20 Base Metals, Prep & Heat Practice Questions & Answers

1. 1. New hot-rolled plate arrives with mill scale on the surface and a film of cutting oil left from shearing. If the joint is welded without cleaning, what is the most likely direct result in the weld metal?

   • A.Undercut, because the oil film raises the arc voltage along both toes of the finished bead
   • B.Arc strikes, because loose scale forces the welder to restrike the electrode several times
   • C.Porosity, because the oil and scale break down in the arc and release gas into the molten pool✓ Answer
   • D.Excessive convexity, because the mill scale raises the melting temperature of the plate surface layer

   Hydrocarbons, moisture and oxides decompose in the heat of the arc, and the gas they release is trapped as the pool solidifies, so porosity is the discontinuity most often traced to unclean base metal. The same hydrocarbons and moisture also add diffusible hydrogen, which is why underbead cracking follows dirty joints as well. Mill scale does not change the melting temperature of the steel underneath it.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry Welders (base metal cleaning before welding)Report a problem with this question

2. 2. A structural detail must be welded on a galvanized steel member. What does standard practice require before the arc is struck, and why?

   • A.Leave the zinc in place and weld colder, because the coating melts away first and then reflows to protect the finished weld
   • B.Leave the zinc in place and weld hotter, because a slower travel speed burns the coating out of the joint ahead of the arc
   • C.Remove the zinc coating back several inches around the joint, because zinc vapor causes metal fume fever and gases the weld pool✓ Answer
   • D.Remove the zinc coating only from the root face, because zinc trapped under the cap has no effect on the completed weld

   Zinc boils far below the melting point of steel, so any coating left in the weld area vaporizes into the breathing zone and into the molten pool. The zinc oxide fume produces metal fume fever, a flu-like reaction that appears hours after exposure, and the trapped vapor produces porosity, so the coating is ground back from the weld area before welding.

   Source: ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes (welding on coated base metals)Report a problem with this question

3. 3. A shop welds both carbon steel and austenitic stainless steel. Why must the wire brush used on stainless steel joints be a stainless-bristle brush kept only for stainless?

   • A.A carbon steel brush leaves carbon in the surface that raises the carbon content of the deposited weld metal above spec
   • B.A carbon steel brush builds a static charge on stainless that pulls shielding gas away from the molten weld pool
   • C.A carbon steel brush embeds iron particles in the stainless surface, and those particles rust and start corrosion✓ Answer
   • D.A carbon steel brush is too soft to lift the chromium oxide film, so the joint stays coated and will not fuse at all

   Carbon steel bristles transfer free iron into the passive chromium oxide surface of the stainless. That embedded iron rusts and destroys the corrosion resistance the alloy was chosen for, so brushes are made of stainless bristles and segregated by material to prevent cross-contamination.

   Source: AWS D1.6, Structural Welding Code - Stainless Steel (cleaning of stainless base metal)Report a problem with this question

4. 4. Why must the oxide layer be removed from aluminum immediately before welding, and what tool is appropriate for that job?

   • A.The oxide traps heat at the surface, so it is removed by wiping the joint with water just before welding starts
   • B.The oxide is magnetic and deflects the arc, so it is removed with a carbon steel brush and a chipping hammer
   • C.The oxide melts far above the aluminum itself, so it is brushed off with a clean stainless brush kept for aluminum✓ Answer
   • D.The oxide melts far below the aluminum itself, so it is burned out of the joint with a short torch preheat before welding

   Aluminum oxide melts at a temperature several times higher than the aluminum beneath it, so the film stays solid while the base metal turns to liquid and it becomes trapped in the joint as an inclusion. It is removed mechanically with a clean stainless brush reserved for aluminum, or chemically, and welded soon after because the film reforms quickly.

   Source: AWS D1.2, Structural Welding Code - Aluminum (oxide removal before welding)Report a problem with this question

5. 5. A single-V groove is prepared on 3/8 in. plate. The welding procedure calls for a 3/32 in. root face. Measured through the thickness of the plate, how much of the prepared edge is groove face?

   • A.3/16 in., because the groove face is always half of the plate thickness on a single-V
   • B.3/32 in., because the groove face and the root face are always cut to the same height
   • C.15/32 in., because the groove face equals the plate thickness plus the root face height
   • D.9/32 in., because the root face and the groove face together equal the plate thickness✓ Answer

   The root face is the flat, unbeveled land at the bottom of the groove face, and the two together span the full thickness of the member. Converting to thirty-seconds, 3/8 in. is 12/32 in. and the 3/32 in. root face leaves 9/32 in. of groove face.

