120102g Flashcards
Temperature expressed in degrees Fahrenheit or degrees Celsius refers to the measure of the
A) intensity of energy
B) amount of energy
C) volume of energy
D) quantity of energy
A) intensity of energy
The term heat expresses
A) quantity
B) degrees
C) temperature
D) intensity
A) quantity
Which is a common cause of distortion
A) using specified welding procedures
B) unequal heating and cooling of welds
C) free expansion and contraction
D) equal heating and cooling of welds
B) unequal heating and cooling of welds
When he did evenly and without restraint in which direction does metal expand
A) transversely ( across)
B) Longitudinally ( lengthwise)
C) volumetrically ( in all directions)
D) only upwards and downwards
C) volumetrically ( in all directions)
Transitional expansion occurs when a metal changes from
A) a solid state to a liquid state
B) one crystalline structure to another
C) one colour to another
D) a liquid state to a solid state
B) one crystalline structure to another
Which type of distortion results from shrinkage across the weld that tends to pull a member of Tee joint toward the welded side
A) transitional distortion
B) transverse distortion
C) longitudinal distortion
D) angular distortion
D) angular distortion
Which type of distortion results in an overall reduction in length of the weld
A) transitional distortion
B) transverse distortion
C) longitudinal distortion
D) angular distortion
C) longitudinal distortion
Which type of distortion refers to the tend( in butt joints ) for the plates to draw together down the length of the joint as you are welding
A) transitional distortion
B) transverse distortion
C) longitudinal distortion
D) angular distortion
B) transverse distortion
What causes angular distortion in a Vee groove weld if the plates are free to move?
A) the non-uniform contraction of the weld metal
B) the rapid cooling of the weld metal
C) making tacks too small on the end of the plate
D) the metal expanding when it cools
A) the non-uniform contraction of the weld metal
What is the primary cause of distortion created from longitudinal shrinkage
A) welding at a slow rate of speed
B) making tacks too small at the ends
C) a weld made using the wrong polarity
D) weld beads contracting upon cooling
D) weld beads contracting upon cooling
What welding variable is more likely to have the plates of a butt joint draw together, causing transverse distortion
A) welding at a faster rate
B) using straight polarity
C) using reverse polarity
D) welding at a slower rate
D) welding at a slower rate
What is one method you can use to correct angular distortion on butt joints
A) weld with one pass
B) weld with many passes
C) weld on both sides
D) Allow the plates to move freely
C) weld on both sides
How can you reduce longitudinal distortion?
A) keep weld reinforcement to a minimum
B) weld on one side of the joint only
C) use slow welding speeds
D) avoid back stepping
A) keep weld reinforcement to a minimum
What is one method to reduce transverse distortion?
A) use a slow deposition rate
B) use a fast deposition rate
C) align the plate so that the space between them decreases along the length of the weld
D) before welding set the plates closer together than you need for the finish weld
B) use a fast deposition rate
What is a disadvantage to rigid clamping and fixturing?
A) set up time slows down production
B) some distortion can occur after releasing the clamping
C) rigid clamping, and fixturing material is expensive
D) this method cannot be used on objects with square corners
B) some distortion can occur after releasing the clamping
What is one advantage of a jigging device?
A) it prevents shrinking of parts
B) it allows for welding in all positions and reduces productivity
C) it, maintains accuracy of the finished product
D) it prevents uneven contraction
C) it, maintains accuracy of the finished product
Pieces of metal placed on either side of the joint that absorbed the heat of the weld and help prevent distortion are called
A) plate clamps
B) weld positioners
C) chill strips
D) back up bars
C) chill strips
What is the purpose of balancing welds around the neutral access of a worn shaft?
A) to equalize the contractions stresses of the welds
B) to increase the heat buildup into the shaft
C) to get more uniform weld build up
D) to allow the use of larger electrodes
A) to equalize the contractions stresses of the welds
How can you help control distortion when welding light gauge metal
A) increase the preheat temperature
B) decrease your welding speed
C) increase the number of tacks
D) maintain a 90° electrode inclination
C) increase the number of tacks
Which fillet weld application produces the greatest amount of distortion
A) staggered intermittent fillet welds
B) a small fillet weld with a concave profile
C) fillet welds produced with one continuous past
D) multi pass fillet welds with a convex profile
D) multi pass fillet welds with a convex profile
What is one characteristic of a good welding design?
