I85PREP
⌘ K
ITI/NCVT Welder (Fab & Fit) (AITT Theory) study materials
ITI/NCVT Welder (Fab & Fit) (AITT Theory) study resources

ITI/NCVT Welder (Fab & Fit) (AITT Theory) practice questions

One question at a time. Build your ITI/NCVT Welder (Fab & Fit) (AITT Theory) understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Safety, Health and Environment in Welding Workshop

In an oxy-acetylene welding set, which colour identifies the acetylene hose according to common Indian workshop practice?

  1. Green
  2. Black
  3. Red Correct answer.
  4. Blue

Explanation

Acetylene hoses are conventionally red so that the fuel-gas line can never be confused with the oxygen line. Oxygen hoses are black or blue-green depending on the standard used. Correct hose identification prevents a fuel gas being connected to an oxygen fitting, which is a serious fire hazard.

Question 2Safety, Health and Environment in Welding Workshop

A welder notices the flashback arrestor is missing from the acetylene regulator outlet. What is the correct action before starting work?

  1. Increase acetylene pressure to overcome the missing device
  2. Start welding at low pressure and report it later
  3. Use only the oxygen side arrestor and continue
  4. Fit the arrestor or replace the regulator before welding Correct answer.

Explanation

A flashback arrestor stops a flame from travelling back into the cylinder and causing an explosion. Welding must not begin until the device is fitted on the fuel-gas line. Raising pressure or relying on the oxygen-side device alone gives no protection to the acetylene cylinder.

Question 3Safety, Health and Environment in Welding Workshop

Which type of fire extinguisher is suitable for a fire involving the acetylene cylinder and its fittings?

  1. Foam (class B)
  2. Water (class A)
  3. Soda-acid
  4. Dry powder (class C/D suitable) Correct answer.

Explanation

Gas fires involving acetylene require dry powder extinguishers, and the cylinder should also be cooled with water spray from a safe distance. Water jets, foam and soda-acid units are not suitable for gas fires and can spread burning material. The priority is to shut off the gas if safe and raise the alarm.

Question 4Safety, Health and Environment in Welding Workshop

What is the main purpose of local exhaust ventilation in a welding bay?

  1. To increase the arc voltage for better penetration
  2. To capture fume at source before it reaches the welder's breathing zone Correct answer.
  3. To cool the welded joint quickly
  4. To supply extra oxygen to the flame

Explanation

Local exhaust ventilation extracts welding fume close to the arc, before it can be inhaled. This reduces exposure to metal fume and gases such as ozone and nitrogen oxides. Cooling the joint, changing voltage and feeding oxygen are not functions of extraction equipment.

Question 5Safety, Health and Environment in Welding Workshop

Before arc welding on a steel structure, the welder must connect the work-return (earth) cable. Where should the clamp be attached?

  1. To the workpiece itself or to a clean metal part directly connected to it Correct answer.
  2. To the welding table leg whichever table is nearest
  3. To the electrode holder body
  4. To any painted surface of the structure

Explanation

The work-return clamp must be fixed to the workpiece or to metal firmly connected to it, on a clean surface for good electrical contact. This keeps the welding current path short and prevents stray current flowing through slings, bearings or earth conductors. A poor or remote connection creates arcing and shock risk.

Question 6Safety, Health and Environment in Welding Workshop

Which personal protective equipment is essential when chipping slag from a completed weld?

  1. Ear plugs only
  2. Leather gloves and impact-resistant eye protection Correct answer.
  3. A cotton cap and open sandals
  4. A dust mask only

Explanation

Chipping slag throws hot, sharp fragments at high speed, so leather gloves and impact-rated goggles or a face shield are required. Ordinary spectacles or a dust mask give no protection against flying scale. Eye injuries from slag are among the most common welding-shop accidents.

Question 7Safety, Health and Environment in Welding Workshop

A welder is working inside a confined tank. Which control measure is mandatory before entry?