   Source: AWS A3.0, Standard Welding Terms and Definitions (root face and groove face)Report a problem with this question

6. 6. A drawing calls for an open-root V-groove butt joint in plate with a 60 degree groove angle, and both members are prepared alike. What bevel angle is cut on each plate edge, and how is that angle measured?

   • A.30 degrees on each member, measured from a line perpendicular to the surface of the plate✓ Answer
   • B.30 degrees on each member, measured from the plate face up to the prepared edge
   • C.15 degrees on each member, measured from the root face out to the plate edge
   • D.60 degrees on each member, measured from a plane perpendicular to the plate surface

   The groove angle is the total included angle of the groove between the two members, while the bevel angle is the angle of one prepared member measured from a line perpendicular to its surface. Two equal 30 degree bevel angles therefore produce the 60 degree groove angle the drawing specifies.

   Source: AWS A3.0, Standard Welding Terms and Definitions (bevel angle and groove angle)Report a problem with this question

7. 7. On a double-sided groove weld the first side is welded and the joint is then back gouged before the second side is welded. What is the purpose of back gouging?

   • A.To harden the root of the first side so the second side can be welded with far less heat input
   • B.To preheat the back of the joint locally so the second side needs no further temperature control
   • C.To widen the groove angle on the second side so a larger diameter electrode can be used there
   • D.To cut out the root of the first side down to sound metal so the second side fuses completely✓ Answer

   The root of the first side commonly contains incomplete fusion, slag or an unsound bead that would remain buried in the finished joint. Back gouging removes that material down to sound metal so the second-side weld fuses into clean base and weld metal and complete joint penetration is achieved.

   Source: AWS A3.0, Standard Welding Terms and Definitions (back gouging)Report a problem with this question

8. 8. Two pipe sections are fitted for a butt weld and the welder needs to check whether the inside surfaces line up at the joint before tacking. Which measuring tool is made for that check?

   • A.A steel protractor, which reads the internal offset by measuring the bevel angle of each end
   • B.A combination square with its centering head, which reads the internal offset between two pipe ends
   • C.A torpedo level, whose bubble vial reads the offset between the two pipe bores at the joint
   • D.A Hi-Lo gauge, which reads internal misalignment between the two pipe ends and the root opening✓ Answer

   The Hi-Lo gauge is built specifically to reach into the bore and read the high-low condition, the internal mismatch between two pipe ends, and most versions also read root opening and wall mismatch. A centering head locates the center of round stock, a level reads level and plumb, and a protractor reads angles, so none of those can measure internal offset.

   Source: NCCER Welding curriculum, Joint Fit-Up and Alignment (Hi-Lo gauge)Report a problem with this question

9. 9. A fitter tacks strongbacks across a plate seam to hold the members in alignment while the joint is welded out. How should those strongbacks be attached and dealt with afterward?

   • A.Tack them on one side only, then break them off and grind the attachment area flush and inspect it✓ Answer
   • B.Tack them with a single arc strike each, so no filler metal is added to the plate surface
   • C.Tack them on all four sides, then cut them off close to the plate and leave the stubs in place
   • D.Tack them inside the groove itself, so the root pass melts the tacks out as the joint is welded

   A strongback tacked on one side only can be broken off cleanly in the direction opposite the tack without tearing the plate surface. The attachment area is then ground flush and inspected for gouges and arc strikes, because those act as notches and become crack starters in service.

   Source: NCCER Welding curriculum, Joint Fit-Up and Alignment (strongbacks and tack welds)Report a problem with this question

10. 10. A long seam is being welded on thin plate and the fabricator specifies back-step welding to hold distortion down. What does back-step welding mean?

    • A.The seam is welded in one pass from the center out, then the plate is turned and welded the same way
    • B.Short weld increments are deposited in the direction opposite to the overall progression of the seam✓ Answer
    • C.Short weld increments are deposited from both ends of the seam toward the middle in one continuous pass
    • D.The seam is welded downhill so the puddle cools faster and the shrinkage force is reduced

    In back-step welding the joint advances overall in one direction, but each short increment is deposited in the opposite direction. Spreading the heat this way keeps shrinkage from accumulating continuously along the seam, so longitudinal shrinkage and bowing are reduced.

    Source: AWS Welding Handbook, distortion control (back-step sequence)Report a problem with this question

11. 11. A single-V groove weld in plate pulls the two plates up toward each other as the weld cools, leaving them out of plane. Which control measure directly counters this angular distortion?

    • A.Grind the finished cap flush with the plate so the shrinkage stress is removed from the joint
    • B.Preset the members tilted apart so weld shrinkage pulls them into the required alignment✓ Answer
    • C.Increase the groove angle so the extra weld metal deposited resists the shrinkage forces
    • D.Weld the entire joint in one heavy pass so the plate never has a chance to cool and shrink

    A single-V groove holds more weld metal near the face than at the root, so the face shrinks more and the members rotate toward each other. Presetting tilts the members the opposite way by a known amount before welding, letting the predictable shrinkage pull them into the required position. Adding weld metal or a wider groove increases the shrinkage rather than resisting it.