A) it uses many rapid changes in cross-section
B) it uses formed or roll sections
C) it uses as many small pieces as possible
D) it uses vertical and overhead position weld as much as possible
B) it uses formed or roll sections
When several plates must be welded together with butt joints, what is the best weld sequence to control distortion?
A) weld from the outside edges and toward the centre in both directions
B) weld from the corners and toward the centre in all directions
C) weld in concentric circles toward the centre without back stepping
D) weld from the center, and toward the outside in both directions
D) weld from the center, and toward the outside in both directions
What is the advantage of using sub assemblies?
A) they provide more welds in the flat position
B) they provide for more welds in vertical and overhead positions
C) jigs, and skeleton frames are not necessary
D) they eliminate the need for formed or rolled sections
A) they provide more welds in the flat position
All metals, except _____, expand when heated and contract when cooled.
a) Al
b) bismuth
c) titanium
d) copper
b) bismuth
List 3 types of expansion
Solid expansion
Transitional expansion
Fluid expansion
_____ expansion occurs in metal that is in a solid state and has not reached its transition temperature.
a) Solid expansion
b) Transitional expansion
d) Fluid expansion
a) Solid expansion
_______ expansion takes place when metal changes from one crystalline structure to another while it is still a solid
a) Solid expansion
b) Transitional expansion
d) Fluid expansion
b) Transitional expansion
____ expansion occurs during the change from a solid to a
a) Solid expansion
b) Transitional expansion
d) Fluid expansion
d) Fluid expansion
When metal is welded, it transitions through all three types of expansion starting with ____ expansion.
a) Solid expansion
b) Transitional expansion
d) Fluid expansion
a) Solid expansion
A body of metal that is heated evenly and is allowed to expand freely in all directions and then is allowed to cool freely returns to its original shape when it reaches its original temperature.
Above describes what type of expansion/contraction?
a) Solid expansion
b) Transitional expansion
c) Fluid expansion
d) Free expansion
e) Free contraction
d) Free expansion
- sometimes called volumetric expansion
If a metal is heated and is restrained in one direction, it is forced to expand more in other directions, and it does not return to its original shape. This condition is known as _______
a) upset
b) distortion
a) upset
What is a special tool for removing broken bolts
an easy out
______ is the result of stresses being set-up in the work through heating, coupled with factors such as expansion, upset and contraction.
a) malformation
b) deformation
c) upset
d) distortion
d) distortion
What are the three types of distortion
Angular
Transverse
Longitudinal
What type of distortion fits this description:
- Is a rotation around the weld line.
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
a) Angular distortion - causes warpage
What type of distortion fits this description:
- is perpendicular to the weld line.
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
b) Transverse distortion - dimensional distortion ( dimensions change due to the contraction of the weld)
What type of distortion fits this description:
- occurs parallel to the weld line.
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
c) Longitudinal distortion- dimensional distortion ( dimensions change due to the contraction of the weld)
_____ distortion is most prominent on Tee joints and butt joints that are welded on one side only.
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
a) Angular distortion
Angular distortion is greater on single Vee groove butt joints than on single U groove due to more weld metal
True or False
True
_____ distortion refers to the tendency in butt joints for the plates to draw together down the length of the joint as you are welding.
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
d) Transverse upset
b) Transverse distortion
A _________ increases the likelihood of transverse distortion: a faster rate helps to control it.
a) faster travel speed
b) slower travel speed
c) faster deposition rate
d) slower deposition rate
d) slower deposition rate
To prevent transverse distortion faster deposition rates are used.
What is another method.
1. Faster deposition rates
2.
Place a wedge ahead of the joint to hold the plates apart.
This acts like a tack weld without affecting metal composition
_____ refers to distortion or shrinkage along the length of the weldment.
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
d) Transverse upset
c) Longitudinal distortion
Longitudinal distortion is particularly noticeable in long welds along strips of steel.
This distortion results in an overall ______ in the length of the weld
a) increase
b) decrease
c) width increases
d) width decreases
a) increase
True / False
You can reduce longitudinal distortion by keeping the reinforcement on groove welds and the convexity of fillet welds to a minimum.
True
True / False
Longitudinal distortion can be somewhat controlled if the heat input is evenly distributed on both sides of the weld and if you use high welding speeds.
True
Distortion can be controlled with what 3 methods?
mechanical
procedural
design methods
List 3 examples of mechanical methods of controlling distortion
All of the below are correct
- jigs and skeleton frames,
- strongbacks,
- pre-setting and pre-bending,
- rigid clamping and fixturing,
- chill strips,
- backing strips and
- sub-assemblies.
