102 Flashcards

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1
Q

What are the breakers set to on a resident 220V circuit?

A

40-50 amps

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2
Q

Who is allowed to install electrical systems for welding machines?

A

A certified electrician

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3
Q

Define arc?

A

An arc is created when there is enough amperage and voltage available at the electrode tip to overcome the natural resistance

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4
Q

What is the metal deposition rate?

A

It’s another term for burn off rate

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5
Q

What controls the core in a coil?

A

A moveable shunt

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6
Q

What body rates welding machine duty cycles?

A

National electrical manufacturers association (NEMA)

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7
Q

What is a electron?

A

Negatively charged particles that move through a conductor when current flowing

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8
Q

If a generator produces AC current what may it also be called?

A

An Alternator

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9
Q

What’s an inverter?

A

An inverter is a device that changes DC to AC

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10
Q

What is a rectifier?

A

A rectifier is a device that changes AC to DC

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11
Q

If you lengthen your stickout during a gmaw welding process what are you changing in the circuit?

A

You are adding resistance to the circuit which may lead to stubbing

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12
Q

When using straight polarity where is the majority of the heat?

A

2/3 of the heat will be in the electrode causing the electrode to melt

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13
Q

When using a CV machine how many rheostats will be on it?

A

2, one to set voltage and one to set wire speed

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14
Q

When looking at a volt-amp curve, if your line goes from volts and droops to amperage what kind of machine are you using?

A

Constant current

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15
Q

What two ferrous metals can’t be cut with a oxy-fuel torch?

A

Stainless steel and cast iron

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16
Q

What non ferrous metals can be identified by a spark test?

A

Nickel and titanium

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17
Q

What is the difference between red brass and yellow brass?

A

Red brass is more copper and less zinc, yellow brass on average 60% copper and 40% zinc

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18
Q

What are the two types of file hardness tests?

A

Rockwell and Brinell

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19
Q

This hardness test uses conical diamond penetrator applied to a specific load. The amount that the penetrator indents tells the hardness what test is this?

A

Rockwell

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20
Q

When flame testing metal what are you looking for?

A

The speed of melting, changes in colour, the appearance and action of slag, the appearance of the molten puddle, action if the molten puddle under the flame

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21
Q

If the heat identification number is removed from a plate what must be done?

A

Transfer it to the remaining plate

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22
Q

When metal is shipped what comes attached to the metal?

A

Mill report and metal specification tag

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23
Q

Define compressive strength

A

The resistance of material to a force that tends to deform or fail it by crushing

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24
Q

Define shear strength

A

The maximum load that a metal can take before it fractures across its section

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25
Q

Define tensile strength

A

The ultimate pull that a material will stand without fracture

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26
Q

Define yield strength

A

The stress point at which permanent deformation takes place

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27
Q

Define impact strength

A

The ability of a metal to withstand a sharp high velocity blow

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28
Q

What is the elastic limit?

A

The maximum stress the metal will endure before permanent deformation takes place

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29
Q

Define ductility

A

The ability of a material to stretch or deform under load without breaking or failing

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30
Q

Define brittleness

A

The tendency of a material to fail suddenly by breaking without any permanent deformation before failure

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31
Q

Define hardness

A

A materials ability to resist penetration or indentation

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32
Q

Define toughness

A

The ability of metal to withstand a rapidly applied load without breaking

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33
Q

Define elasticity

A

Is the ability of a metal to return to it original shape and dimensions once a load is removed

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34
Q

Define Malleability

A

A metals ability to be cold worked without a great deal of resistance

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35
Q

What test is used to determine impact strength?

A

Notch test

36
Q

What term describes the rate heat travels through metal?

A

Thermal conductivity

37
Q

Ferrous metal has a high content of ________?

A

Iron

38
Q

What phase of power supplies are used in most industrial applications?

A

Three phase power

39
Q

When talking about electricity what does EMF stand for?

A

Electromotive force

40
Q

What charge do electrons hold?

A

Negative

41
Q

What is the purpose of a silicon controlled rectifier?

A

To change AC to DC

42
Q

What is the melting point of mild steel?

A

1510^C (2750^F)

43
Q

What is the heat affected zone?

A

The area on both sides of the weld directly adjacent to where the weld metal mixes with the parent metal

44
Q

What is resulting grain structure from a multi pass weld?

A

A finer grain structure, a general rule is a finer grain structure makes a stronger weld

45
Q

A finer grain structure provides greater ______ strength and _______ strength

A

Tensile and yield

46
Q

What four areas does the HAZ consist of?