    Source: AWS Welding Handbook, distortion control (presetting and prebending)Report a problem with this question

12. 12. Two plain carbon steel plates of the same thickness are to be welded, one a low carbon steel and the other a high carbon steel. What does the higher carbon content predict about welding the second plate?

    • A.The high carbon steel conducts heat away faster and therefore needs no preheat at all
    • B.The high carbon steel hardens more in the heat-affected zone and is more likely to crack✓ Answer
    • C.The high carbon steel melts at a much lower temperature and burns through more easily
    • D.The high carbon steel stays more ductile in the heat-affected zone and is less likely to crack

    Carbon is the element that makes steel hardenable, so as carbon content rises the heat-affected zone transforms to harder, more brittle martensite when the weld cools quickly. That hard, low-ductility structure combined with residual stress and diffusible hydrogen is what produces cracking, which is why higher carbon steels call for preheat, controlled cooling and low-hydrogen practice.

    Source: AWS D1.1, Structural Welding Code - Steel (carbon content and hydrogen-assisted cracking)Report a problem with this question

13. 13. A welder checks an unmarked stainless plate with a magnet and it is not attracted. Which stainless family does that point to, and what else is true of it?

    • A.Ferritic chromium stainless, the 400 series group, which is not hardenable by heat treatment
    • B.Any stainless at all, because chromium content above eleven percent removes magnetism entirely
    • C.Austenitic chromium-nickel stainless, the 300 series group, which is not hardenable by heat treatment✓ Answer
    • D.Martensitic stainless, a higher carbon group, which is hardened and tempered like carbon steel

    Grain structure, not chromium alone, decides magnetic response: the austenitic chromium-nickel grades are essentially nonmagnetic, while the ferritic and martensitic chromium grades are magnetic. Austenitic stainless cannot be hardened by heat treatment, only by cold work, which is why the magnet test is a useful first screen on unmarked stock.

    Source: AWS D1.6, Structural Welding Code - Stainless Steel (austenitic, ferritic and martensitic families)Report a problem with this question

14. 14. Cast iron is considered a difficult weldment. What property of cast iron is the main reason, and what does that property cause during welding?

    • A.Its very high carbon content makes it brittle, so rapid cooling cracks the weld and the casting✓ Answer
    • B.Its low melting point makes it very fluid, so the puddle runs out of the joint before it solidifies
    • C.Its very low carbon content makes it soft, so the weld sags and undercuts along the joint edges
    • D.Its high nickel content makes it nonmagnetic, so the arc wanders and will not stay in the joint

    Cast iron carries roughly two to four percent carbon, far above any steel, and that carbon leaves it brittle with almost no ability to yield. When the weld and heat-affected zone cool quickly they form hard, brittle structures while shrinkage stress builds, and the casting cracks, which is why slow preheat, low heat input and slow controlled cooling are used.

    Source: AWS D11.2, Guide for Welding Iron CastingsReport a problem with this question

15. 15. A welding instructor asks which item in a list is a physical characteristic of a metal rather than a mechanical property. Which one is the physical characteristic?

    • A.Tensile strength, the pulling stress the metal withstands before it finally breaks
    • B.Ductility, the amount the metal stretches out before it separates under a load
    • C.Hardness, the resistance the metal surface offers to being indented or scratched
    • D.Thermal conductivity, the rate at which the metal carries heat away from the arc✓ Answer

    Physical characteristics are what a metal is without any load applied, such as melting point, density, electrical and thermal conductivity and coefficient of thermal expansion. Mechanical properties describe how the metal responds to an applied force, which covers tensile strength, ductility, hardness and toughness, so thermal conductivity is the only physical characteristic listed.

    Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry Welders (physical characteristics and mechanical properties of metals)Report a problem with this question

16. 16. An unmarked steel bar is touched to a grinding wheel and throws a long stream of straight sparks with very few bursts. What does that spark pattern indicate, and what should the welder do with the result?

    • A.A relatively low carbon content, but the bar still needs positive identification before a procedure is chosen✓ Answer
    • B.A low alloy content, so the bar can be joined with any filler metal that happens to be in the shop
    • C.A relatively high carbon content, so the bar can be welded straight away with no preheat at all
    • D.A high chromium content, so the bar should be treated as austenitic stainless and welded as such

    In a spark test the number and shape of the bursts track carbon content: low carbon steel gives long, straight, sparsely bursting streams, while higher carbon steel gives many repeated forked bursts. The test is only an indicator, so an unidentified metal is still treated as unknown until a mill test report or an instrument analysis confirms it and a procedure is selected.