  1. Sealing the tank to keep out draughts
  2. Welding at maximum current to finish quickly
  3. Forced ventilation, gas testing and an attendant outside Correct answer.
  4. A second welder inside the tank for company

Explanation

Confined-space welding requires gas testing for oxygen and flammable or toxic gases, forced ventilation and a trained attendant stationed outside with rescue arrangements. These controls prevent asphyxiation, fume build-up and explosion. Working faster or sealing the space increases the danger.

Question 8Safety, Health and Environment in Welding Workshop

Why must an acetylene cylinder never be laid on its side for use?

  1. The cylinder paint would be damaged
  2. The hose would be too short to reach the torch
  3. It would make the cylinder too heavy to move
  4. Liquid acetone may enter the regulator and cause erratic flame or flashback Correct answer.

Explanation

Acetylene is dissolved in acetone held in a porous mass, and lying the cylinder down lets liquid acetone reach the valve and regulator. This causes a violent flame, solvent damage to the regulator and possible flashback. Cylinders must be used and stored upright.

Question 9Safety, Health and Environment in Welding Workshop

During MMA welding, the welder feels a tingling sensation through the gloves. What is the most likely cause and the correct response?

  1. Too high a welding current; reduce the setting and continue
  2. Faulty insulation or damp gloves; stop and have the equipment checked Correct answer.
  3. Normal arc characteristic; continue welding
  4. Too low an open-circuit voltage; increase the setting

Explanation

Tingling indicates leakage current reaching the body, usually from damaged cable insulation, a faulty holder or damp gloves. Work must stop immediately and the equipment inspected by a competent person. Continuing to weld risks a fatal electric shock.

Question 10Safety, Health and Environment in Welding Workshop

What is the correct first-aid action for a small hot-metal burn on the forearm?

  1. Apply grease or oil to the burn
  2. Cool with clean running water and cover with a sterile non-stick dressing Correct answer.
  3. Rub the area with a cloth to remove metal particles
  4. Burst any blister to release the fluid

Explanation

Minor burns should be cooled with clean running water for about ten to twenty minutes and then covered with a sterile non-stick dressing. Grease, oils and traditional remedies trap heat and invite infection. Blisters must never be deliberately burst.

Question 11Safety, Health and Environment in Welding Workshop

A welding transformer is rated at 400 V primary. Which precaution protects the operator from the primary side?

  1. Keeping the terminal cover closed and interlocked Correct answer.
  2. Standing on a wooden plank while welding
  3. Earthing the electrode holder
  4. Wearing tinted goggles

Explanation

The primary side carries dangerous mains voltage, so terminal covers, interlocks and enclosure panels must be kept closed and intact. Only authorised electricians may open the primary enclosure. Earthing the holder, standing on wood or eye protection address the secondary side, not primary contact.

Question 12Safety, Health and Environment in Welding Workshop

Which gas mixture is produced when welding or cutting in a confined space without ventilation and can cause asphyxiation by displacing oxygen?

  1. Argon or carbon dioxide shielding gas leaking into the space Correct answer.
  2. Nitrogen from the fuel hose
  3. Compressed air from the torch
  4. Carbon dioxide from the shielding gas

Explanation

Inert shielding gases such as argon and carbon dioxide are heavier than air and collect in low areas, displacing oxygen. In a confined space this can cause rapid asphyxiation without warning. Ventilation and continuous oxygen monitoring are essential.

Question 13Safety, Health and Environment in Welding Workshop

How should gas cylinders be stored in a welding workshop?

  1. Near the welding bay for quick access
  2. Stacked on top of each other to save space
  3. Upright, secured against falling, with oxygen and fuel gas separated Correct answer.
  4. Lying horizontally in a locked store

Explanation

Cylinders must be stored upright and chained or otherwise secured so they cannot fall and shear the valve. Oxygen and fuel-gas cylinders should be separated by a fire-resistant barrier or distance, and kept away from ignition sources. This limits the risk of a cylinder rocket or fire.

Question 14Safety, Health and Environment in Welding Workshop

A welder is grinding a weld with a portable angle grinder. Which practice reduces the risk of the wheel bursting?

