Chapter 1, Welding Processes Flashcards
(93 cards)
1
Q
The most arc efficient welding process is the ________ process
A
SAW
2
Q
The arc force control in CC welding power sources is used to ___________ in the SMAW process.
A
increase the penetration of the weld when the arc length is decreased
3
Q
The main controllable process variables for the resistance welding process are ______
A
electrode size, pressure, current and time
4
Q
The pinch force that aids in droplet detachment during spray transfer is produced by _________
A
a self-induced magnetic field
5
Q
The purpose of a brazing flux is to _______
A
remove oxides and reduce the surface tension of the molten filler
6
Q
The welding current in the GMAW process is determined by which of the following variables?
A
Wire feed speed
7
Q
Worm tracks produced using the FCAW process can be avoided by ______
A
decreasing current and voltage
8
Q
The submerged arc welding process incorporates _____________
A
a continuous fed solid wire and a constant voltage power source and the arc covered by flux
9
Q
The twin wire SAW process involves _______
A
one wire feeder with two wires and one DC power source
10
Q
In Friction stir welding, fatigue properties are outstanding compared with other welding methods. (True/False)
A
True
11
Q
MCAW uses a continuous filler metal electrode with a hollow core that is filled with ingredients to stabilize the arc: (Multiple Choice)
A
Flux, Iron Powder, Manganese and Silicon, Feroalloys, Stabilzers and other metals
12
Q
Modern inverter GTAW power sources use different methods for arc starting, except for: (Multiple Choice)
A
Steel Wool
13
Q
Gas tungsten arc welding with direct current electrode negative polarity is mostly used for: (Multiple Choice)
A
Carbon and Stainless Steels
14
Q
There are three variations of the friction welding process: (True/False)
A
True
15
Q
Name one advantage of brazing. (Multiple Choice)
A
Low Distortion and residual stress
16
Q
The biggest disadvantage of the electroslag welding process is: (Multiple Choice)
A
D) Large grained weld metal and heat-affected zone.
17
Q
With the flux cored arc welding process, which wire provides the best notch toughness? (Multiple Choice)
A
Basic Wire
18
Q
A wire designated by CSA Standard W48 as an E491T-9MJ-H8: (Multiple Choice)
A
A) Results in a weld deposit with a maximum of 8 ml of diffusible hydrogen per 100 g of weld metal.
19
Q
The plasma arc welding process involves: (Multiple Choice)
A
B) A non-consumable electrode with an orifice to constrict the arc.
20
Q
A substance with metallic properties and composed of two or more chemical elements of which at least one is a metal is known as: (Multiple Choice)
A
Alloy
21
Q
Fluxes that significantly influence the weld metal composition are termed: (Multiple Choice)
A
Active Fluxes
22
Q
SAW can utilize multiple electrodes fed into the same weld pool considerably increasing the deposition rate. Which one of the multiple wire arrangements listed below indicates that the current path is from one electrode to another through the weld pool? (Multiple Choice)°
A
Series Arc Welding
23
Q
Do fluxes used for soldering replace pre-cleaning? (Multiple Choice)
A
No
24
Q
When an arc is formed between two electrodes: (Multiple Choice)
A
A) Electricity flows from the negative cathode to the positive anode.
25
In the GTAW process, which current type/polarity will assist in the greatest removal of surface oxides? (Multiple Choice)
DCEP
26
Thermite welding is a process involving: (Multiple Choice)
A) An exothermic chemical reaction generating heat to melt the weld metal.
27
What is a major advantage of the EBW process? (Multiple Choice)
D) Welding thick sections in a single pass.
28
Explosion welding is typically used to: (Multiple Choice)
C) Clad metals onto carbon or stainless steel.
29
In diffusion welding, coalescence occurs through a two-stage metallurgical sequence. (True/False)
True
30
To produce a flat weld profile and good penetration profile using the MCAW process a: (Multiple Choice)
C) 15° travel angle using a push technique should be used.
31
What are two advantages of the LBW process? (Multiple Choice)
A) Easily automated and produces narrow welds.