    Source: NCCER Welding curriculum, Physical Characteristics and Mechanical Properties of Metals (spark test for metal identification)Report a problem with this question

17. 17. Before starting a job a welder is handed a welding procedure specification (WPS) and the procedure qualification record (PQR) that supports it. What is the difference between the two documents?

    • A.The WPS gives the welder the variables to work to; the PQR records the test results proving them✓ Answer
    • B.The WPS lists the welder's own qualified positions; the PQR lists the shop's approved base metals
    • C.The WPS records the test results; the PQR gives the welder the variables to work to on the job
    • D.The WPS is written by the welder after the job; the PQR is written by the inspector before it

    The WPS is the working instruction: base metal and thickness range, joint design and backing, filler metal, position, electrical characteristics, cleaning and the preheat and interpass limits the welder must hold. The PQR is the historical record of the actual values used on a test coupon and the mechanical test results that proved the procedure sound, so it supports the WPS rather than being read at the joint.

    Source: AWS B2.1, Specification for Welding Procedure and Performance QualificationReport a problem with this question

18. 18. A thick, highly restrained carbon steel joint is to be welded in a cold shop. Why does the procedure call for preheat before the root pass?

    • A.It slows the cooling rate, so the heat-affected zone stays softer and hydrogen can escape✓ Answer
    • B.It burns the carbon out of the joint surface so the steel behaves like a low carbon steel
    • C.It speeds the cooling rate, so the heat-affected zone freezes before any hydrogen can enter it
    • D.It raises the base metal above its melting point so the root pass needs less filler metal

    Thickness, restraint and low ambient temperature all pull heat out of the joint faster, and a fast quench in a hardenable steel forms brittle martensite in the heat-affected zone. Preheat slows that cooling so the microstructure stays softer, gives diffusible hydrogen time to escape, drives off surface moisture and lowers the thermal gradient that drives shrinkage stress.

    Source: AWS D1.1, Structural Welding Code - Steel (purpose of preheat)Report a problem with this question

19. 19. A welding procedure specification lists a 50°F minimum preheat and a 500°F maximum interpass temperature. The welder keeps running passes and the plate reaches 650°F. What is the correct action and the reason?

    • A.Stop and reheat the plate to 500°F, because the interpass value listed is a minimum to be maintained
    • B.Stop and let the plate cool below 500°F in still air, because too much heat coarsens the grain and lowers toughness✓ Answer
    • C.Quench the plate with water down to 500°F, because that returns it at once to the range the procedure requires
    • D.Keep welding above 500°F, because a hotter plate always deposits a sounder and more ductile weld

    The maximum interpass temperature stated on the procedure is a limit, not a target: running above it coarsens the grain, lowers notch toughness and softens quenched and tempered steels. The plate is allowed to cool naturally until it is back under the stated maximum, and it is never quenched with water, because a fast quench hardens the heat-affected zone and can crack the joint.

    Source: AWS D1.1, Structural Welding Code - Steel (interpass temperature control)Report a problem with this question

20. 20. Immediately after welding a highly restrained carbon steel joint, the procedure calls for the weldment to be held at an elevated temperature for a set time before it is allowed to cool. What does this postheat accomplish?

    • A.It hardens the weld deposit quickly, which raises the tensile strength of the finished joint
    • B.It burns off the slag left on the cap, which removes the need to clean between the final passes
    • C.It gives diffusible hydrogen time to escape, which prevents delayed cracking hours after welding✓ Answer
    • D.It pushes residual hydrogen deep into the weld, which seals it away from the heat-affected zone entirely

    Hydrogen-assisted cracking needs three things at once: diffusible hydrogen, a crack-susceptible hard microstructure and tensile stress, and it can appear a day or more after the arc is off. Holding the joint hot right after welding keeps hydrogen mobile so it diffuses out of the steel before the weldment cools into the temperature range where that cracking occurs.

    Source: AWS Welding Handbook, hydrogen-assisted cracking and post-weld hydrogen bakeoutReport a problem with this question

Practice questions based on the AWS SENSE Level I (Entry Welder) written modules, ANSI Z49.1 safety practice, and AWS A2.4 welding symbols. This bank covers the KNOWLEDGE half of entry-level welding only — the workmanship and welder performance qualification tests are hands-on and cannot be practised here, and this is not preparation for the separate, performance-based AWS Certified Welder credential. AWS, SENSE, and NCCER are marks of their respective organizations; this site is not affiliated with or endorsed by them. Work from your program's current materials, and follow the welding procedure and drawings on your own job rather than any number you remember. About AWS SENSE →