QUIZ TBT 412 Metallurgy of Forensic Crash Course Session 2010/2011 MULTICHOICE QUESTION [This quiz has FIFTY

(50) questions. Answer any TWENTY FIVE (25) questions only.] 1. When open site working, serious porosity in metal arc welds is brought to your attention. What would you investigate? a. Electrode type b. Power plant type c. Electrode storage d. Day temperature The steel composition in a structural contract is changed from 0.15% carbon 0.6% manganese, to 0.2% carbon 1.2% manganese. This might influence the incidence of: a. Porosity b. Cracking in the weld area c. Undercut for fillet welds d. Lack of fusion defects Stress relief is not helpful in which of the following cases? a. In improving resistance to stress corrosion. b. In improving dimensional stability after machining. c. In lowering the peak residual stresses. d. In softening the metal. Which one of the following statements is correct? a. Preheating increases hardness b. Preheating increases cooling c. Preheating increases dilution d. Preheating increases shrinkage stress Cold cracking is most likely to occur in a weldment if: a. The rate of cooling is too fast. b. The rate of cooling is too slow. c. It lacks ductility at high temperatures. d. Impurities are present at its grain boundaries. One of the reasons for excluding hydrogen from the weld metal is to prevent the weld from: a. Cracking b. Cooling slowly c. Cooling quickly d. Expanding When a metal regains its original shape when stress acting upon it is removed, the metal is said to have: a. Ductility b. Plasticity c. Malleability d. Elasticity

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One purpose of a microscopic examination of a weld is to establish the: a. Strength of the weld b. Number of alloying elements c. Grain size d. Number of runs used What is the most common cause of failure in root bend tests? a. Too high a current setting. b. Too long a pause in the down cycle of the weave. c. Lack of fusion and penetration. d. Too high a travel speed. Degreasing components is essential for quality welding but some agents may: a. Cause corrosion problems b. Give off phosgene gas c. Leave residues d. All the above Which of the following elements has the greater effect on the hardenability of a steel plate? a. Molybdenum b. Chromium c. Titanium d. Carbon Welds made with high heat inputs show a reduction in which of the following properties? a. Ductility b. Toughness c. Fatigue strength d. Mechanical strength In the welding of austenitic pipework the bore is usually purged with argon to: a. Prevent formation of porosity in the weld b. Prevent burn-through in the root run c. Prevent oxidation of the root bead d. Eliminate the formation of hydrogen Which one of the following types of steel would give rise to the formation of porosity when autogenously welded with an arc process? a. Fully killed steel b. Semi killed steel c. Rimming steel d. Fine grained steel In the welding of austenitic stainless steels, the electrode and plate material can be purchased with low carbon contents. The reason for this is to prevent: a. Cracking in the heat affected zone b. The formation of chromium carbides c. Cracking in the weld metal d. Distortion

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In a steel that has improved creep properties at elevated temperatures, which one of the following elements helps in this improvement? a. Tungsten b. Manganese c. Molybdenum d. Carbon Welding procedures may require welds to be deposited at a controlled rate of heat input. High heat inputs would: a. Have poor profile b. Have larger grain size c. Have high hardness in the HAZ d. Have low elongation properties In a tensile test a brittle material would be indicated if the fracture surface: a. Shows a reduction in size b. Is flat and featureless c. Breaks in the parent material d. Breaks at 45 to the load Incomplete root penetration in a butt joint could be caused by: a. Excessive root face width b. Excessive root gap size c. Low current setting d. Both A and C Incomplete root fusion would certainly be caused by: a. Linear misalignment b. Incorrect tilt angle c. Differing root face widths d. All of the above Slag inclusions would occur with: a. Manual metal arc b. Metal inert gas c. Submerged arc welding d. Both A and C Undercut is principally caused by: a. Excessive amps b. Excessive volts c. Excessive travel speed d. All the above Undercut is normally assessed by: a. Its depth b. Its length c. It's blending d. All the above

