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100+ Free IIW IWI-C Practice Questions

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2026 Statistics

Key Facts: IIW IWI-C Exam

100

Practice Questions

OpenExamPrep

~5.5 hours

Written + Oral/Practical

IIW IAB-041

60%

Minimum Pass Mark

IIW IAB-041

Highest

Inspector Tier (above IWI-S/IWI-B)

IIW IAB-041

ISO 5817

Quality Levels B/C/D

ISO

Global

Delivered via national ANBs

IIW/IAB

The IIW International Welding Inspector - Comprehensive (IWI-C) is the highest of the three IIW welding-inspector levels defined in guideline IAB-041, above Standard (IWI-S) and Basic (IWI-B). Examination is conducted through national Authorised National Bodies (ANBs) and combines written multiple-choice papers with oral and practical assessment, about 5.5 hours in total, with a 60% minimum pass mark per the IIW/EWF guideline. The IWI-C holder has intimate knowledge of welding metallurgy, process control, design and fitness-for-service, fracture and defect significance, NDE coordination and method selection, and codes/QA systems, and is qualified to manage the entire welding-inspection activity, develop inspection and quality plans, and handle non-conventional applications not covered by codes. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample IIW IWI-C Practice Questions

Try these sample questions to test your IIW IWI-C exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a C-Mn steel weld, which microconstituent forming in the weld metal is generally most beneficial to low-temperature toughness?
A.Grain-boundary ferrite
B.Acicular ferrite
C.Upper bainite
D.Widmanstatten ferrite (ferrite with aligned second phase)
Explanation: Acicular ferrite nucleates intragranularly on inclusions to form a fine, randomly oriented, interlocking microstructure that resists cleavage crack propagation, giving the best combination of strength and toughness in ferritic weld metal. Inspectors specify consumables and heat input to maximise its proportion.
2Hydrogen-induced (cold) cracking in ferritic steel welds requires the simultaneous presence of which three factors?
A.High heat input, austenitic structure and oxygen
B.Diffusible hydrogen, a susceptible (hard) microstructure and tensile stress
C.Sulphur, low restraint and preheat
D.Copper contamination, low carbon equivalent and slow cooling
Explanation: Hydrogen (cold) cracking needs three coincident conditions: sufficient diffusible hydrogen, a crack-susceptible hard microstructure (typically martensite from rapid cooling), and tensile stress, usually at temperatures below about 150 C. Removing any one factor (e.g. preheat to lower hydrogen and soften the HAZ) prevents it.
3Solidification (hot) cracking in the weld metal is most strongly promoted by high levels of which residual elements forming low-melting-point films?
A.Chromium and molybdenum
B.Sulphur and phosphorus
C.Nickel and copper
D.Titanium and niobium
Explanation: Sulphur and phosphorus form low-melting-point eutectic films that remain liquid at grain boundaries while the surrounding metal contracts, opening centreline solidification cracks. Manganese is added partly to tie up sulphur as higher-melting MnS, and a favourable Mn/S ratio reduces hot-cracking risk.
4Using the IIW carbon equivalent CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15, a steel with C 0.18, Mn 1.2, Cr 0.10, Mo 0.05, V 0, Ni 0.10, Cu 0.10 has a CEV closest to:
A.0.32
B.0.41
C.0.55
D.0.27
Explanation: CEV = 0.18 + 1.2/6 + (0.10+0.05+0)/5 + (0.10+0.10)/15 = 0.18 + 0.20 + 0.03 + 0.0133 = 0.41. A CEV around 0.41 indicates moderate hardenability, so preheat and hydrogen control are typically required to avoid HAZ cold cracking.
5Which test is used specifically to assess a steel plate's susceptibility to lamellar tearing by measuring through-thickness ductility?
A.Charpy V-notch impact test
B.Short transverse (through-thickness) tensile reduction-of-area test
C.Vickers hardness traverse
D.Nick-break test
Explanation: Lamellar tearing is a through-thickness phenomenon driven by planar non-metallic inclusions; the short transverse tensile test measures reduction of area in the through-thickness (Z) direction. Steels specified with a minimum Z-quality (e.g. Z25, Z35 per EN 10164) resist lamellar tearing under high through-thickness restraint.
6In austenitic stainless steel welds, a controlled small amount of delta-ferrite (typically 5-10 FN) in the weld metal is desired primarily to:
A.Increase magnetic permeability for inspection
B.Resist solidification (hot) cracking
C.Improve room-temperature ductility
D.Raise the melting point of the weld
Explanation: A few percent of delta-ferrite dissolves sulphur and phosphorus and disrupts continuous low-melting films at austenite grain boundaries, strongly reducing solidification cracking. Filler metals are balanced (via the WRC-1992 or Schaeffler diagram) to give roughly 5-10 Ferrite Number while avoiding excess ferrite that harms corrosion/toughness.
7Sensitisation of austenitic stainless steel, leading to intergranular corrosion, is caused by:
A.Excessive nickel forming brittle phases
B.Chromium-carbide precipitation at grain boundaries depleting adjacent chromium
C.Hydrogen pickup during welding
D.Formation of sigma phase at low temperature
Explanation: Holding austenitic stainless steel in the roughly 550-850 C range (e.g. in the HAZ) precipitates chromium carbides (Cr23C6) at grain boundaries, depleting the adjacent matrix of chromium below the level needed for passivity and causing intergranular attack. Low-carbon (L) grades or Ti/Nb stabilised grades resist sensitisation.
8Reheat (stress-relief) cracking is most commonly associated with which materials during post-weld heat treatment?
A.Plain low-carbon mild steels
B.Creep-resistant Cr-Mo-V and certain stabilised steels
C.Aluminium alloys
D.Austenitic stainless steels at room temperature
Explanation: Reheat cracking occurs in the coarse-grained HAZ of creep-resistant low-alloy steels (notably Cr-Mo-V) and some stabilised grades when carbide-forming elements precipitate during PWHT, strengthening grain interiors so relaxation strain concentrates at grain boundaries. Controlling restraint, grinding stress raisers and selecting resistant grades reduces the risk.
9The primary metallurgical purpose of preheating a thick C-Mn steel joint before welding is to:
A.Increase the deposition rate of the filler
B.Slow the cooling rate to reduce HAZ hardness and allow hydrogen to escape
C.Improve the arc's electrical efficiency
D.Increase weld penetration depth only
Explanation: Preheat lowers the cooling rate through the transformation range, reducing the formation of hard martensite in the HAZ and giving diffusible hydrogen more time to escape. Both effects directly reduce hydrogen (cold) cracking risk, which is why preheat is a key essential variable.
10What is the typical maximum HAZ hardness limit (Vickers HV10) specified to guard against hydrogen cracking and sour-service issues in many ferritic structural and pipeline applications?
A.150 HV
B.248-350 HV depending on application
C.600 HV
D.100 HV
Explanation: Many fabrication codes limit HAZ hardness to around 350 HV10 for general structural steel, while sour (H2S) service per NACE/ISO 15156 commonly imposes 248 HV (about 22 HRC). Hardness traverses across the HAZ are a standard control to confirm the welding procedure keeps hardness below the specified limit.

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