  1. Running the wheel at any speed the operator prefers
  2. Using a worn wheel from a larger machine
  3. Using a wheel rated above the grinder's marked speed Correct answer.
  4. Removing the wheel guard to reach the corner

Explanation

Grinding wheels must be rated at or above the maximum speed marked on the machine, because overspeeding is a common cause of wheel burst. The guard must stay fitted to contain fragments. Mixing wheels from other machines or removing guards creates serious injury risk.

Question 15Safety, Health and Environment in Welding Workshop

Which statement correctly describes the purpose of a welding screen or booth in a fabrication shop?

  1. It protects nearby workers from arc radiation and spatter Correct answer.
  2. It increases the welding current
  3. It replaces the need for a welding helmet
  4. It removes the need for fume extraction

Explanation

Screens and booths shield other people from ultraviolet and visible arc radiation, which can cause arc eye, and contain spatter. They do not replace the welder's own helmet or fume extraction. Screens are a workplace control, not a process control.

Question 16Safety, Health and Environment in Welding Workshop

A welder is using a petrol-driven engine welder indoors. Which hazard is most significant and how should it be controlled?

  1. Vibration; use gloves only
  2. Fuel spillage; mop it up after welding
  3. Carbon monoxide poisoning; run it outdoors or duct the exhaust outside Correct answer.
  4. Noise; wear ear plugs only

Explanation

Petrol engines produce carbon monoxide, an odourless gas that can rapidly reach lethal concentrations indoors. The engine must run outdoors or its exhaust must be ducted to open air, with ventilation and gas monitoring. Noise and vibration controls are useful but do not address the fatal hazard.

Question 17Safety, Health and Environment in Welding Workshop

In a workshop, a welder must work on a job at height using a mobile scaffold. Which combination of controls is most appropriate?

  1. Ask a colleague to hold the ladder while welding from it
  2. Stand on an upturned bucket beside the scaffold
  3. Use a properly erected scaffold with guardrails, toe boards and a fall-arrest harness where required Correct answer.
  4. Stand on the top guardrail to reach the joint

Explanation

Work at height requires a properly erected scaffold with guardrails, toe boards and stable footing, plus a fall-arrest system where the risk assessment demands it. Improvised platforms and climbing on guardrails are common causes of fatal falls. Welding from a ladder while being held is also unsafe.

Question 18Safety, Health and Environment in Welding Workshop

A welder finds a small pinhole leak at the acetylene regulator gland and detects a gas smell. What is the correct immediate sequence of actions?

  1. Ignore the smell because acetylene is odourless
  2. Tighten the gland nut with a spanner while the gas is on
  3. Shut the cylinder valve, ventilate the area, remove ignition sources and report Correct answer.
  4. Spray soap solution on the leak and continue welding

Explanation

A leak must be isolated at the cylinder valve, the area ventilated and all ignition sources removed before reporting it to a responsible person. Acetylene is flammable over a wide range and can ignite from a spark or hot surface. Repairs to regulators must be done by trained personnel with the equipment depressurised.

Question 19Safety, Health and Environment in Welding Workshop

Which welding process generates the greatest risk of exposure to hexavalent chromium fume, requiring extra ventilation and health surveillance?

  1. Manual metal arc welding of stainless steel with basic coated electrodes Correct answer.
  2. Gas tungsten arc welding of aluminium
  3. Brazing of copper pipe
  4. Oxy-acetylene welding of mild steel

Explanation

Welding stainless steel, which contains chromium, produces hexavalent chromium fume that is carcinogenic and requires enhanced extraction and health surveillance. Mild steel, aluminium and copper brazing do not generate the same chromium exposure. Process selection and fume control must follow the risk assessment.

Question 20Safety, Health and Environment in Welding Workshop

What is the primary reason for earthing the welding transformer or inverter enclosure?

  1. To improve arc stability and penetration
  2. To provide a low-resistance path so fault current trips the protective device Correct answer.
  3. To increase the duty cycle of the machine
  4. To reduce the open-circuit voltage to zero

Explanation

Earthing the enclosure ensures that if a live conductor touches the metal case, fault current flows to earth and operates the circuit breaker or fuse quickly. This protects the operator from a fatal shock. Arc stability, open-circuit voltage and duty cycle are unrelated to protective earthing.

