Metallurgy Flashcards

1
Q

What is the definition of metal

A
  • it is a solid at room temp
  • it is opaque(not transparent)
  • it conducts heat and electricity
  • it reflects light when polished
  • it expands when heated and contracts when cooled
  • it has a crystal structure
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2
Q

What is ferrous metals?

A

Iron is the major ingredient and are usually magnetic.

They are alloys of iron and steel

Very high carbon steel is used to make punches, dies, sheer blades and cutting tools often called tool steels or high speed steels

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3
Q

Describe non ferrous metals?

A

Do not have iron in large enough amounts to have any major influence.

Aluminum, magnesium, zinc, copper, lead and brass are examples of non ferrous metals

Nickel is a-bit different because it is non ferrous but still magnetic.

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4
Q

What is the most practical method for identifying metal?

A

Visual appearance
Texture
Colour

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5
Q

What is the visual difference between hot and cold rolled steel

A

Hot rolled steel has black millscale on it

Cold rolled had shiny smooth surface

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6
Q

An object with rough surface is an indication that it is a?

A

Cast

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7
Q

If a solid metal has smooth outer surface it has been?

A

Formed

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8
Q

What are the most important properties to consider for metals are?

A

Hardness(ability for metal to resist penetration

Ductility (the ability of the material to be stretched without breaking)

Toughness (the ability of the metal to withstand shock)

Tensile strength (the ability of a metal to be pulled without breaking)

Machinability (measures the ease you can cut and shape the metal)

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9
Q

What method is stronger in structural steel? Hot rolling or welded?

A

Hot rolling

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10
Q

What steel is most common in building steel?

A

Carbon steel

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11
Q

What is structural steel?

A

Metal shaped to a certain profile

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12
Q

What do these numbers represent? C6x10.5

A

C=channel
6=size (outside flange to outside flange)
10.5=weight (lb/ft)

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13
Q

What do these numbers represent?

L3x3x1/4

A

Equal angle iron leg
L=angle iron
3= leg length
1/4= thickness

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14
Q

What do these numbers mean?

L8x6x1

A

Unequal angle iron

Longest leg always written first

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15
Q

How is HSS classified?

A

Outside dimensions and wall thickness

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16
Q

Why is hot rolled steel made slightly bigger?

A

So it can be machines finished to the nominal size

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17
Q

What is cold drawn wire tubing?

A

The act of pulling steel rod through one or more dies. This is used to make wire or tubing.

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18
Q

What is the difference between sheet steel and steel plate?

A

Thickness (sheet steel is up to 28 to 18 gauge. Steel plate is over 3/16th)

Width (sheet metal 36,48,60, and 72” steel plate 48-96”

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19
Q

What are the 7 classifications of metals?

A
Carbon steel 
Alloy steel
Tool steel
Stainless steel
Aluminum and it’s alloys 
Copper and it’s alloys
Cast iron
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20
Q

What is SAE?

A

Society of automotive engineers

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21
Q

What is AISI?

A

American iron and steel institute

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22
Q

Using the aisi-sae numbering system what do the numbers mean?

4140

A

41=type of steel

40=amount of carbon

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23
Q

What is the difference between carbon steel and alloy steel

A

Carbon steel contains carbon and iron

Alloy steel contains significant elements other then iron and carbon

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24
Q

What is tool steel?

A

High quailing steel used for cutters, tools, does, molds and jigs

Meant to be hardened after machining

25
Q

What is stainless steel

A

Alloyed with lots of chromium. More corrosion resistant

26
Q

What are the primary advantages of aluminum?

A

Lightweight, high machinable and corrosion resistant

27
Q

What is brass

A

A mixture of copper and zinc

28
Q

What is bronze

A

A mixture of copper and tin

29
Q

What is harder brass or bronze?

A

Bronze

30
Q

What is heat treatment?

A

The process of heating and cooling metal to change one or more of its properties.

31
Q

What is pearlite

A

The structure of soft steal

32
Q

What is martensite?