You can make allowances for distortion by _____ the parts to allow for the shrinking pull of the weld.
a) prebending
b) widening the root opening
c) presetting the plates
d) both a & c
d) both a & c
pre bending and presetting refer to the same process however pretending often uses clamps to restrain the pieces.
What is an alternative to prebending/presetting plates?
Rigid clamping & fixturing
The greater the restraint against contraction is, the greater the ______ that are induced
a) Angular distortion
b) Transverse distortion
c) Residual stresses
d) Transverse upset
c) Residual stresses
Does restraint also increase the possibility of cracking once the welds have cooled. Y/N
Yes - restraint also increases the possibility of cracking once the welds have cooled
________ refers to the buildup of internal stresses within either the weld or the parent metal
a) Angular distortion
b) Transverse distortion
c) Residual stresses
d) Transverse upset
c) Residual stresses
Using a jig has what 3 main purposes?
accuracy
uniformity of product
cost reduction by increased production.
A skeleton frame is an ______ or ______ which parts are clamped or otherwise held in place for welding.
a) skeleton outer frame, & internal frame
b) skeleton internal frame, skeleton outer frame
c) internal frame, skeleton outer frame
d) both a & c
d) both a & c both describe the same components
A _______ is a heavily built, high-strength object placed opposite the parts to be welded. The parts may be clamped directly to the ______ to maintain alignment.
a) adjustable, positionable vice
b) strong back
c) skeleton frame
d) jig
b) strong back
______ are heavy strips of metal that are placed on either side of the weld shoulders and are generally clamped to a heavy backer. ____ are most often used on welded light gauge sheet metal fabrications.
a) adjustable, positionable vice
b) strong back
c) chill strips
d) jig
c) chill strips
Can chill strips also be used as an alignment jig?
Yes especially when using angle iron as clamps have a secure surface to grab onto
________ are strips of metal or other material that are placed at the back (root) side of groove weld joint preparations.
a) backing strips (backers)
b) strong back
c) chill strips
d) jig
a) backing strips (backers)
Are backers placed on the root side or the cap side of the weldment?
root side
To help reduce distortion, it is always advisable to break the work into a number of component parts and weld these parts first before attaching them to the main assembly.
The term for this description is:
a) component assembly
b) sub-components
c) sub-assemblies
d) fixture assembl
c) sub-assemblies
The principle behind ______ is that the shrinkage forces set up by one weld are counteracted by the shrinkage forces in subsequent welds.
* procedural methods
* WPS
* WSP
* welding specifications
- procedural methods
What are the top 3 procedural methods
- planning the welding sequence
- welding at a fast and even rate of travel,
- pre-set and joint preparation
Below are the other methods - welding around the neutral axis, stagger welding,
- skip welding, back step welding, tack welding,
- using fewer weld passes,
- preheating the work and
- specialized equipment.
A _______ is the order in which the welds of a structure or project are completed.
* direction of weld travel
* order of directions
* welding sequence
* WPS
- welding sequence
What are the top 3 welding sequence guidelines?
- Decide on the direction of each weld. Generally, it is best to work from the centre outwards in both directions. Weld short seams before longitudinal seams are tacked.
- Decide what the proper joint preparation should be.
- Avoid an excessive number of weld passes.
Below are the other guidelines to consider - Choose the type of distortion control (welding around neutral axis, back stepping, stagger welding or skip welding).
- Consider whether the joints are free to move or should be rigidly tacked.
Decide whether pre-setting, pre-bending or pre-heating is needed. - Weld butt joints before lap joints.
- The type of material may affect your decision in some respects (pre-heat or post-heat).
The center of the tank bottom is at what location
a) 1
b) 2
c) 3
d) 4
a) 1
The welding for this tank bottom would proceed
a) outwards from center, long seams before short seams
b) towards center, long seams before short seams
c) outwards from centre & short seams before long seams
d) towards center, long seams before short seams
c) outwards from centre & short seams before long seams
By planning a welding sequence in such a way that one weld pull is counteracted by another weld pull in the opposite direction, you are working around the _________
a) horizontal axis
b) vertical axis
c) radial axis
d) neutral axis
d) neutral axis
The _______ is the theoretical centre of an object or an imaginary line where neither tension nor compression would exist if the object were bent.
a) horizontal axis
b) vertical axis
c) radial axis
d) neutral axis
d) neutral axis
One of the most common examples of working around the neutral axis is building up worn shafts.