32
The gas metal arc welding process uses: (Multiple Choice)
B) Both inert and active gas mixtures.
33
GMAW spray transfer is achieved with: (Multiple Choice)
D) High current, high voltage, and argon-rich shielding gas.
34
The strength of the magnetic field, and therefore the pinch effect, depends mostly on: (Multiple Choice)
Current Density
35
GMAW's higher productivity compared to SMAW is partially due to: (Multiple Choice)
A higher duty cycle
36
Small amounts of hydrogen can be added to shielding gas mixtures. Hydrogen containing gas mixtures can only be used to weld: (Multiple Choice)
A) Austenitic stainless steels.
37
Select the correct statement regarding resistance welding. (Multiple Choice)
A) The maximum amount of heat will be generated at the point of maximum resistance.
38
Resistance spot welding is most commonly employed for what type of joint? (Multiple Choice)
Lap
39
The melting rate of the SMAW electrode is dependent on: (Multiple Choice)
Current
40
The function of the ingredients in a SMAW electrode coating is to: (Multiple Choice)
A) Provide a gas shield, slag covering, scavengers, arc stabilization, and additional alloying elements.
41
A voltage sensing wire feed system must be used with a ___________ to produce a stable self-regulating welding arc.
CC power source
42
The conductor size of the secondary windings of a welding transformer power source is _______________________.
larger than the primary winding
43
Mechanical reactor control is used on which type of welding power source?
AC Transformer
44
A saturable reactor power source uses ________________ to adjust the output .
a third winding on the transformer
45
Which was the first type of welding power source to provide accurate control of the pulsed GMAW process over a wide range of pulse frequencies?
Transistor output
46
DC generator is different to alternator because:
DC generators have a conductor that moves quickly through a magnetic field
47
How much do the labour and overhead costs account for welding production? (Multiple Choice)
B) 80%.
48
Is the dirt inside a power source likely to create a short circuit? (Multiple Choice)
A) Yes.
49
When a sufficient amount of energy is imparted to the atom in a gas, this energy produces: (Multiple Choice)
C) Free electrons and positively charged ions.
50
A plasma can best be described as: (Multiple Choice)
A) An ionized gas.
51
What is the minimum temperature in the centre of a welding arc column? (Multiple Choice)
C) 5,000 °C.
52
What does IGBT stand for in welding? (Multiple Choice)
A) Insulated-gate bipolar transistor.
53
To create or support an ionizing path in arc starting circuits for a high frequency setting, the ratio of volts to amps is: (Multiple Choice)
C) 20,000 volts with 0.005 amps.
54
The severity of an electric shock depends principally on: (Multiple Choice)
B) Magnitude of the current and part of the body through which it passes.
55
Inverter based power sources are usually heavy and bulky. (True/False)
False
56
Power sources that use pulse technology suffer from inductance in the welding circuit affecting precision and sharp pulses of current. What measures should be taken to obtain the best result? (Multiple Choice)
C) Keep output cables as short as is sensible.
57
The main components used to rectify are: (Multiple Choice)
A) Diodes.
58
It is essentially impossible to maintain a stable welding arc with the SMAW process and a constant voltage power source. (True/False)
True
59
What is the purpose of an inverter? (Multiple Choice)
B) To convert DC current to high frequency AC current.
60
The two systems that can be used to adjust the output of a transistor welding power source are: (Multiple Choice)
C) Frequency and pulse width modulation.
61
The capacity to store and recall detailed welding variables in a welding power source is possible due to: (Multiple Choice)
D) Microprocessor controls.
62
A problem with reactively controlled welding machines is the low power factor. What is the ideal power factor? (Multiple Choice)
A) 1 power factor.
63
Select the correct statement. (Multiple Choice)
A) A CC welding power source can be used for the GTAW and PAW processes.
B) A CC welding power source can be used for the SMAW process.
C) A CV welding power source can be used for the GMAW and FCAW processes.
(D) All of the above.)
64
In some situations with the SMAW process, such as manual welding of pipe joints, a flatter slope is used to provide some change in current when arc length changes. (True/False)
True
65
Wire feed systems that employ constant current control the arc by: (Multiple Choice)
C) Voltage sensing.
