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Welder exam Flashcards

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Welding Inspection Basics flashcards
1
Q

Carbon equivalent

Equation?

A

CE = C + Mn /6 + (Cr + Mo + V) / 5 + (Ni +Cu) /15

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2
Q 
Heat input equation (Q)?
What does the following stand for 
Q 
E 
I
V
A 
Q = welding energy input 
E = voltage 
I = welding current amperage 
V = welding speed

EI / V x 60/1000

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3
Q

What is ferrite stainless steel?

A
  • Austenitic
  • Martensitic
  • Duplex
    ( High chromium low carbon, magnetic ).
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4
Q

Ferrous metals

A

Mild steel, carbon steel, stainless, cast, wrought iron

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5
Q

Nonferrous metals

A

Aluminium, aluminium alloys, copper, brass gold, silver, tin, lead, zinc

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6
Q

Carbon phase diagram

A

Check answer use PowerPoint

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7
Q

Temperatures Grain structure etc

carbon equivalent..

A 
Refer to exam
and assignments ( perlite cementite etc)
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8
Q

What is a welding supervisors roll (AS 1796 / AS 2214)?

A

A welding supervisor is expected to control essential welding related aspects for any project, responsible for vessels, or structural production, over looking technical aspects (material welding procedures etc), safety and liaising with other parties included within the production.

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9
Q

Explain Duty cycle ?

A

The ratio of time during which the operator is actually welding to the total time he is on the job. Eg 30% duty cycle - welding at 150 for 3 minutes the welder will require 7 minutes rest.

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10
Q

Explains Deposition rate ?

A

The mass of metal deposited per minute, determined by the current used.

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11
Q

List two advantages and two disadvantages for a single vee and a double U joint

A

Already know

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12
Q

Name two main initiation mechanisms for gtaw.

A

HF and scratch start.

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13
Q

Describe electrode classification number E5518 from the AS / NZS 4855:2007 standard

A

Look up

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14
Q

Explain the term deposition efficiency in the relation to welding consumables ?

A

Look up

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15
Q

Explain brittle fracture?

A

This usually occurs with high strength or hardened steels. It is a quick fracture as the material have no room for ductility.

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16
Q

Explain fatigue ?

A

Fatigue is the form of structural failure caused by the action of fluctuation stresses.
This is also cause by containing weld defects -
* abrupt weld toes
* excessive reinforcement
* under cut
* lack of fusion, inclusions etc

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17
Q

Explain Stress corrosion ?

A

When cracking occurs through or across the grain boundaries.

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18
Q

Explain lamellar tearing ?

A

Not a weld defect. But is exposed from welding or fabrication. The defect appears below the weld on the HAZ boundaries. Lamellar tearing is a micro defect which is usually caused during the manufacture of plate.

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19
Q

Explain creep ?

A

When materials are subjected to high temperatures and load, the metal will tend to creep over time (deform), until it can not be used or even rupture.

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20
Q

Explain inter granular corrosion ?

A

This occurs in stainless steel and high nickel alloys. This is caused from rapid heating and forms around the HAZ area. Carbon migrates to the grain boundaries.

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22
Q

List and explain 7 types of destructive testing.

A
  • Bend test - bending material in die to chec
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23
Q

What are some alloying elements ?

A
  • manganese
  • chromium
  • nickel
  • molybdenum
  • copper
  • silicon
  • vanadium
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24
Q

What does manganese do when added to steel ?

A
  • Hardens steel when combine with carbon

* Helps produce fine grain structure

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25
Q

What does nickel do when added to steel ?

A
  • Produces strength toughness resistance to abrasion.
  • The steels do not suffer grain growth.
  • Lowers the critical temperature.
  • Minimizes distortion when quenched.
  • Produces hardening properties.
  • Can be magnetized.
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26
Q

What does chromium do when added to steel ?

A
  • Raises the critical temperature of the steel.
  • Above 11% becomes corrosion resistance.
  • Creates stability
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27
Q

What does Molybdenum do when added to steel ?

A
  • Increases tensile strength and toughness.
  • Becomes brittle with heating.
  • High resistance to creep.
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28
Q

What does silicon do when added to steel ?

A
  • Helps with corrosion resistance.
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29
Q

What does copper do when added to steel ?