Question 21Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

In a fillet weld symbol, the perpendicular leg of the right-angle triangle is placed on which side of the reference line?

  1. Above the tail of the reference line
  2. Centred on the reference line
  3. On the arrow side of the reference line Correct answer.
  4. On the other side of the reference line

Explanation

The fillet weld symbol is a right-angle triangle drawn with the perpendicular leg always on the left of the symbol, and this perpendicular leg is placed on the arrow side of the reference line. The arrow side is the side of the joint to which the arrow points, so the symbol's orientation tells the welder where the weld is deposited.

Question 22Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A welding symbol shows the letter 'S' in the tail and a number in front of a fillet weld symbol. What does the number placed to the left of the fillet symbol specify?

  1. The root gap before welding
  2. The leg length of the fillet weld Correct answer.
  3. The length of the weld in millimetres
  4. The number of passes required

Explanation

On a fillet weld symbol, the dimension written to the left of the triangle gives the leg length (size) of the fillet. The length of the weld, when it is not continuous, is written to the right of the symbol.

Question 23Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

What does a small circle placed at the junction of the reference line and the leader line indicate?

  1. The weld is to be made all around the joint Correct answer.
  2. The weld is a temporary tack weld
  3. The weld is to be made in the shop only
  4. The weld is to be ground flush after welding

Explanation

The circle at the bend between the leader and reference line is the 'weld all around' symbol. It instructs the welder to continue the weld around the entire perimeter of the joint.

Question 24Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

On a welding symbol, a letter 'F' placed in the tail of the reference line most commonly indicates which condition?

  1. The weld is to be made in the shop
  2. The weld requires full penetration
  3. The weld is to be finished flush
  4. The weld is to be made in the field Correct answer.

Explanation

A flag at the junction of the leader and reference line, usually lettered 'F', marks a field weld, meaning the weld is made at the site of final assembly rather than in the workshop. The tail itself is reserved for process, specification or reference notes.

Question 25Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

In a first-angle projection drawing, where is the view from the top of the object placed relative to the front view?

  1. Below the front view Correct answer.
  2. To the right of the front view
  3. Above the front view
  4. To the left of the front view

Explanation

First-angle projection places the object between the observer and the plane of projection, so the top view appears below the front view and the left-side view appears on the right. This is the reverse of third-angle projection.

Question 26Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing dimension reads '50 ±0.5'. What total tolerance is permitted on the dimension?

  1. 1.0 mm Correct answer.
  2. 25 mm
  3. 0.25 mm
  4. 0.5 mm

Explanation

A bilateral tolerance of plus or minus 0.5 mm gives a total permissible variation of 1.0 mm, from 49.5 mm to 50.5 mm. The tolerance band is the difference between the upper and lower limits.

Question 27Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A groove weld symbol has the letter 'V' with the opening of the V facing away from the reference line and placed below the line. On which side of the joint is the weld prepared?

  1. Arrow side
  2. Neither side; it is a backing run
  3. Other side Correct answer.
  4. Both sides equally

Explanation

A weld symbol drawn on the side of the reference line away from the arrow indicates a weld on the other side of the joint. The V opening direction shows the groove preparation faces that side.

Question 28Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing calls for a 'double fillet weld, 6 mm leg, 100 mm long, staggered 50 mm pitch'. Which feature does the pitch dimension describe?

  1. The length of each unwelded gap only
  2. The throat thickness of each increment
  3. The distance between the centres of successive weld increments Correct answer.
  4. The overall length of the joint

Explanation

For intermittent or staggered welds, the pitch is the centre-to-centre distance between successive increments of weld along the joint. It equals the weld length plus the unwelded gap.

Question 29Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

On an engineering drawing, the abbreviation 'CL' with a chain line through a symmetrical part indicates what?

  1. The chamfer length on a shaft
  2. A concealed edge behind the surface
  3. A cutting plane for a section view
  4. The centre line of the part Correct answer.

