Canadian Welding Bureau (CWB) Level 3 Practice Exam

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• The oxidation rate of magnesium-containing alloys is ______ than for magnesium-free alloys.
• After oxide removal by mechanical milling or chemical treatment prior to welding, the surface will almost instantly re-oxidize in dry air.
• Oxide removal prior to welding, the surface will form local electrolytic cells between dry and wet sections and the wet part will corrode preferentially, forming a stain.
• Pearlite is a single phase. True or False?
• Which of the following is an example of a substitutional solid solution?
• What structural change occurs in iron when heated above 910 C?
• In a body-centered cubic structure, atoms are assumed to be ____.
• As temperature rises, oxide stability tends to:
• What is referred to as the helix of filler wire?
• Can bainite normally be produced in continuous cooling of a plain carbon steel?
• If the cast is much less than 30 cm, what happens to wire feeding in push wire feed systems?
• Bauxite is extracted by which method?
• Martensite is a phase produced in hardenable steels that are quenched rapidly because the:
• Increasing the carbon content affects martensite by which action on the martensite start temperature (M_s)?
• Shielding required for steel?
• In a 0.6% carbon steel slowly cooled from 900°C, approximately what fraction is proeutectoid ferrite?
• Acicular ferrite in weld metal is
• Shielding required for aluminum?
• Wires for CO2 welding usually contain silicon to
• Between 1390 C and the melting point, what structure does iron exhibit?
• The region where carbon is dissolved in BCC iron is which phase?
• If plates are deformed more than 5% during fabrication, the simple heat treatment often specified to restore ductility is:
• Which two mechanisms enable electrical conduction?
• Which statement best describes the effect of post-weld heat treatment on toughness?
• Steels are alloys of iron with less than ____ % of carbon plus a wide range of other elements
• The gamma phase dissolves up to approximately what percentage of carbon?
• The effect of increasing the carbon content of a steel on the Charpy transition curve is to:
• Gold can be cold welded.
• Which crystal structure is not closely packed?
• Secondary hardening is caused by:
• What are fine grain steels?
• What is the role of magnesium as a surface-active element in aluminum?
• Where is AA-5454 used?
• For a steel with 0.2%C, 0.18%Si, 0.2%Mn, 0.35%Cr, what is the maximum rate of cooling to avoid excessive hardness according to the given data?
• Bainite can be produced in a hardenable plain carbon steel through isothermal transformation. Which option correctly identifies isothermal transformation as the mechanism?
• Elements which form interstitial solutions with iron
• What forms the largest group of commercially important alloys
• Which statement best describes the FCC crystal structure?
• Which statement best describes the effect of rapid cooling on phase formation in steel from the austenite region?
• The melting point of aluminum is about what fraction of the melting point of steel?
• Prior to welding aluminum-lithium alloys, oxide is scrapped off the metal to minimize weld porosity. This statement is:
• What is smut formation in the weld region?
• Which statement correctly compares ferrite and cementite carbon content?
• Shielding required for copper?
• True or false? A post-weld heat treatment (stress relief) always improves the fracture toughness of the HAZ.
• Which statement best describes thermionic emission?
• The oxide transformation from aluminum oxide to magnesium oxide or magnesium spinel has a profound effect on the solid-state bonding between clad and the aluminum base.
• Which metal has melting temperature around 660 C?
• Compared to non-metals, metals are generally known for which mechanical property?
• In GMAW with Mg-free filler, ozone generation is most pronounced with which alloy option?
• A large free energy change for oxide formation indicates the oxide is:
• Why is magnesium kept below 3% in high-temperature applications?
• Compared to pure tungsten electrode, 2% thoriated tungsten electrode has a ______ life.
• What is the general trend for HAZ toughness in steel with respect to heat input?
• Steel of eutectoid composition will, when cooled from the austenitic region, transform at 723 C to form a two solid phase called ______
• Gold and silver are commonly used as which component in electrical systems?
• Which region corrodes preferentially after oxide removal: wet or dry?
• The minimum energy required to free an electron from the surface is called the work function.
• If compressive stress is applied to the solidifying weld bead, what is the effect?
• Adding carbon and nitrogen to iron affects dislocations by
• Which crystal structure is capable of extensive plastic deformation?
• What is the maximum solubility of carbon in iron?