A
  • About 1% is used in structural steels to promote hardness, fine grain, added strength and toughness.
  • Adds magnetism.
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30
Q

What does Vanadium do when added to steel ?

A
  • Increases tensile strength.
  • Increases elastic limit.
  • Increases resistance to fatigue.
  • Used for high stressed.
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31
Q

State 5 functions of the flux cored arc welding process?

A
  • Stabilize Arc.
  • Shield molten metal from atmosphere.
  • Scavenges Impurities.
  • Controls shape of weld.
  • Adjust chemical composition of the weld.
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32
Q

Name four metal transfer types in gas metal arc welding.

A
  • Globular
  • Spray arc
  • Short circuiting transfer
  • Pulse transfer.
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33
Q

List three reasons why SAW solid wires are copper coated?

A
  • It improves the current pick up between contact tip and the electrode
  • It aids the drawing process
  • It helps prevent rusting of the wire
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34
Q

Explain open circuit voltage of welding power source

A

A welding machine that is turned on but not being used.

35
Q

Explain Deposition Efficiency (for continuous electrodes)

A

Deposition efficiency in arc welding is the ratio of the weight of the weld metal deposited to nett weight of the filler material used.

36
Q

Explain the difference between soldering and welding.

A
  • Soldering doesn’t exceed 450 degrees

* Welding melts but the filler and the base metal

37
Q

What are Voltage Reducing Devices (VRDs)? List the three types of VRDs commonly used in the industry.

A

Reduces the chance of getting an electric shock
The three types of VRDs are:
Type 1: Externally fitted to secondary circuit
Type 2: Internally fitted to secondary circuit
Type 3: Fitted to primary circuit

38
Q

What is magnetic arc blow? State three methods of reducing it.

A

Magnetic arc is when the arc wonders in the DC current mode

  1. Change from DC to AC
  2. Reduce welding current
  3. Change the angle of the electrode
39
Q

A steel, with the chemical composition as shown below, and of known heat analysis, is tobe used in structural fabrication.

A

Refer to question 11 to find preheat etc.

40
Q

What is a phase diagram (also called equilibrum diagram or constitution diagram)? Give two uses of the iron-carbon equilibrium diagram.

A

It is a two-dimensional graph which indicates the phases present at a given temperature and composition.
To get some idea of the conditions of temperature and pressure that are likely to produce a gas , a liquid , or a solid.
To find the combinations of temperature and pressure at which two states are in equilibrium.

41
Q

Question 13

With the aid of a diagram , describe the phenomenon of creep, State three elements that contribute to creep damage.

A 
When materials are subjected to high temperatures and load, the metal will tend to creep over time (deform), until it can not be used or even rupture.
The three elements
1. Elongation 
2. Time 
3. Rupture
42
Q

Give two reasons why preheat is used when welding a high carbon equivalent steel? List two methods of applying preheat

A
  • To slow cooling rate of the material.
  • To reduce hydrogen in the weld zone - preventing cracking.
    *
43
Q

who loves you…..

A

chlo xx keep up the good work xx

44
Q

Explain ambient temperature?

A

Is the air or base temperature of the steel.

45
Q

List the three stages in the development of welding procedures.

A

The proposed welding procedure
The procedure qualification record-PQR
The welding procedure specification- WPS

46
Q

List five common essential variables for the MMA W process with reference to
AS/NZS 1554 Part 1.

A
  • A change in specified mean arc voltage
  • A change in specified mean welding current
  • A change in position in which the welding is done or change in welding direction
  • A change from single pass to multipass
  • A change in minimum specified preheat or inter-run temperature
47
Q

List the five methods of qualifying welding procedures available in AS/NZS 1554

A
  • A pre-qualified procedure
  • Production of documentary evidence of relevant prior experience by the fabricator
  • Production of a suitable length of test piece of the same joint type, material type, material thickness and edge preparation, material type and direction of rolling
  • Preparation of a special test piece
  • Destructive testing of a prototype joint
  • A welding procedure qualified by another fabricator
48
Q

List three reasons for having an “

Inspection and Test Plan (ITP)”.

A
  • Detailing systematic approach. ( materials Machine etc.
  • Smooth production and quality control.
  • Customer involvement with the production.
  • State whom done the NDT inspection.
49
Q

List ten components or elements of a typical ITP.

