Emc Practice Flashcards
(163 cards)
1
Q
Ultrasonic inspection of casting is difficult due to
A
The grain structure attenuating the sound beam
2
Q
After solidification of a casting, the “as-cast” structure consists of a chill layer and elongated grains growing in towards the center. The elongated grains are called
A
Columnar grains
3
Q
In the casting process, pouring the molten metal in through two pour basins can lead to
A
A defect known as cold shut
4
Q
The bottom portion of a molding flask is called a
A
Drag
5
Q
An approved model or a “recommended practice” not enforced by law is known as a
A
Standard
6
Q
A commonly used method of not which utilizes acoustic energy at frequencies above the audible range is
A
Ut
7
Q
Casting defects are caused by
A
Incorrect metal composite
bad melting or pouring procedures.
Poor pattern design
Incorrect composition of molding and core sand.
Incorrect positioning of runners, risers, gates and poor molding practice. (All of the above)
8
Q
Trapped gas in a casting mold cavity may cause
A
Porosity
9
Q
The hardness testing method that utilizes a 120° diamond tip indenter with a 10 kg minor and 150 kg major load is the
A
Rockwell c hardness
10
Q
The flash in the closed die forging process can fold over and cause
A
A lap
11
Q
Solidification of a metal occurs in two stages. Those stages are
A
Nuclei formation and grain growth
12
Q
Ultimately the function of any ndt inspection is to
A
Find all discontinuities that the proper use of the test method is capable of indicating
13
Q
Cast turbine blades are often inspected with which two ndt methods to detect leading and trailing edge cracks
A
Et and pt
14
Q
What two ndt methods would best detect a lamination in a ferromagnetic material
A
Ultrasonic inspection and magnetic particle inspection
15
Q
Discontinuities that result from trapped impurities in a material when it solidifies from molten state are
A
Inherent
16
Q
Seamless tubing can be automatically inspected at rates up to several hundred feet per minute using which ndt method
A
Eddy current testing utilizing encircling coils
17
Q
A Crack or fracture in a casting due to the segregation of low melting point impurities in combination with the restraint from the mold is known as
A
Hot tear
18
Q
Elongated configurations of foreign substances aligned in the direction of working commonly found in lengths of bar stock are called
A
Stringers
19
Q
Identify a processing method that can effect a materials mechanical properties
A
Welding
20
Q
Care must be taken not to splash molten steel on the walls of the mold when pouring to prevent formation of surface defects like
A
Cold shots
21
Q
Slag inclusions in welds are caused by
A
A wide weave pattern and incomplete removal of Slag from previous passes
22
Q
Where is the most logical place on a casting to look for discontinuities
A
At junctions between light and heavy sections
23
Q
A wrought iron used in forging process can be called a
A
Bloom, billet or slab
24
Q
What are the three types of stress
A
Tensile, compressive, shear
25
Which discontinuities is not normally associated with a casting but found in forging
Burst (found in forging)
26
Bursts are caused by
Forging metal which is too hot
27
A form of localized corrosion that can Penetrate deep into the material is known as
Pitting
28
A welding defect that occurs on each side of the root pass and runs parallel with the Weld is
Incomplete joint penetration
29
Improper cleaning, insufficient preheating of a weldment, moisture on the base metal, or moisture on the filler metal could cause
Porosity
30
The following defect is caused when the internal edge (or land) of the bevel preparation is left and is not incorporated into the root pass
Lack of fusion
31
A common method of ndt used to detect fatigue cracks open to the surface on aluminum aircraft part is
Lpi
32
The ndt method commonly used to inspect thin wall heat exchanger tube is
Eddy current inspection
33
Which of the following heat treatments usually follows a hardening treatment in order to restore toughness and ductility to the steel
Tempering
34
The difference between an annealing and a normalizing is
The cooling rate used
35
What are the three main types of space lattices
BCC, FCC, HCP
36
Carbon steels used to produce plate, pipe and wire with a carbon content between 0.06% and 0.25% are also referred to as
Low carbon steel
37
The two methods of component failure are
Fracture and permanent deformation
38
What happens to atoms when metals solidify
Atoms lose mobility and assume fixed positions in the space lattice of the unit cell
39
When a metal is stressed beyond its elastic limit, after the stress is released it has
Permanent deformation only
40
Etching, pickling and plating cracks are all caused by