A

Solid/liquid transition zone, grain growth zone, recrystalized zone, partially transformed zone

47
Q

Define temperature

A

Measures the Degree or intensity of heat, measured in Celsius (C) or Fahrenheit (F)

48
Q

Define heat

A

Expresses volume or quantity of heat, it is measured in British thermal units (BTUs) or in joules (J)

49
Q

When does solid expansion occur?

A

When metal is in a solid condition and has not reached its transition temperature

50
Q

What is the primary purpose of preheating?

A

To prevent high stress and cracking

51
Q

What is the temperature range for pre heating on average?

A

40^C-250^C (100^F-400^F)

52
Q

What is the primary purpose of post heating?

A

To slow the cooling rate of the weld and HAZ

53
Q

How does post heat affect hydrogen in the weld?

A

It allows hydrogen to migrate out of the weld, these hydrogen induced cracks can show weeks after welding stops

54
Q

What is the grain structure in martensite like?

A

Needle-like and the metal becomes very hard and brittle

55
Q

What causes martensite to form?

A

When steel is quenched the carbon does not have time to come out of solution which causes it to become trapped in crystalline structures which normal hold very little or no carbon which causes stress within the metal

56
Q

What determines post heat temperature?

A

Material thickness, carbon and other alloy content, whether the material was subjected to heat treatment when it was manufactured

57
Q

What is the purpose and process of normalizing?

A

Normalizing consists of heating an object above its upper critical limit for 1 hour for every inch of thickness this produces grain uniformity in the grain structure

58
Q

What is annealing?

A

The process of softening a material bringing it to its softest toughest, weakest state. This lowers tensile strength and raises softness and toughness

59
Q

What temperature range does the stress relieving process use?

A

600^C (1100^F)- 700^C (1300^F)

60
Q

How does tempering affect metal?

A

Reduces toughness and promotes toughness, it also reduces fragile brittleness and reduces internal stress

61
Q

What is hard facing?

A

Application of a hard, wear resistant metal or metal alloy to a surface of a softer metal by a welding process

62
Q

What is the purpose of hard facing?

A

Combat wear, prolong the life of an object, reduce costly down time, and reduce the cost of replacement parts

63
Q

When talking about hard surfacing what does ABR stand for?

A

ABR stands for Abrasive Resistance material

64
Q

When hard surfacing a loader bucket why do you put different patterns in the weld?

A

To make sure the wear happens only on the dirt and the hard surface material

65
Q

When hardfacing what polarity do you use?

A

Reverse polarity (DCEN)

66
Q

Define abrasion

A

Sliding/scraping type of wear that removes metal by gouging or grinding

67
Q

Define impact wear

A

Pounding or battering type of wear that splits, breaks, chips, mushrooms or otherwise deforms the metal surface

68
Q

Define erosion

A

Gouging type of wear that washes away or grooves out the metal surface

69
Q

What is galling?

A

Metal to metal wear

70
Q

Define corrosion

A

Wear that pits, perforated and eventually dissolves metal parts

71
Q

Define oxidation

A

Special form of corrosion that takes place when some metal are exposed to a combination of heat and air

72
Q

Define compression

A

Squeezing type of wear usually cause by heavy static load or loads that gradually increase pressure on metal surface

73
Q

Define thermal shock

A

Cracking or splitting wear caused by exposing metal parts to temperature extremes such as rapid heating and cooling cycles

74
Q

What is a common use of austenitic manganese? And why?

A

Railroad tracks, because it has very good work hardening characteristics

75
Q

What is dilution, what is a common cause of this?

A

The mixing of the base metal with the hardfacing material, using the wrong polarity is a very common cause of dilution

76
Q

What is spalling?

A

Spalling occurs when the weld metal breaks away from the base metal

77
Q

What are some ways to help prevent spalling?

A

Prepare the surface, control the cooling rate, limit deposit thickness

78
Q

Describe a hidden line, what’s its purpose?

A

Broken line of medium thickness, it shows edges and outlines not visible to the eye

79
Q

Describe a long break line, what is its purpose?

A

Ruled light lines with free hand zigzags, these lines are used to conserve space or to show a partial end of a section

80
Q

What is an architectural drawing?

A

A line drawing that shows plan and/or elevation views of the proposed building showing its OVERALL APPERANCE

81
Q

What does a mechanical drawing show?

A

It shows all the required mechanical components of the building

82
Q

What do section lines represent?

A

Different types of material when there is an imaginary cut surface

83
Q

What does leader line do?

A

A leader line I used to add a note or a dimensions

84
Q

Name the four weld types?

A

Surfacing, plug or slot, fillet, groove

85
Q

Name the five basic joints

A

Butt joint, corner joint, tee joint, edge joint, lap joint

86
Q

Which joints use fillet welds

A

Lap joint, tee joint, and corner joints