Explanation

A chain line with the letters CL marks the centre line of a symmetrical feature such as a shaft, hole pattern or bore. It is a reference axis used for locating dimensions and for symmetry.

Question 30Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A weld symbol shows a groove weld with the letter 'U' and the note '2 mm root gap, 60° included angle'. Which fit-up check is most critical before welding?

  1. Checking the welding cable current setting only
  2. Checking the surface finish of the parent plate only
  3. Checking the root gap and the included bevel angle of the preparation Correct answer.
  4. Checking the colour of the primer on the plate

Explanation

For a U-groove or any groove weld, the root gap and included angle control penetration and the shape of the weld pool. The welder must verify these against the drawing or WPS before striking the arc.

Question 31Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing uses a datum feature symbol (a filled triangle with a boxed letter) on a surface. What is the purpose of this symbol?

  1. To show the direction of rolling on the plate
  2. To specify the weld finish contour
  3. To identify the surface from which positional tolerances are measured Correct answer.
  4. To indicate that the surface must be painted

Explanation

The datum feature symbol establishes a datum, a theoretically exact reference plane or axis from which geometric tolerances such as flatness, perpendicularity and position are measured. All related feature control frames refer back to it.

Question 32Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing detail shows a plate dimensioned 200 mm with a 1:5 taper on one edge. What does the taper ratio 1:5 mean?

  1. The weld leg is 5 times the plate thickness
  2. The edge is 5 mm thick for every 1 mm of length
  3. The plate is reduced in length by 5 mm per metre
  4. For every 5 mm along the axis, the edge moves 1 mm sideways Correct answer.

Explanation

A taper ratio of 1:5 means a rise of one unit for every five units measured along the taper axis. It defines the included angle of the tapered edge, which the fitter must mark out accurately.

Question 33Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing shows a weld symbol with a concave contour symbol (a shallow curve) above the fillet triangle. What does this require the welder to do?

  1. Grind the weld completely flush and smooth
  2. Make the weld in the vertical-up position
  3. Produce a flat weld face flush with the plate surface
  4. Produce a slightly concave weld face without excessive convexity Correct answer.

Explanation

The concave finishing symbol tells the welder to shape the fillet face so it is concave, avoiding a convex profile that would create a sharp toe transition. This improves fatigue performance and reduces stress concentration at the toe.

Question 34Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A fabrication drawing specifies a 'root gap 2 mm, root face 1.5 mm' for a single-V butt joint in 10 mm plate. Which fit-up error would most directly cause lack of penetration?

  1. Increasing the root gap to 3 mm
  2. Reducing the root face to 1 mm
  3. Increasing the root face to 4 mm Correct answer.
  4. Increasing the included bevel angle to 70°

Explanation

A root face that is too large leaves a thick unpenetrated land at the joint root, so the arc cannot melt through and lack of penetration results. The specified root face must be maintained during edge preparation and fit-up.

Question 35Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing gives a hole position as 'Ø20 H7'. What does the 'H7' designation specify?

  1. The surface roughness of the bore
  2. The material specification of the part
  3. The tolerance class of the hole, with the lower deviation at zero Correct answer.
  4. The depth of the hole in millimetres

Explanation

In the ISO limits and fits system, 'H' denotes a hole whose fundamental deviation is zero at the lower limit, and '7' is the standard tolerance grade. Together H7 defines the upper and lower limits of the bore diameter.

Question 36Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing shows a weld symbol with the tail containing 'WPS-12' and the reference line carrying a fillet symbol on both sides. What does the double-sided fillet symbol require?

  1. A full penetration butt weld
  2. A fillet weld on both sides of the joint at the location shown Correct answer.
  3. A seal weld only on the far side
  4. A single fillet weld on the arrow side only

Explanation

Fillet symbols placed on both sides of the reference line indicate fillet welds on both the arrow side and the other side of the joint. The tail note refers the welder to the relevant welding procedure specification for details.

Question 37Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing shows a section view with hatching lines running in one direction on one part and at 90° on an adjacent part. What does this convention communicate?