The evolution of hydrogen which permeates the grain boundaries causing cracks
41
Cold working metals increase their
Hardness and strength
42
Of the following which method produces most of the world's steel today
Basic oxygen furnace
43
A difference between shielded metal arc welding and gas metal arc welding is that in gas metal arc welding
A stream of protective gas is passed through a nozzle which surrounds the electrode
44
One method of ndt that has been used to monitor the initiation and growth of stress corrosion and hydrogen embrittlement cracks in astenitic stainless steel is
Acoustic emission
45
Recapitalization temperature is the temperature at which
A cold worked structure will recrystallize in 1 hour
46
To remove iron from the ore in a blast furnace, which materials are added to generate the desired chemical reactions
Coke, ore, limestone and air
47
Contrary to fusion welding, resistance welding
Requires the application of pressure to achieve complete bonding
48
A crater Crack may occur when
The welder fails to fill the crater before breaking the arc
49
Shielded metal arc welding is a process of joining two metals and is performed _____
Performed manually
50
Suitable combinations of two different materials, each with specific properties may result in a composite that
Has better resistance to heat than the individual materials. Is stronger in tension than the individual materials. Is stiffer per unit weight than the individual materials.
51
An increased amount of energy at the grain boundaries after cold working leaves them susceptible to a type of intergranular corrosion known as
Stress corrosion cracking
52
A finshing discontinuity that bears no relation to the direction of metal grains is
Grinding cracks
53
A burst is what type of discontinuity
Processing (forging)
54
Where is the most logical place in an "as cast" ingot to look for porosity
In the top section
55
In the submerged arc welding process, Flux is added ______
separately and heaped along the joint being welded
56
The most common method for producing steel seamless tubing involves
Piercing round billets with large diameter and short length
57
Magnetic particle inspection can most effectively be performed on what type of material
Any ferromagnetic material
58
Any interruption in the normal physical structure or configuration of a test part, which may or may not affect the usefulness of the part, is called a
Discontinuity
59
Discontinuities created during the additional processing of metals, such as forging, rolling or welding are categorized as
Processing discontinuities
60
A commonly used method of ndt which utilizes acoustic energy at frequencies above the audible range is
Ut
61
Fracture is one type of material failure. what is another type of material failure
Permanent deformation
62
Ultrasonic inspection can be used to
Determine material thickness from one side only
63
From an engineering and inspection standpoint, what defects is considered the one of the more detrimental
Fatigue crack
64
Eddy current is most commonly used to detect defects in
Thin materials
65
The most frequently used method of ndt is
Visual testing
66
The ndt technique may be selected by the level 2 technician, but the test method, test procedures and instructions to be used are determined by the
Level 3
67
One main advantage of Eddy current inspection over the other test methods is
It is a very rapid inspection since it does not need to contact the test piece
68
Ultimately the function of any ndt inspection is to
Find all discontinuities that the proper use of the test method is capable of indicating
69
A discontinuity that is of such a size, shape, type or location that it creates a substantial chance of material failure is known as a
Defect
70
The three main categories of defects are
Inherent, processing, service
71
A very effective way to help eliminate or control the human factors that can cause human error is to
Properly educate and train new personnel
72
An approved model or a "recommend practice" used in manufacturing, and is not enforced by law is known as a
Standard
73
When a technician deems an indication to be relevant, what is the next step
Evaluate the indication to a pre-determined acceptance criterion to determine severity
74
The standard used in Canada to certify ndt personal is
Can/cgsb 48.9712
75
For fatigue cracking to occur, what type of stress is required
Cyclic and tensile
76
Lpi is limited to what type of defect
External
77
When one "weak" component fails, and the remaining load must be absorbed by neighboring component a ___________ type fracture may occur
A progressive type fracture may occur
78
The two most used types of sound waves used in industrial ultrasonic inspection are