• Which metals are commonly used as electrical contacts due to their conductivity?
• What is the appearance of peritectic on iron carbon diagram
• Eutectic temp of Cu - Silver system
• Which SAW flux combination is associated with very low silicon in the deposit?
• What mechanisms produce ozone in welding fumes?
• Aluminum is typically covered with a coherent oxide film.
• The solid-state bonding between aluminum and another metal or another aluminum alloy generally requires a control of the magnesium level to ____%.
• Solid solutions are _____ phase even though they contain two or more elements.
• Which option correctly lists the two main types of solid solutions?
• Very high thermal conductivity makes arc welding difficult and resistance welding impossible because heat is rapidly removed from the weld. True or false?
• In the heat-affected zone, which region has the highest hardenability?
• In tempering, what is the primary fate of carbon trapped in martensite?
• Which statement best explains why magnesium influences the oxide on aluminum?
• Carbon solubility is greater in FCC iron than in BCC iron.
• Under equilibrium conditions, for plain carbon steel the average composition of pearlite is:
• What are allotropic forms of iron
• Fine grain steels are defined by which feature?
• What is the electrical resistivity of copper?
• Melting temperature of steel?
• What are the two criteria for a weld to become a crack?
• Ozone is a respiratory irritant.
• Carbon solubility in BCC is lower than in FCC.
• In a body-centered cubic lattice, how many atoms are effectively contained in one unit cell, and where are they located?
• Pure copper welding capability?
• Which welding process generates the greatest amount of smoke?
• What statement best describes the primary contribution to the thermal conductivity of metals?
• Which property makes copper a good electrical conductor?
• Under equilibrium, the average composition of pearlite in plain carbon steel is approximately:
• The modulus of elasticity (stiffness) of aluminum is about ______ of the modulus of steel.
• Which has higher electrical resistivity, aluminum or carbon steel?
• Bainite can be produced in a hardenable plain carbon steel through:
• The region in the heat-affected zone that has the highest hardenability is the region with which microstructure?
• What is the work function of thoria?
• Iron extraction method?
• Coarse grain steels are preferred in applications where which property is important?
• Which statement defines eutectic composition?
• Which statement best summarizes the effect of using Mg-free filler alloys on smoke and ozone generation?
• Low reinforcement angle improves fatigue performance.
• Fluxes contain potassium to facilitate which process?
• To minimize ozone generation, which filler alloy is preferred?
• 1XXX series filler alloys, such as AA-1100 and AA-1188, have a tendency to form wormhole defects.
• Ferrite has ________________ amount of carbon
• Which metal has the highest melting temperature among those listed?
• Up to 910 C, iron has which crystal structure?
• What is the max solubility of carbon in BCC iron by weight?
• Which statement is true about eutectoid steel?
• Compared with FCC, BCC has a packing efficiency that is:
• Statement about pure copper welding is accurate?
• The ideal critical diameter is a measure of which property of steel?
• When Mg-free filler alloys are used, what happens to smoke and ozone generation during welding?
• What problem can occur if the welding wire is too straight?
• What is the temperature range over which iron has the FCC structure?
• There will be a range of compositions in which two phases will exist.
• Interstitial solid solutions are formed by very small atoms such as hydrogen, carbon or nitrogen.
• What is the electrical resistivity of aluminum?
• Cu and Al are used as electrical conductors because they have which characteristic?
• The difficulty of welding an alloy crack-free is related to the difficulty of casting crack-free.
• Which statement correctly lists the iron allotropic forms at different temperatures?
• What is an ion?
• Which factor is NOT listed as affecting the degree of protection required during welding?
• What simple heat treatment is widely used to improve the toughness of structural steels?
• The grain growth tends to do what with the surface energy?
• Which phase in iron is also referred to as gamma phase?
• What is the effect of the high fluidity of Al-Si filler alloy on the weld surface reinforcement angle?
• Dislocation locking in iron is achieved by adding which elements?
• At 0.8 wt% carbon, the start of austenite formation occurs at which temperature?
• In AC GTA welding with Mg-free alloys, nitric oxide converts ozone into which gases?
• Which metal can be fused without shielding gas?
• If heat input is increased in steel welding, what is the effect on HAZ toughness?
• Free/conduction electrons are responsible for which properties of metals?
• Which metal is known to have cold welding properties?