True or False
True
Welding in a continuous spiral around a worn roller offers a more even distribution of heat and thus less distortion and less softening of roller flanges.
True or False
True
The principle involved in _____ is the spreading of heat throughout the joint.
a) spiral welding
b) stagger welding
c) skip welding
d) back step welding
b) stagger welding
With ______, weld deposits are applied in increments on each side of the centre of the joint.
a) spiral welding
b) stagger welding
c) skip welding
d) back step welding
c) skip welding
With the _______ method, the first weld begins a short distance from the end with the direction of travel toward that end.
a) spiral welding
b) stagger welding
c) skip welding
d) back step welding
d) back step welding
On long seams, ______ can be controlled by starting the weld a short distance in from the end of the joint and making a short weld first
a) Angular distortion
b) Transverse distortion
c) Longitudinal distortion
d) General distortion
d) General distortion
What are the top 2 guidelines when deciding on the number and frequency of tack welds.
- The thinner the material the closer the tacks should be
- narrow strips require more tacks than wide strips
- flat objects require more tacks than cylindrical pieces
On butt joints, which weld is preferable over a Vee preparation
a) double V-Groove
b) single U-Groove
c) double U- Groove
d) single bevel
single U-Groove as it requires less weld metal to fill the joint
Avoid too many passes when welding because this heating and cooling leads to higher _____.
a) risk of weld cracking
b) porosity
c) distortion
d) inclusions
c) distortion
True or False
One pass performed at a high current setting results in less distortion than depositing several passes.
True
One large pass results in more
a) shrinkage
b) coarse grain structure
c) fine grain structure
d) distortion
b) coarse grain structure
however, you have to strike a balance between number of passes versus grain structure; *a few smaller passes is better than one large or many very small passes.
Weld at a fast, even rate of travel to keep the HAZ narrow and to prevent too much heat from creeping ahead of the weld.
The slower the speed is, the more the heat creeps ahead and the higher the ________ is.
a) shrinkage
b) coarse grain structure
c) fine grain structure
d) distortion
d) distortion
Distortion can be neutralized if you apply a _______ directly opposite where you weld the coupling. Preheat about the expected width of the heat-affected zone caused by welding.
a) flame
b) general preheat
c) local preheat
d) post heat
c) local preheat
A water-jet cutting machine requires no heat input and can cut _______ materials easily. Because no heat is put into the work, there is no uneven cooling.
a) ferrous
b) non- ferrous
c) both ferrous & non ferrous
c) both ferrous & non ferrous
A good design for welding contains the least possible number of pieces and the _____ of weld metal.
a) maximum
b) minimum
c) amount of weld material doesn’t matter only the amt of heat imposed
b) minimum
Is it preferable to use round or square corners?
round - this prevents a change in direction of the stress flow lines which causes a notching effect
If you are joining materials of significantly different thicknesses, use a______ transition to smooth out rapid changes in cross-section.
a) staggered
b) tapered
c) stacked
d) dovetail
b) tapered
Note:
The welds run in line or longitudinally with the frame. Do not weld on the ends or across the carrying members. Welding across the frame can set up high stresses that can lead to cracking when the frame is stressed or loaded.
When stacking multiple sections of sheet metal to create a cylinder would you stack them in line with the next or staggered like bricks?