Longitudinal and transverse (shear)
79
Xrf is a method of ndt commonly used for
Material identification and sorting, detects relative amounts of alloying elements in metallic alloys, detecting heavy metal content in polymers or coating (all of the above)
80
The three key activities that must be completed in order to become a certified ndt technician in Canada are
Apply for certification, complete QWE and vocational training, and pass the certification examinations
81
Two main classification of metals
Ferrous and nonferrous
82
Iron has the ability to exist in more than one type of crystal lattice in the solid state. This phenomenon is known as
Allotropy
83
After solidification, the structure of the outside surface of a casting usually consists of
Fine equiaxed grains having random orientation and shape
84
After solidification of a casting, the "as-cast" structure consists of a chill layer and elongated grains growing in towards the center. The elongated grains are called
Columnar grains
85
Solidification of a metal occurs in two stages. Those stages are
Nuclei formation and crystal growth
86
Ultimate tensile strength is defined as
The maximum stress in a tensile test
87
The initial slope of a stress strain diagram within the elastic region indicates the rigidity of material. This property is referred to as
Modulus of elasticity
88
What are the three types of stress
Tensile, compressive, shear
89
What are the two types of solid solutions
Interstitial and substitional
90
Typically, fine grained metals exhibit better
Mechanical properties
91
Yield points indicates
Stress value at the beginning of the plastic range
92
Thermosetting polymers have _________ carbon atoms providing a second degree of polymerization making it harder, stronger than commodity thermoplastics
Cross linked
93
Which chemical bond is considered to be the strongest
The ionic bond
94
What is the primary element in ferrous metals and alloys
Iron
95
Ceramics are typically non-metallic solids with good
Wear resistance
96
A common example of a composite is
Carbon fiber reinforced polymer panels
97
A common use for ceramic material is
Refractory brick for insulating the walls of a furnace
98
An alloy is substance composed of
Two or more elements, of which at least one Is a metal
99
The characteristic "tree like" pattern that occurs during crystal growth is known as
Dendrite
100
The two common isotopes used in gamma rt are
Cobalt and iridium
101
Which hardness testing method uses a 120° diamond tipped indenter with a 10 kg minor load and a 150 kg major load
Rockwell C hardness testing
102
Plastic deformation refers to
The permanent deformation of a specimen
103
Magnetic properties refer to how a material will be influenced by a Magnetic field, and this material property is considered a
Physical property
104
When a component is subjected tensile stress below the yield strength of the material
That component will fail after a sufficient number of cycles due to fatigue
105
Large casting called ingots must go through primary rolling mills to produce slabs, blooms and billets. Which of these rolled products will have a cross sectional area less than 36 in squared
Billet
106
The removal of impurities and flaws from the top section of a cast ingot prior to mill working is called
Cropping
107
Carbon steels used to produce plate, pipe and wire with a carbon content between 0.06% and 0.25% are also referred to as
Low carbon steels
108
Which ndt technique would be most suitable for the examination of an austenitic stainless steel (304) shaft to detect any fine fatigue cracks on the surface
Liquid penetration test
109
a precision casting method used to produce complex aircraft parts generally weighing less than 1 kilogram is
Investment casting
110
Which method produces most of the world's steel today
Basic oxygen furnace
111
In a sand-casting mold, the sprue connects the
Pouring basin to the runner
112
Which type of corrosion tends to occur at metal-gasket interfaces
Crevice corrosion
113
A metal production process which eliminates the need for ingot cropping is
Continuous casting
114
When using a green sand mold, the moisture used to bind the sand can lead to what surface discontinuity
Porosity
115
A formal of localized corrosion that can penetrate deep into the material is known as
Pitting
116
Where is the most logical place to look for a hot tear on a casting
At junction between light and heavy sections
117
In the casting process, pouring the molten metal in through two pour basins can lead to
The defect known as cold shut
118
The two major categories of aluminum alloys are
Wrought alloys and cast alloys
119
All forging methods can be categorized into two major groups. They are