• Lead and aluminium have what solubility in each other?
• Easy ionization maintains arc stability during which condition?
• Which oxide is characteristic of lithium-bearing aluminum alloys' surface oxide?
• Ferrite contains very little carbon whereas cementite contains ___% of carbon
• Fluxes in electro slag welding acquire their conductivity primarily due to what?
• Which aluminum alloy has the highest structural strength?
• Does a post-weld stress relief always improve the toughness of a weld metal?
• What causes the austenite grain growth?
• What is the cause for weld bead cracking in aluminum?
• Electrical resistivity of carbon steel?
• Austenite / gamma phase in iron dissolves up to ______ % of Carbon
• Why is martensite produced rather than pearlite when a steel is rapidly quenched from 900°C?
• With no carbon present, austenite starts to form at which temperature
• The plot of free energy of oxide formation is known as the:
• If a thermal stress relief is applied to a welded quenched and tempered steel, the temperature should not exceed the:
• Lead and aluminum have _______ solubility in each other.
• If you wished to obtain a deposit with very low silicon using SAW you would use the combination of a:
• The only strengthening mechanism that will also increase toughness is:
• Equilibrium diagrams don't apply if .....
• What is the melting temperature of lead?
• Which precipitates are commonly cited as pinning austenite grain boundaries in fine grain steels?
• The overall impact of oxide state on welding outcomes for aluminum-lithium alloys can be summarized as:
• Which filler alloy is appropriate for dynamic loading applications?
• The longer life of 2% thoriated tungsten electrodes is primarily due to what?
• The austenite grain size close to the weld interface (fusion boundary) is determined mainly by the:
• To obtain a deposit with very low silicon using SAW, which combination is preferred?
• Which statement correctly describes the unit cell of a body-centered cubic lattice?
• What is the maximum magnesium content in AA-5454 plate alloy?
• Al loses strength with welding.
• The form of magnesium oxide is a function of the magnesium concentration and the thermal history of the alloy.
• Which statement best describes the relationship between oxide phase and bonding at the clad-Al interface?
• From 1390 C to the melting point, iron has which crystal structure?
• Which material requires inert gas with special precautions for shielding?
• Which material has inert gas as preferred shielding?
• Most metals are only stable at high temperatures and a reducing agent is used to lower oxygen potential.
• In a completely solid-soluble alloy across the entire composition range, how many phases exist in the solid?
• Which of the following is an example of a substitutional solid solution?
• Will the use of argon shielding with flux-cored arc welding always ensure a low oxygen deposit?
• If an element has a high ionization potential, what can be inferred about its electrons?
• Aluminum from bauxite cannot be extracted by which method?
• The degree of difficulty to weld an alloy crack-free is related to the degree of difficulty to cast the alloy crack-free either as a DC ingot or a shape casting.
• In HSLA welding, limiting maximum heat input primarily serves to:
• What is thermionic emission?
• What is the thermal conductivity of copper?
• The main purpose of using a lower finishing temperature during controlled rolling of steel is to:
• During welding, why can cracking occur despite precautions?
• Melting temperature of titanium?
• What is the percentage of carbon in the peritectic phase?
• Grain size refinement is the strengthening mechanism that increases both strength and toughness.
• The cracking of aluminum is primarily due to which phenomenon?
• What happens if an Al alloy that has more than 3% Mg and it is exposed to temps between 120 C and 205 C?
• Ionization potential is defined as what?
• Lead can be fusion welded with no shielding gas.
• The oxide state can influence weld porosity; which statement is most accurate?
• Calculate the ideal critical diameter (hardenability) for a steel with 0.2%C, 0.25%Si, 1.0%Mn, 0.5%Cr, 0.5%Mo, 1.0%Ni (assume an initial grain size of ASTM 8). Use section 2.5.3 and 2.5.4 as a reference.
• Carbon steel is easily welded by all resistance welding methods. Which statement is correct?
• The rate of applied strain increases so does the probability of cracking. Which option best reflects this statement?
• Between aluminum and carbon steel, which has higher thermal conductivity?
• If the carbon content increases while keeping the cooling rate the same, what happens to martensite hardness?
• If wormholes are to be avoided, which filler alloy is preferred?
• Conduction in solids can occur via which mechanisms?
• Which of the following is NOT listed as a crystal structure?