A
  • Material receipt
  • Source.
  • Welder Qualification.
  • Pressure testing.
  • Documentation.
  • Material testing.
  • Material cutting.
  • Welding procedures.
  • Welding.
  • Painting.
50
Q

What is the intended action for the manufacturer’s inspector when the following test points are specified in the ITP? H and W

A
  • Hold - until verification of testing.

* Witness - Fabrication is not to proceed until manufacture’s inspector has verified.

51
Q

Give two possible causes for each of the welding imperfections and one method of preventing each cause.
Excessive weld metal, Undercut

A

Excessive weld metal
Excessive weld metal which is usually a result of poor welder technique for manual processes but may be due to poor parameter selection when the process is mechanised. That is, too much filler metal for the travel speed used.
If the imperfection is a result of welder technique then welder retraining is required. For mechanised techniques an increase in travel speed or voltage will help to reduce cap height.
Undercut
A wide spreading arc (high arc voltage) with insufficient fill (low current or high travel speed) is the usual cause. However, welder technique, especially when weaving, and the way the welding torch is angled can both cause and be used to overcome undercutting ( ie angled to push the weld metal to fill the melted groove). High welding current will also cause undercut - this is generally associated with the need for a high travel speed to avoid overfilling of the joint.
This imperfection may be avoided by reducing travel speed and/or the welding current and by maintaining the correct arc length.

52
Q

State two limitations of the ultrasonic inspection method

A
  • Permanent record is difficult to obtain

* Requires high level of skill in interpreting indications

53
Q

Name these Standards

AS2865 ,AS1966 ,AS1674

A

AS2865 Safe working in confined space
AS1966 Electric arc welding machines
AS1674 Safety in welding and allied processes-fire precaution

54
Q

What is Stainless steel?

A

Stainless is formed when you have more than 10% chromium, which gives stainless steel its corrosion resists. 12 % with out any other alloying additions.

55
Q

List and explain four basic groups of stainless steel.

Power point explains the different grades of these s/s.

A
  • Austenitic -
  • These steels are all alloys of iron, chromium and nickel.
  • Non- Magnetic in the annealed condition.
  • Strengthened by Cold working. Higher nickel
    contents.
  • These alloys are easy to weld .
  • Generally require no pre-heat or post heat.
    Austenitic Stainless is the most common
    stainless steel ,accounting for 70% of
    consumption in Australia.
  • Ferritic
  • These steels are alloys of iron and chromium.
  • They are Magnetic.
  • They may be readily welded by resistance
    spot or GTAW in thin sheet form.
  • Not suitable for thick welds requiring large
    heat inputs , or multiple pass welding , due to
    their susceptibility to grain growth.
  • Martensitic
  • Alloys of iron and chromium.
  • Can be hardened by heat treatment.
  • They are magnetic.
  • Difficult to weld , due to their susceptibility to
    hardening in the weld zone .
  • Pre – and Post – weld heating heating is
    required.
  • The major use of Martensitic stainless steels
    is in corrosion and heat resistant castings
    where their high strength gives them an
    advantage over the more expensive
    Austenitic alloys
  • Duplex grades
56
Q

Explain normalizing , annealing ,post weld stress relieving

A

Normalizing – Mechanical properties of steel can be improved by normalizing, Material is normalised to overcome the variations of grain size in weld size.
The steps to normalizing are:
Heat the steel to about 60’c above the higher crital temperature
Hold to allow for even heating
Cool to room temperature in still air
Temperature range 820’c to 925’c

Annealing: Annealing is a heat treatment which softens the material so it can be bent, formed and machined.
The steps of annealing are:
Heat the material to above the critical temperature range.
Hold to allow for even heating
Furnace cool at a controlled slow rate
Temperature range: 820’c to 925’c

Post weld stress relieving:Stress relieving removes locked stress( residual stress) caused by cold working and shrinkage stress caused by welding.
The steps of stress relieving are:
Heat the work slowly.
Hold the work at the recommended heat treatment temperature for specified time.
Cool the work slowly
Temperature range: 590’c to 670’c

57
Q

Explain the term sensitisation as applied to stainless steel . List methods of preventing it.