Open die forging and closed die forging
120
During metal forming, metals will develop higher strength in the direction of rolling due to strain hardening. This unequal strength of the grains is known as
Anisotropic properties
121
To remove iron from the ore in a blast furnace, the following materials are added to the furnace to generate the desired chemical reactions
Coke, ore, limestone, and air
122
The term "pipe" refers to
The central shrinkage cavity in an ingot
123
When a casting requires more than one parting section, a middle section is added between the upper and lower halves of the casting mold. These three sections are called
Cope, check, and drag
124
The controlled heating and cooling of a metal, in solid state, to achieve desired properties is called
Heat treating
125
Hydrogen accumulating in a steel structure can cause the steel to fail in a brittle fashion. This phenomenon is known as
Hydrogen induced cracking
126
A metal support for holding cores in place within a sand mold is called
A chaplet
127
In galvanic corrosion, the least noble metal (the anode) in the metal will
Corrode
128
A casting mold may be designed to contain external risers and internal risers. The main purpose of these risers is to
Supply liquid metal as needed to compensate for shrinkage before solidification is complete
129
To help eliminate or control the cooling rate of "hot spot" in a casting
Chills may be placed inside the mold to help control cooling rates
130
List 6 discontinuities
Cracks
Voids
Inclusions
Desalination's
Dis-bond's
Corrosion
131
Difference between the terms "method" and "technique" when used in relation to ndt
Method- the collection of the inspection techniques, based the inspection energy used
Technique- the specific way in which that the inspection energy is applied or detected
132
What is two limitations of pt, Mt, rt
Pt- surface condition and pre-cleaning techniques greatly effect test results as the penetrant mist have some way of entering the discontinuity( temperature limitation)
Mt- part geometry, material limitation and the need to demagnetize after inspection
Rt- access to both sides of the piece is required. Density and the orientation of the discontinuity is crucial to detection. Safety
133
List four benefits of using ndt to inspect a manufactured product
Avoids failure and prevent accidents by ensuring product Integrity and reliability
Ensure costumer satisfaction and maintain the manufacturer reputation
Aid in product design and control manufacturing process
Lower manufacturing costs and make more profit for user
134
What is a inherent discontinuitie
These discontinuities are related to the solidification of the molten metal. They may be formed during the original solidification of the ingot or during the melting, casting and solidification of metal later in the fabrication process
135
What is a processing discontinuity
These discontinuity are related to or occur during the various manufacturing process. This group generally has two sub categories. Primary processing discontinuities and secondary processing discontinuity
136
What is a service discontinuity
Related to various service conditions to which the part is subject to eg fatigue stress corrosion and erosion
137
What is a relevant indication
Indication formed because of a discontinuity present in the test object
138
What is non-relevant indication
Indication that is un related to a flaw in the test object. Formed by some other factor. The Indication could be due to part geometry, surface condition or a change in metallurgical structure
139
What is a false indication
Indication formed by misappropriation of the test method or technique
140
Identify and describe the 4 types of crystal imperfections that are influential on a metals ductility
Vacancy- the lattice has atoms missing or has extra atoms
Interstitial's- tend to push the surrounding atoms farther apart and distort the lattice planes resulting in increased resistance to plastic deformation
Edge dislocation- atoms above the dislocation line are compressed, while those below are forced apart
Screw dislocation- the lattice is distorted down through the lattice in a spiral format
141
Iron is an allotropic metal. Which crystal structure would iron be in for 20°c-912°c, 912°c-1394°c, 1394°c-1538°c and above 1538°c
20°c-912°c: bcc
912°c-1394°c: fcc
1394°c-1538°c: bcc
Above 1538°c: liquid
142
Explain the purpose of impact testing and identify the two types of temperatures being determined during Impact testing
It is used to determine the materials susceptibility to undergo brittle fracture (toughness).
The two types of temperatures are:
fracture appearance transition
temperature and energy criteria transition temperature.