• What is the surface oxide associated with lithium-bearing aluminum alloys?
• Which statement best describes ionization potential in a general sense?
• What temperature should not be exceeded when performing thermal stress relief on a welded quenched and tempered steel?
• Preheating reduces the risk of hydrogen cracking in structural steels by which mechanism?
• Transforming the aluminum oxide to lithium oxide or spinel can affect coherency with the substrate. What is the likely outcome?
• Shielding required for titanium?
• Secondary hardening during tempering is due to the presence of which?
• Ozone is generated most during which welding process when using Mg-free filler alloys 443 or AA-1100?
• How is cracking related to mechanical forces in weld metal?
• What is the minimum cast for a 6.8 kg spool?
• Compared to pure tungsten, a 2% thoriated tungsten electrode operates at a ______ temperature.
• The thermal conductivity of aluminum is approximately how many times that of steel?
• A True stable form of carbon in iron is ____
• A weld metal has a strength of 500 MPa after a post-weld relief of two hours. If the relief time is extended to four hours, is it likely the weld would still exceed a minimum strength of 480 MPa?
• Cementite has the chemical formula
• Why does magnesium have a profound influence on the oxide found on aluminum?
• What is the amount of carbon in Ferrite region?
• At what magnesium concentration does the oxide transform to MgO or MgAl2O4 occur?
• What two conditions must be present simultaneously for a weld crack to initiate?
• From 910 C to 1390 C, iron has which crystal structure?
• Which of the following is a primary factor contributing to hydrogen cracking in welds?
• Gold at room temperature is generally stable and does not corrode.
• Ore of aluminum?
• Hardenability of steel is affected by:
• Most fine grain steels retain their fine grains up to which temperature, above which they behave as coarse grain steel?
• Coherency between oxide and substrate after Li oxide formation may change.
• Cracking occurs when the material's resistance to cracking is exceeded by mechanical forces.
• What is the melting temperature of copper (Cu)?
• The coefficient of thermal expansion for aluminum is about how many times that of steel?
• Which temperature marks the limit beyond which fine grain steels no longer retain their fine grains?
• Degree of protection required while welding will depend on reactivity of metals, i.e., rate of oxidation and the stability of oxide.
• Delta ferrite exists up to about 1493 C with ~0.1 wt% carbon.
• The major factors affecting hydrogen cracking are:
• Valence is defined as the bonding capacity of an atom, usually equal to the number of unpaired electrons required to complete the outermost shell.
• Which statement best describes interstitial solid solutions in the iron lattice?
• Eutectic is formed at ________ wt of Carbon
• Would you expect a 1%Cr, 1%Mo, 0.35%V steel to be sensitive to stress relief cracking?
• When slag becomes fluid and ions are mobile, electrical resistance does what?
• Using Figure 2.34, estimate the fastest rate a weld could cool without the HAZ becoming harder than 350 HV for a steel with 0.2%C, 0.18%Si, 0.2%Mn, 0.35%Cr.
• One method to structures to withstand strain is to increase their cross-sectional area normal to the strain direction. Which statement best describes this?
• When steel is heated into the austenite region, carbon and most other elements dissolve to form a single phase. True or False?
• Which of the following represents the eutectic carbon content?
• Fine grain steels are used when ____
• Grain growth tends to minimize which energy term?
• What is the theoretical strength of the pure iron?
• At what % of carbon and temperature does eutectoid form?
• What is the work function of a metal?
• Which statement correctly identifies the use of copper and aluminum in electrical systems?
• Which statement is NOT a property of aluminum?
• Acicular ferrite in weld metal forms by which mechanism?
• Aluminum's oxide layer is protective.
• Melting temperature of aluminum?
• Electrical conductivity supports which welding processes?
• Rate of oxidation increases with temperature.
• Which of the following is NOT listed as a problem with 1XXX filler alloys?
• What is the thickness of the oxide on the surface of aluminum?
• Which alloy has the highest welded strength?
• Which factor is most associated with ozone generation in welding according to the material?
• Eutectoid occurs in __________ state
• How are stresses generated in welding?
• Two ores of iron?
• Which wire has the greatest deoxidizing power?
• Stability of oxide decreases with increase in temp.
• Which region of heat treatment causes dissolution of carbon and most alloying elements into a single phase?
• Metal which ionizes easily is which element?