A

This is know also know as chromium carbide precipitation and this condition primarly effects the heat effect zone , depend upon the level of carbon and the length of time the material stays in the critical temperature range 450’c to 850’c

Prevention : Use low carbon grades stainless steel
The weld should be allowed to cool down to less than 100’c before the next run.
Heat input should be kept should be kept down by using low volts and amps and stringers

58
Q

Why is PWHT required?

A
  • Reduce residual stresses, improves resistance to brittle fracture, stress, corrosion, eliminates distortion.
  • Restores materials properties.
59
Q

What stage is PWHT carried out?

A

Prior to hydrostatic testing.

60
Q

Why is PWHT carried out in a furnace?

A

Because it does not exceed 400 degrees.

61
Q

Explain PQR ? (procedure qualification record)

A

Document providing the actual welding variables used to produce an acceptable weld test.

62
Q

Explain WPQ ?

A

The welding Procedure Qualification (WPQ)
is a detailed record of all contributing
occurrences at the time of welding the
nominated procedure test plate. This detail
includes actual welding parameters, with no
adjustment for variances ( essential
variables) that may be permitted by code or
specification . i.e the WPQ is a record of
what actually took place . Hand written

63
Q

Explain WPS ? (welding procedure specification)

A

Document that references all welding variables required by the code that the welding is being carried out to.

64
Q

Explain welding variables ?

A

Welding data that is recorded on the WPS and the PQR

65
Q

Whats the purpose of a welding procedure?

A
  • welds are fit for their intended purpose
  • customers are satisfied
  • uniformity and repetition of work practices
  • a permanent record of welding parameters is kept
  • welds on pressure vessels meet the requirements
    of a statutory body, code.
66
Q

Steps for providing a weld procedure?

A
  1. Prepare and weld a suitable test sample
  2. Test the weld sample by non-destructive and
    destructive testing
  3. Evaluate weld performance
  4. Consider possible changes to the initial
    welding procedure.
  5. Get approval for the statutory authority.
  6. Record the accepted procedure.
67
Q

Welding procedure steps prior to production?

A
  • Write up a welding procedure
    specification
  • Qualify this procedure by test
  • Qualify the welders by test
  • Record full details of the procedures
    and all qualification data
68
Q

(Note) Use Slide Welders certification AS 1796-2001

A

For filling out a weld procedure guidance

69
Q

(Note) Also use assignment 4 unit 4

A

as a weld procedure guide..

70
Q

Estimating Cost.

A

Refer to power point / assignments.

71
Q

Welding processes.

A

Refer to exam. tig electro slag welding etc

72
Q

Shielding gasses

A

Shielding purging etc

73
Q

Explain Ferrite.

A

Steel contain a lot of ferrite will there for be soft, with low tensile strength, but will be tough and durable. contains very little carbon.

74
Q

Explain Pearlite.

A

A laminated structure of ferrite and cementite. The hardness increases, as the carbon content rises up to 0.85%.

75
Q

Explain Cementite

A

Extremely hard and brittle. Used for ball bearings, tools etc. these, materials need to be heat treated very carefully.

76
Q

Explain Austenite.

A

This is the structure of iron at high temperatures (over 912 deg C).
Has a face-centre cubic (FCC) crystal structure. This material is important in that it is the structure from which other structures are formed when the material cools from elevated temperatures. Often known as γ iron. Not present at room temperatures.

77
Q

Explain Martensite.

A

A very hard needle-like structure of iron and carbon.
Only formed by very rapid cooling from the austenitic structure (i.e. above upper critical temperature). Needs to be modified by tempering before acceptable properties reached.

78
Q

Welding positions.

A

PA, PC, PFPG, PE

PB

79
Q

What is meant by the Carbon Equivalent and how is it used?

A

Equivalent carbon content (C.E) is used to understand how the different alloying elements affect hardness of the steel being welded. Used on Ferrous materials - steel and iron.

80
Q

List four effects on steel when carbon is increased.

A
  • Increases hardness.
  • Increases strength.
  • Increases brittleness.
  • Reduce weldability.
  • Reduce ductility.
81
Q

Assignment 4 unit 4

A

Is a good info source for weld procedures etc

Welding exam (3 decks)

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