A

The structure of hardened steel.

It consists of angular needle like crystals

33
Q

What is Austenite?

A

Austenite is formed when pearlite is heated to red hot cause the layers of ferrite and cementite to begin to dissolve into each other. When Austenite cools it it changes into either pearlite or martensite.

34
Q

What is the basic process for heat treating steel?

A

Hardening - heated to form Austenite and rapidly cooled to form martensite. Only steel is .20% or more can be hardened.

Tempering - heating and cooling steel to take away the brittleness.

Annealing - use to make hardened material soft again so it can be machines

Normalizing - the process that eliminates strains and restores the proper grain structure of the steel

35
Q

What is the rockwell hardness test?

A

A tester that determines the hardness of a specimen by measuring how far you can force a penetrator into it.

36
Q

What metal do you use the penotrator with pointed diamond?

A

Hardened materials

37
Q

When do you use the steel ball penotrator?

A

Softer steels and non ferrous metals

38
Q

What is the Brinell hardness testing?

A

A hydraulic press is used to force a round penotrator into the material and the indent is measured

39
Q

What are some ways to identify metal?

A

Chip test
Spark test
File test
Flame test

40
Q

Smooth continuous chips indicate?

A

Soft material like aluminum copper or low carbon steel

41
Q

Small brittle chips indicate?

A

Higher carbon steels

42
Q

Low carbon steel produces what kind of sparks?

A

Bright, long, straight, yellowish

43
Q

High carbon steel sparks?

A

Burst near the wheel, darker Yellow

44
Q

Cast iron sparks?

A

Red burst near the grinder wheel and orange-yellow further out. May have to apply more pressure to produce sparks

45
Q

High speed steal sparks?

A

Lines are orange with very little branching and end up in ball shaped sparks

46
Q

What is an alloy?

A

A mixture of a metal with other metals or non metals

47
Q

Metal weight chart

A
48
Q

Cold rolled steel has a smooth grey surface and is produced by cleaning the scale from hot rolled billets then drawing them through rollers or dies until desired shape and size is reached. Why is cold rolled steel more expensive then hot rolled?

A

Cold rolling is a finishing process

49
Q

Why does cold rolled steel tend to warp when cut?

A

The process of cold rolling sets up internal stresses

50
Q

Carbon content of:
Low carbon steel
Medium carbon steel
High carbon steel
Cast iron

A

.02-.30% cannot be hardened most parts are made of low carbon steel

.30 - .60% better mechanical properties than low carbon steel and higher tensile strength. Can be hardened found in hand tools

Over .60% meant to be hardened and is found in cutting tools like taps and drills.

Cast iron is anything over 1.7% carbon

51
Q

Why must quenching be done immediately after it has been sufficiently heated when hardening?

A

If the steel is allowed to cool, it reverts to pearlite (soft steel) instead of martensite(hardened steel)

52
Q

What is most effective quenching?

A

Brine followed by:
Water
Oil
Air

53
Q

When do you want to temper the steel and why?

A

Temper must be done immediately after hardening or it will crack.

Tempering draws out the brittleness cause by the hardening process

54
Q

Tempering steel involves 3 steps

A

1: heating the steel carefully and observing color changes.
2: stop heating when area you are tempering reached the right temperature
3: quench

55
Q

When file testing steel what are some key points to remember?

A

1: if the metal can be filed, then it can be drilled, turned, or milled. If it cannot be filed the work piece must be ground

2: helps select the correct hardness scale thereby preventing damage to the penetrator.

3: can tell you if the work piece has been properly hardened. If the file bites in it means it was not hardened properly

56
Q

File action in Rockwell scale

A
57
Q

Hot rolled steel characteristics?

A

Scaled surface

Rounded edges

Slight irregularities

More ductile/malleable/ tough than cold rolled

58
Q

Cold roll steel characteristics

A

Cleaner surface finish
Square edges
Better dimensional accuracy
Harder and stronger than hot rolled