Staggered
When a job is clamped to control distortion, the weld area will always: (10)
* have high residual stress
* retain a brittle heat effected zone
* have an austenitic grain structure
* be subject to undercut due to bead contraction
- have high residual stress
Which of the following will usually produce the greatest amount of distortion? (6)
* one pass in a square groove butt x
* two passes on a double vee butt
* three passes on a single U butt
* four passes on a double lap fillet
- three passes on a single U butt
A procedural method of reducing distortion would include:(14)
* welding at a fast and even rate of travel
* pre-setting and joint preparation
* planning the weld sequence
* all of the above
- all of the above
When a metal is heated and restrained in one direction it will return to its original shape. (3)
True / False
False
The most important reason for rounding corners, transitioning, or tapering, on structural components is to:
* reduce injuries
* reduce distortion
* enhance the look of the design v
* prevent rapid change in stress flow lines
- prevent rapid change in stress flow lines
Another method of reducing distortion is to tack sub-assembly parts and main assembly parts as one complete component and then weld. (13)
True / False
False
The reason for staggering welds is to: (17)
* increase the weld strength the joint
* reduce the quench effect of the joint
* increase the production rate of welding
* spread the welding heat throughout the joint
- spread the welding heat throughout the joint
Angular distortion would be greater on a single Vee groove weld than a single U groove weld. (6)
True / False
True
Welding around the neutral axis: (16)
* increases welding production
* allows for even heat distribution
* reduces internal stress in the weld
* prevents heat build-up in the parent metal
- allows for even heat distribution
How can distortion be minimized when welding thread o-lets on a piping header? (21)
* by quenching the weld after every pass to minimize distortion
* by applying local preheat opposite the weld location
* allow cooling in air between each weld pass
* using larger electrodes and less passes
- by applying local preheat opposite the weld location
Excessive reinforcement on the surface of a weld could result in: (8)
* angular distortion
* transverse distortion
* transitional distortion
* longitudinal distortion
- longitudinal distortion
The three types of expansion encountered in welding are: (2)
* solid, transverse, fluid
* solid, transitional, fluid
* solid, transitional, transverse
* transitional, transverse, longitudinal
- solid, transitional, fluid
The recommended procedure for welding the courses on a storage tank, is to align the circumferential and longitudinal seams to reduce distortion. (23)
True / False
False
Which of the following would help to minimize distortion? (20)
* weld at a fast, even rate of travel
* increase the number of weld passes
* use maximum weld reinforcement
* use multiple stringer passes instead of weave beads
- weld at a fast, even rate of travel
A large pass of weld metal always improves production when compared to multiple small passes, but the disadvantage can be: (20)
* a coarse grain structure for one large weld pass
* a finer grain structure for one large weld pass
* less distortion for the multi-pass welding x more * distortion for one large weld pass
- a coarse grain structure for one large weld pass
A mechanical method for minimizing distortion is: (9)
* a jig and skeleton frame
* a general preheat of the joint area
* tacking at short intervals and back stepping
* done by decreasing the number of weld passes
- a jig and skeleton frame
Angular distortion occurs most commonly on: (6)
* tee joints welded on one side
* tee joints welded on both sides
* butt welds welded from both sides
* all of the above
- tee joints welded on one side
The recommended procedure for reinforcing a frame would be to: (22)
* weld the vertical ends of the reinforcement
* weld intermittently all around the reinforced plate
* weld only along the longitudinal section of reinforcement
* weld continuously all around the reinforced section of plate
- weld only along the longitudinal section of reinforcement
The expansion of metal when heated, and contraction when cooled, can be an advantage when: (4)
* welding cast iron
* controlling distortion
* removing broken studs
* welding couplings on a header
- removing broken studs
One purpose of a permanent backing strip would be: (13)
* a temporary backer used for tacking purposes
* to prevent distortion by maintaining joint alignment
* a backer used to fill gaps and reduce the amount of weld passes
* to prevent weld defects due to atmospheric contamination
- to prevent distortion by maintaining joint alignment
Which of the following metals will not expand when heated? (2)
* iron
* copper
* bismuth
* Aluminum
- bismuth
When solid metal changes from one crystaline structure to another it is referred to as: (2)
* transitional expansion
* transverse expansion
* solid expansion
* fluid expansion
- transitional expansion
What is the name of the pieces of metal placed on either side of a joint to absorb heat from the weld used for preventing distortion. (12)
* rollers
* clamps
* chill strips
* weld positioners
- chill strips
When a metal is heated evenly and allowed to expand freely it will return to its original shape. (2)
True / False
True
What is the purpose of balancing welds around the neutral axis of a worn shaft? (15)
* to equalize the contraction of the weld area on the shaft
* to apply more heat to the shaft thus reducing distortion
* to allow the use of larger electrodes
* to get a more uniform build up
- to equalize the contraction of the weld area on the shaft
Multi-pass welds will result in: (20)
* excessive buildup
* incomplete fusion
* internal undercut
* more distortion
- more distortion
A large heavy piece of metal, used to clamp parts, for alignment purposes is called a: (12)
* jig
* skeleton
* strongback
* parent metal
- strongback
Restraining expansion during the heating process will produce which of the following after cooling? (4)
* upset
* internal stress
* internal cracking
* surface hardening
- upset
When fusion welding metal which type of expansion occurs? (2)
* fluid
* solid
* transitional
* all of the above
- all of the above
Jigging devices will: (10)
* speed up production
* increase the need for a helper
* hinder mobility and functionality
* decrease the assembly productivity
- speed up production