66
With real constant voltage sources, the voltage drops as current draw increases. For welding sources this is usually no more than:
B) One volt or so for 100 amperes of output current draw.
67
How is the dynamic characteristic of a power source controlled?
C) By resistance and inductance.
68
The self regulating arc created by a constant voltage power supply is most commonly associated with a constant speed wire feeder. With this type of equipment: (Multiple Choice)
B) When arc length increases, welding current decreases.
69
What are the three main components when charging a blast furnace? (Multiple Choice)
C) Iron ore, limestone, and coke.
70
What is required to form iron in a blast furnace? (Multiple Choice)
B) A reducing agent, carbon monoxide.
71
During the smelting of iron, "reduction" refers to removing: (Multiple Choice)
B) Oxygen from the ore.
72
How can low sulphur steels be produced if desired to give improved through-thickness properties? (Multiple Choice)
A) By using additives such as calcium.
73
There are several steel types, one is the TMCP type steels. What are these? (Multiple Choice)
A) TMCP involves controlled hot working and a microalloyed steel composition.
74
A method of strengthening is solid solution hardening, what does this entail? (Multiple Choice)
Question 6 options:
A) Adding an alloy atom that is small enough to replace the host metals atoms.
B) Adding an alloy atom that is large to distort interstitial sites between the host metals atoms.
C) Substitute a BCC lattice with the FCC lattice as it is smaller and will therefore produce smaller grains
D) Increasing the amount of small inclusions into the solution during the compositional stage during melting.
A) Adding an alloy atom that is small enough to replace the host metal's atoms.
75
The higher strength of Thermo-Mechanically Controlled Processed steels (TMCP) is due to: (Multiple Choice)
Question 7 options:
A) Small grains and the formation of acicular ferrite grains.
B) Large elongated grains.
C) Round small grains.
D) Square grains.
A) Small grains and the formation of acicular ferrite grains.
76
In the precipitation hardening alloys, change in hardness during aging can be influenced by: (Multiple Choice)
Question 8 options:
A) Temperature and quenching time.
B) Temperature and time.
C) No change at all.
D) Only temperature.
B) Temperature and time.
77
What is the best way to explain precipitation hardening? (Multiple Choice)
Question 9 options:
A) The precipitation of small particles in the host metal impeding dislocation.
B) The precipitation of large particles impeding dislocation.
C) Precipitation of particles to the matrix facilitating dislocation.
D) None of the above.
A) The precipitation of small particles in the host metal impeding dislocation.
78
The ductility measured through the thickness of the plate is usually the lowest of all. The welding of large heavily restraint tee joints may therefore result in: (Multiple Choice)
Question 10 options:
A) Ductile tearing.
B) Lamellar tearing.
C) Hydrogen tearing.
D) Brittle tearing.
B) Lamellar tearing.
79
There are several metallurgical phases in a steel depending on its carbon content and heating history. How is ferrite best described? (Multiple Choice)
Question 11 options:
A) A complex phase that occurs above 723 °C.
B) A phase that depends on fulfilling its structure by fast cooling.
C) A solid solution in a face-centered cubic (FCC) phase of iron that dissolves only small amounts of carbon.
D) A solid solution in a body-centred cubic (BCC) phase of iron that dissolves very small amounts of carbon.
D) A solid solution in a body-centred cubic (BCC) phase of iron that dissolves very small amounts of carbon.
80
What is the difference between Eutectic point and Eutectoid point? (Multiple Choice)
Question 12 options:
A) In the Eutectic, the liquid in the phase diagram forms two solids, and the Eutectoid a single solid in the phase diagram forms two solids.
B) Eutectic means solid.
C) Eutectoid means liquid.
D) In the Eutectic, the solid in the phase diagram forms two solids and the Eutectoid is the opposite of the Eutectic.
A) In the Eutectic, the liquid in the phase diagram forms two solids, and the Eutectoid a single solid in the phase diagram forms two solids.
