How does hardening temperature vary with the carbon content of steel?
Generally, the higher the carbon content, the lower the hardening temperature.
When heating with a torch, what colour is the workpiece when the hardening temperature is reached?
Cherry red.
After heating if quenching does not happen immediately, what happens to the steel?
It reverts to pearlite instead of martensite.
If a steel has a high carbon content, how should it be quenched?
The piece should be gently cooled.
When quenching a long and straight workpiece, how should it be put into the quenching medium?
Submerge the workpiece completely while holding it straight up and down. Move it in a figure eight motion.
To remove the brittleness and internal stresses of freshly hardened steel, what must be done?
The steel must be tempered.
What happens to hardness as the tempering time and temperature increases?
The hardness decreases.
To achieve a more controlled temper, what mediums can the workpiece be heated in?
Oil, sand, salt, or lead bath.
What is used to make a hardened workpiece soft again?
Annealing.
What happens to the structure of the steel when it is annealed?
It is converted from martensite to pearlite.
What is the process that eliminates strains and restores the proper grain structure of the steel?
Normalizing.
What type of hardness testing determines the hardness of a specimen by measuring how far you can force a penetrator into the specimen?
Rockwell hardness testing.
Why should you not use the steel ball penetrator on hardened steel?
It will flatten the ball and ruin it.
What type of hardness testing system uses a hydraulic press to force a round penetrator into ferrous or non-ferrous specimens?
Brinell hardness testing.
How do you perform a tensile test?
Pull the specimen apart until it breaks.
When chip testing, what types of metal give smooth, continuous chips?
Aluminum, copper, or low-carbon steel.
What do the chips look like when chip testing high carbon steel like cast iron?
The steel becomes more difficult to cut and the chips become smaller and more brittle.
What is a quick and fairly accurate test for identifying a metal by studying the spark stream produced during grinding?
Spark testing.
What is spark testing mainly used for?
To test for carbon content in steels and to distinguish between a cast steel and a cast iron.
Sparks that are bright, long, straight, and yellowish in colour, with very little branching and few carbon bursts identify which metal?
Low carbon steel (mild steel).
Sparks that are a darker yellow-orange colour and burst nearer to the wheel, with some sparks following around the wheel identify which metal?
High carbon steel.
A spark stream that produces many bursts that are red coloured near the grinder and orange-yellow further out identify which metal?
Cast iron.
Sparks that are orange with very little branching and end up ball-shaped identify which metal?
High-speed steel.
What is a test which tests the resistance of a metal to cutting or abrasion?
File testing.
What is the best file to use for file testing?
A sharp 6 inches or 8 inches three-corner file.
How do you perform a metal flame test?
Heat a small area of the specimen to a molten state using an oxyfuel flame.
What can you observe from a flame test?
Speed of melting.
Changes in colour.
Appearance and action of the slag.
Appearance of the molten puddle.
Action of the puddle under the flame.
How does magnesium react to the flame test?
Magnesium sparks and flashes into flame violently.
What is the report that contains information about a metal such as chemical composition, physical properties, mechanical properties, and specifications used for filler metals?
The mill test report.
When cutting a piece from a plate what should be retained or transferred?
Any ID marks such as the heat number.
What are the tags that are attached to bundles of material being shipped?
Metal specification tags.
What is the process used to take hardened high carbon steel to a tougher hardness called?
Tempering.
What quality do we look for when we make items out of zinc?
Manufacturing ease.
What quality do we look for when making items out of magnesium?
Lightness.
Which test would you use to determine if a metal is polished steel or stainless steel?
Magnet test.
Which of these processes could you use to harden medium carbon sprocket teeth for wear resistance?
Flame hardening.
What are the three main types of stainless steel?
Austenitic, martensitic, and ferritic.
What process heats steel slightly above the upper critical temperature and then slowly cools it to relieve stresses?
Normalizing
What process would you apply to a freshly welded carbon steel bandsaw blade?
Annealing.