  1. The parts have been heat treated differently
  2. The parts are welded together with a full penetration weld
  3. The section has been taken at two different depths
  4. The two parts are of different materials or are separate components in the assembly Correct answer.

Explanation

Adjacent parts in a section are hatched in opposite or clearly different directions so their boundaries remain visible. This distinguishes separate components or different materials in the assembly.

Question 38Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing uses a 'break line' (a thin irregular line) across a long shaft. What is the purpose of this line?

  1. To show that a portion of the part has been omitted to save drawing space Correct answer.
  2. To mark the position of a welded joint
  3. To show the direction of assembly
  4. To indicate a machined surface finish

Explanation

Break lines indicate that a portion of a long, uniform part has been removed so the view fits on the sheet at a usable scale. Dimensions still refer to the true full length of the part.

Question 39Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A detail drawing shows a weld symbol with a number in parentheses, such as '(4)', placed at the tail. In welding symbol practice, what does a number in parentheses at the tail most commonly represent?

  1. The preheat temperature in hundreds of degrees
  2. The number of passes required for the joint
  3. The number of welders to be assigned
  4. A reference number identifying the welding procedure or specification Correct answer.

Explanation

The tail of the reference line is used for supplementary information such as process references, specifications or drawing reference numbers. A bracketed number there is a reference identifier, not a welding parameter.

Question 40Engineering Drawing, Reading of Weld Symbols and Fit-up Layout

A drawing gives a positional tolerance of 'Ø0.2 M' in a feature control frame for a bolt hole. What does the 'M' modifier change about the acceptance of the part?

  1. It removes the need for a datum reference
  2. It requires the hole to be measured only at its minimum size
  3. It makes the tolerance applicable only to the weld surface
  4. It allows a bonus tolerance as the hole departs from its maximum material condition Correct answer.

Explanation

The maximum material condition modifier allows bonus tolerance equal to the amount by which the actual feature size departs from its maximum material limit. A larger hole therefore gains extra positional tolerance while still accepting the mating fastener.

Question 41Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

In the AWS classification E60XX for a covered electrode, what does the first two digits (60) indicate?

  1. The electrode's coating thickness in millimetres
  2. Maximum current-carrying capacity in amperes
  3. Yield strength of the core wire in MPa
  4. Minimum tensile strength of the deposited weld metal in ksi (thousand pounds per square inch) Correct answer.

Explanation

In the AWS A5 electrode designation, the first two digits give the minimum tensile strength of the deposited weld metal in thousands of pounds per square inch (ksi). For example, E60XX deposits metal with a minimum tensile strength of 60 ksi, roughly 410 MPa. The remaining digits describe position and coating/current type, not strength.

Question 42Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

A plain carbon steel contains 0.8% carbon. Which microstructural description best fits this composition at room temperature under equilibrium cooling?

  1. Predominantly delta ferrite
  2. Pearlitic, essentially all lamellar ferrite and cementite Correct answer.
  3. Fully ferritic with no carbide phase
  4. Fully austenitic

Explanation

At about 0.8% carbon, plain carbon steel corresponds to the eutectoid composition. On slow equilibrium cooling, austenite transforms entirely into pearlite, a lamellar mixture of ferrite and cementite. No free ferrite or free cementite network forms at this exact composition.

Question 43Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

Why is a small amount of silicon added during steelmaking for welding-grade steel?

  1. To make the steel strongly magnetic
  2. To lower the melting point below that of aluminium
  3. To act as a deoxidiser and improve soundness of the steel Correct answer.
  4. To increase the carbon content of the melt

Explanation

Silicon is a strong deoxidiser: it combines with dissolved oxygen to form silicates that leave the melt, reducing porosity and improving steel soundness. This is why controlled silicon levels are specified in welding-grade steels. It does not raise carbon or set magnetic behaviour.

Question 44Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

Which of the following is the main reason copper and its alloys require special care during fusion welding?