• The stress at which slip occurs is much __________ than the theoretical stress.
• Which oxide phases form on an aluminum surface when magnesium is present?
• In metals, electrical and thermal conductivity are described as which relationship?
• What is the resulting structure of a 0.6% carbon steel slowly cooled from 900°C to room temperature?
• Ferrite is also known as
• What happens if the cast is too great when setting up the feeder spool?
• Which metal has a thermal conductivity of about 222 W/m·°C?
• What is the reinforcement angle in welding terminology?
• Thermal conductivity of carbon steel?
• The Ellingham diagram is used to compare the feasibility of oxide reductions by different agents at various temperatures.
• The eutectoid transformation produces a two-phase mixture of ferrite and cementite.
• What is responsible for aluminum's excellent corrosion resistance?
• What measure do manufacturers take to reduce friction resistance for filler wires in GMAW?
• Hardness of cementite is
• Name two ways in which preheating may reduce the risk of hydrogen cracking in structural steels.
• Ferrite cannot be considered as __________
• The outermost shell of an atom can accommodate up to how many electrons?
• To avoid stress corrosion cracking, the filler alloy used for elevated temp application is AA-5554, which has 3% max Mg.
• What happens to the carbon trapped in the tetragonal structure when martensite is tempered?
• In welded joints, which region tends to record the lowest Charpy impact values?
• Dislocations in metals may be locked by which of the following, requiring higher stresses before they move?
• Which filler wire is used for GMAW when wire feeding is an issue?
• Which statement best describes wormhole defects in 1XXX alloys?
• Magnetite formula?
• Which element reacts with MgO to form oxides on the aluminum surface?
• Iron will ______ when heated above 910 C.
• Steels form the largest group of commercially important alloys because of the:
• Pearlite is made of which two phases?
• Do interstitial atoms such as hydrogen, carbon or nitrogen cause cracking, embrittlement and other problems?
• Which shielding combination is used for steel?
• The hardness of martensite depends mainly on which factor?
• What is the ionization potential of potassium?
• Which statement best describes interstitial solutions?
• If two metals forming a substitutional solution have similar atomic size and the same crystal structure, which statement is true about the range of compositions that can form?
• During the peritectic reaction, the delta ferrite and liquid transform on cooling into which single phase?
• Composition of the alloy with the lowest melting point is called
• What is the %wt and temp for delta ferrite
• In a weld, where are Charpy impact values usually lowest?
• Which two metals are commonly used as electrical conductors?
• If two metals exhibit complete solid solubility over the entire range of composition, then ...
• Which materials are added to tungsten electrodes to promote thermionic emission?
• A faster growth of cementite plates results in which pearlite outcome?
• If two metals don't exhibit complete solid solubility over the entire range of composition, then ...
• When might it be appropriate to specify basic fluxes for SAW?
• A porous lithium oxide/spinel scale may trap which of the following?
• What is the work function value for thoria?
• In filler wire specification, what does 'cast' refer to?
• Shielding required for lead?
• Secondary hardening during tempering results from:
• In face-centered cubic iron, carbon solubility is higher.
• Hematite formula?
• Martensite formation upon rapid quenching is primarily due to diffusion being:
• An ion is defined as what?
• Eutectic occurs in ________ state
• In body-centered cubic iron, carbon solubility is lower.
• One of the main reasons for limiting the maximum heat input when welding HSLA steels is to:
• Peritectic phase is used to explain which welding phenomenon?
• Why is less ozone generated during AC GTA welding with Mg-free alloys?
• Which statement about nitrogen and aluminum shielding is true?
• A porous Li oxide scale reduces protective capability.
• Dislocations locking results in higher stresses required to move dislocations.
• The oxide transformation from Al oxide to Li oxide/spinel can affect the oxide's adhesion to the metal.
• Pearlite is made of
• Why is oxide thickness on an Mg–Al alloy surface thicker than on a Mg-free alloy for the same thermal and mechanical history?
• What effect does the addition of silicon have on aluminum?
• Which statement accurately reflects the crystal structures mentioned?
• What is the max solubility of carbon in FCC iron by weight?
• Which statement describes the peritectic reaction in steel?
• Which welding parameter has the largest effect on the transfer of elements from an active flux?
• Inert gases have much ______ ionization potential than metals. Which term completes the sentence?