143
What are four effects that solid solution strengthening could have on the properties of a material
Corrosion resistance
Strength at high temperatures
Ductility of alloys is lower
Solidification temperature can be significantly changed
Increased electrical conductivity
144
Steel is defined as
Iron with a small amount of carbon introduced creates steel
145
Explain the difference between thermosetting and thermoplastic polymers
Thermoplastic polymer- higher in toughness, they have lower strength and hardness (Vander bond)
Thermosetting polymers- high hardness, high strength, good corrosion (covalent bond)
146
Explain the difference between a material yield strength and ultimate tensile strength
Yield strength- is the stress required to produce a specific amount of plastic strain
Ultimate tensile strength- is the maximum stress reached in the tensile test
147
What are the 4 major categories of corrosion and give examples of each
Uniform corrosion- rust on cars
Localized corrosion- galvanic, cervice, pitting, integranular and de-alloying
Erosion corrosion- on metal tubes contacting water
Environment cracking- metals under stress causing hairline cracks
148
Describe the following discontinuities
Cold shut
Molten metal is poured from two directions, allowing the mold to be filled at a faster rate.where the two flowing channels meet, there is a chance one is cooler than the other and complete fusion does not take place
149
What is a hot tear
Uneven cooling in thin or on corners that adjoin to heavier masses of metal can result in hot tears if a section begins to shrink while still hot and there is not sufficient supply of liquid metal, the internal stress tear the metal apart.
150
What is inclusion
These are normally oxides or sulfides that are nonmetallic in nature and are located within the solid metal structure and are extremely brittle, which can cause the formation of cracks if stresses are impose on the casting
151
What Is a rolling seam
Open continues lines that run along the length of the metal and caused by under filling in the rollers. Seams can also occur when cracks on the slab billet are stretched out and lengthened during the rolling process (rolling discontinuities)
152
What is a lamination
A discontinuity normally aligned parallel to the rolling direction and surface of the plate. Maybe the result of Pipe, blister or inclusion that are thinned and spread out by the flattening action of rolling (rolling discontinuities)
153
What is a flash line tear
As the dies close in the final stages of the forging process, the flash must be removed by trimming dies. If the trimming is not done properly, cracks or tears can occur along the flash line where the two die halves meet. (Forging discontinuities)
154
What is core shift and how can it be detected by nde?
Core shifting during casting process. usually defects can be found using rt
155
How does grain structure (grain size, grain orientation and grain boundary composite) affect some ndt methods such as RT and UT
Large grain structure can cause diffraction effects wich reduce image quality.
Course grain structure makes UT inspection a challenge
Reflection off the grain boundaries and attention caused by large grains can make interpretation of results extremely difficult and may lead to false indications
One challenge of UT and not for rt is the rough surface often present on casting can make coupling difficult.
156
What is the sprue in a casting mold
The mold Chanel the pouring basin with the runner. In a sand mold an opening in the sand that is made by a spruce pin that's on the top surface
157
What is a runner in a casting mold
An internal Chanel that will allow unrestricted access for the passage of the molten metal
158
What is the gate in a casting mold
The portion of the runner in a mold through which molten metal enters the mold cavity
159
What is a riser in a casting mold
Also called a feeders, are reservoirs located in the sand mold that provide additional metal to the parts of the casting that freeze last of all
160
What is a core in a casting mold
When a hole or cavity is required in a sand casting, it is usually made by inserting a specially made sand core
161
What is a chaplet in a casting mold
Whenever a core is either long or fragile, a chaplet is inserted. A chaplet is designed to support the core, and this is made of the metal that is being cast
162
What is a chill in a casting mold
Often large changes in thickness cannot be avoided. Therefore controlling the cooling rates must be accomplished to ensure product quality. To assist with controlling the cooling rates, chills may be incorporated into the casting itself or in the mold.
163
Explain two advantages of cold working versus hot working a metal
Good surface finish with no oxide scale.
Extremely close dimensional tolerance due to no thermal shrinkage