  1. They contain large amounts of chromium carbide
  2. They cannot be joined by any arc process
  3. They have very high thermal conductivity, so heat is drawn away rapidly from the weld zone Correct answer.
  4. They are strongly ferromagnetic and arc blow is unavoidable

Explanation

Copper has very high thermal conductivity, so heat is conducted away from the joint quickly, demanding higher heat input and preheat to achieve fusion. This property, plus high thermal expansion, makes copper welding more demanding than steel. Copper is not ferromagnetic and can be arc welded with correct procedures.

Question 45Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

In the iron-carbon equilibrium diagram, what is the significance of the A1 (eutectoid) temperature near 723 °C in plain carbon steel?

  1. It is the temperature at which pure iron melts
  2. It is the temperature at which austenite transforms to pearlite on slow cooling Correct answer.
  3. It is the temperature at which cementite becomes non-magnetic
  4. It is the temperature at which carbon begins to evaporate

Explanation

The A1 line marks the eutectoid reaction where austenite decomposes into ferrite and cementite (pearlite) during slow cooling, at about 723 °C. It is a key reference for heat treatment and for predicting weld heat-affected zone structures. Melting of pure iron occurs much higher, near 1538 °C.

Question 46Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

A weld is made on a medium-carbon steel containing 0.45% carbon. Which problem is most likely if no preheat is used?

  1. Excessive softness in the heat-affected zone
  2. Complete loss of carbon from the steel
  3. Formation of hard, crack-sensitive martensite in the heat-affected zone Correct answer.
  4. Spontaneous conversion of the steel to austenite at room temperature

Explanation

Higher carbon content increases hardenability, so rapid cooling of the heat-affected zone can produce hard martensite that is prone to cracking. Preheat slows the cooling rate and reduces this risk. The other options describe effects that do not occur under normal welding conditions.

Question 47Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

What is the principal effect of hydrogen dissolved in weld metal on a high-strength steel joint?

  1. It increases the tensile strength of the weld metal
  2. It prevents slag formation
  3. It converts ferrite into austenite permanently
  4. It can cause delayed cracking, often called hydrogen-induced cold cracking Correct answer.

Explanation

Hydrogen picked up from moisture or coatings can diffuse into the weld and heat-affected zone and cause delayed cold cracking, especially in high-strength or thick sections. Control relies on low-hydrogen consumables, preheat and drying of electrodes. Hydrogen does not raise tensile strength or alter phase stability in that way.

Question 48Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

Which characteristic distinguishes austenitic stainless steel from ferritic stainless steel?

  1. Ferritic grades have a face-centred cubic structure
  2. Ferritic grades are always non-magnetic
  3. Austenitic grades are non-magnetic in the annealed condition and have a face-centred cubic structure Correct answer.
  4. Austenitic grades contain no chromium

Explanation

Austenitic stainless steels, stabilised by nickel, have a face-centred cubic structure and are essentially non-magnetic when annealed. Ferritic grades have a body-centred cubic structure and are magnetic. Both families rely on chromium for corrosion resistance.

Question 49Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

What is the main purpose of adding titanium or niobium to a stainless steel electrode?

  1. To lower the arc voltage
  2. To increase the carbon content of the weld metal
  3. To make the weld metal ferromagnetic
  4. To stabilise carbon as carbides and prevent chromium carbide precipitation at grain boundaries Correct answer.

Explanation

Titanium and niobium have a stronger affinity for carbon than chromium does, so they form stable carbides instead of allowing chromium carbides to precipitate at grain boundaries. This prevents chromium depletion and sensitisation, preserving corrosion resistance. They do not raise carbon or affect magnetism.

Question 50Materials, Ferrous and Non-Ferrous Metals, and Heat Effects of Welding

Which of the following best describes the effect of a rapid cooling rate on the heat-affected zone of a carbon steel weld?

  1. It converts the steel to cast iron
  2. It tends to produce a finer, harder structure with higher cracking susceptibility in higher-carbon steels Correct answer.
  3. It produces a coarser grain structure and lower hardness
  4. It eliminates the heat-affected zone entirely

Explanation

Faster cooling after welding suppresses diffusion, giving finer transformation products and higher hardness in the heat-affected zone. In higher-carbon or higher-alloy steels this raises the risk of cold cracking. Slow cooling, by contrast, gives softer, coarser structures.