81
Chromium is a useful non-ferrous metal for alloying and it has significant advantages because of certain properties. Which of the following would be a significant property for this material? (Multiple Choice)
Question 13 options:
A) Its light and used in aircraft alloys.
B) It increases corrosion resistance and hardness.
C) It softens a steel when alloyed with it.
D) It increases the electrical conductivity when added to steel in micro amounts.
B) It increases corrosion resistance and hardness.
82
Fast cooling rates through the transformation temperature range (800-500 °C) in steel: (Multiple Choice)
Question 14 options:
A) Suppress the transformation temperature.
B) Promote a coarser pearlitic structure.
C) Develop a mixed arrangement of ferrite and pearlite grains.
D) Dissolves the original martensitic grains.
A) Suppress the transformation temperature.
83
Iron can change its crystallographic form as temperature changes. What form does iron take at a temperature of 250 degrees Celcius? (Multiple Choice)
Question 15 options:
A) The body-centered cubic ferrite lattice form.
B) The face-centered cubic austenite lattice form.
C) The close-packed hexagonal delta lattice form.
D) The distorted lattice form known as pearlite.
A) The body-centered cubic ferrite lattice form.
84
Which one is harder, coarse pearlite or fine pearlite? (Multiple Choice)
Question 16 options:
A) Both the same.
B) Fine pearlite.
C) Coarse pearlite.
D) Fine pearlite is always softer.
B) Fine pearlite.
85
Metals have a crystalline structure in which atoms are arranged in irregular patterns. (True/False)
Question 17 options:
True
False
Correct answer: False
86
Hot shortness is: (Multiple Choice)
Question 18 options:
A) Volume change created by transformation.
B) Cracking susceptibility caused by high sulphur content.
C) The uncontrolled transformation of pearlite to austenite.
D) Cracking susceptibility caused by excessive hardness
B) Cracking susceptibility caused by high sulphur content.
87
The carbon content of a specific steel grade, e.g. 4340: (Multiple Choice)
Question 19 options:
A) Depends only on the nickel content.
B) Depends only on the type of furnace in which the steel is made.
C) Will not be uniform, but will fall in a specified range.
D) Can be whatever the client requires.
C) Will not be uniform, but will fall in a specified range.
88
What is a prime requirement when purchasing steel? (Multiple Choice)
Question 20 options:
A) No requirement.
B) The thickness.
C) The physical properties.
D) The steel specifications.
D) The steel specifications.
89
Thicker plates of the same steel designation will be designed with higher: (Multiple Choice)
Question 21 options:
A) Carbon content than thinner plates.
B) Sulphur content than thinner plates.
C) Hardness content than thinner plates.
D) Phosphorous content than thinner plates.
A) Carbon content than thinner plates.
90
When the carbon content increases in steel: (Multiple Choice)
Question 22 options:
A) Ductility increases and strength decreases.
B) Ductility and strength decrease.
C) Strength increases and ductility decreases.
D) No change in mechanical properties.
C) Strength increases and ductility decreases.
91
When designing a steel to improve its hardenability and thus its strength, what is the normal approach? (Multiple Choice)
Question 23 options:
A) Increase the grain size of the steel.
B) Use a heat treatment that is guided by the mill followed by a stress relief.
C) Use a small amount of several hardening elements as the effect is better than using a single element.
D) Use a single element such as carbon which has great hardenability and improves the weldability of the steel.
C) Use a small amount of several hardening elements as the effect is better than using a single element.
92
High carbon steels typically provide: (Multiple Choice)
Question 24 options:
A) High toughness.
B) High strength.
C) Good welding properties.
D) Good corrosion protection.
B) High strength.
93
There is a major group of low alloy steels that are intended for various structural applications and have higher yield strengths than regular carbon steels. What are these steels generally known as? (Multiple Choice)
Question 25 options:
A) Super strength low alloy steels or SSLA steels.
B) High strength medium alloy steels or MSLA steels.
C) High strength heat treatable steels or HSHT steels.
D) High strength low alloy steels, or HSLA steels.
D) High strength low alloy steels, or HSLA steels.