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A planar defect is: a. Incomplete fusion defects b. Slag inclusion c. Incomplete penetration d. Both A and C Defects outside the limits specified in a standard should always be: a. Repaired b. Reported to 'a senior person' c. Assessed along with other defects d. All the above The main cause of porosity in welded joints is: a. Poor access b. Loss of gas shield c. 'Dirty' materials d. All the above Cracks in welds may be due to: a. Solidification problems b. Hydrogen problems c. Excessive stresses d. All the above With reference to a root penetration bead you would certainly assess: a. Root fusion and penetration b. Root concavity c. Burn through d. All the above In a fatigue failure the appearance of the fracture surface is characteristic. It would be: a. Rough and torn b. 'Chevron'-like c. Smooth d. None of the above Overlap in welds could be influenced by: a. Poor welding technique b. Welding process c. Welding position d. All the above Which of the following may be classed as a more serious defect? a. Slag inclusions b. Fusion defects (inter-run) c. Fusion defects (surface) d. Porosity

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A metallurgical problem most associated with submerged arc welding is: a. Hydrogen cracking in the HAZ b. Solidification cracking in the weld metal c. Hydrogen cracking in the weld metal d. Lamellar tearing in the weld metal The likelihood of brittle fracture in steels will increase with: a. A large grain formation b. A reduction of in-service temperature to sub zero temperatures c. Ferritic rather than austenitic steels d. All the above Repair welding is often more difficult than production welding due to: a. The material being ingrained with in-service contaminants b. Restricted access within the repair area c. The possible position of the weld repair d. All the above Hydrogen cracking in the weld metal is likely when welding: a. Carbon manganese steels b. Stainless steels c. Micro alloyed steels (HSLA) d. Low carbon steels Porosity is caused by: a. Entrapped slag in the solidifying weld b. Entrapped gas in the solidifying weld c. Entrapped metallic inclusions in the solidifying weld d. None of the above Ultrasonic testing is more advantageous in detecting which of the following weld imperfections, over other NDT methods? a. Lack of sidewall fusion b. Surface undercut c. Incompletely filled groove d. Overlap The presence of iron sulphide in the weld metal is most likely to produce which of the following upon contraction of the weld? a. Solidification cracking b. Hydrogen cracking c. Intergranular corrosion d. Stress corrosion cracking The important point of high temperature steels is that: a. They can withstand creep failure. b. They may suffer re-heat cracking problems. c. They may suffer loss of toughness. d. All the above.

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An austenitic stainless steel may suffer: a. Weld decay. b. Sensitization. c. Solidification cracking. d. All the above. The most serious defect types are: a. Planar. b. Cracks. c. Lack of fusion. d. All the above. Chromium, when added to steel as an alloying element, has the effect of making the alloy more: a. Ductile. b. Plastic. c. Hardenable. d. Malleable. Which of the following defects would you not expect to find by visual inspection of welds? a. Linear slag inclusions. b. Undercut. c. Overlap. d. Linear misalignment. Stress relieving is not helpful in which of the following cases? a. Improving resistance to stress corrosion cracking. b. Improving dimensional stability after machining. c. Lowering the peak residual stress. d. Softening the steel. Percentage elongation of a metal undergoing a tensile test is a measure of: a. Elasticity. b. Plasticity. c. Ductility. d. Malleability. Weld decay in stainless steels can be avoided by: a. Stress relieving. b. Slow cooling after welding. c. Addition of more manganese to the steel. d. Addition of titanium to the steel. The purpose of pre-heating low alloy steel pipes before electric arc welding is to: a. Refine grain structure. b. Relieve internal stress. c. Retard rapid cooling. d. Regulate excessive expansion.

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Which of the following can arise from copper inclusions in a mild steel weld? a. Weld metal cracks. b. HAZ cracks. c. Lack of fusion. d. Porosity.

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