CWB Welding Inspector Level III Exam 2023/2024 with 100%Correct Answers.

CWB Welding Inspector Level III Exam 2023/2024 with 100%Correct Answers. Which of the following metals has the highest thermal conductivity? (a) carbon steel (b) stainless steel (c) aluminum - Correct Answer-(c) The Ellingham diagram (a) is a plot of thermal conductivity against temperature, (b) shows the free energy of oxide formation against temperature. (c) shows the rate of oxidation of metals against temperature. - Correct Answer-(b) True or False? A metal with a high negative free energy of oxide formation will generally require greater shielding from the atmosphere during welding. - Correct Answer-True Electricity can be conducted by: (a) atoms and electrons. (b) electrons and ions. (c) only ions. - Correct Answer-(b) Which of the following elements is often present in submerged arc fluxes to improve arc stability? (a) copper (b) potassium (c) nickel (d) tungsten - Correct Answer-(b) Thoria is added to tunsten electrodes for what purpose? - Correct Answer-To increase thermionic emission by lowering the work function. True or False? All pure metals have the same crystal structure. - Correct Answer-False. Metals generally have one of three basic structures. Which crystal structure(s) is (are) composed of close-packed planes? - Correct AnswerFCC and HCP The real strength of metals is lower than the theoretical value because: (a) real crystals always fracture along specific crystal planes. (b) grain boundary sliding occurs. (c) the presence of dislocations facilitates slip. - Correct Answer-(c) CWB Welding Inspector Level III Exam 2023/2024 with 100%Correct Answers. Multiplication and subsequent congestion of moving dislocations causes: (a) elastic extension. (b) work or strain hardening. (c) a drop in the yield stress. - Correct Answer-(b) Which of the following elements are most likely to form interstitial solid solutions? (a) copper (b) nickel (c) carbon - Correct Answer-(c) If FCC iron has a denser structure than BCC iron, why does it have a higher solubility for carbon? - Correct Answer-The preferred site for carbon in BCC iron is smaller than that in FCC iron. If two metals have complete mutual solid solubility how many phases are formed in the solid- one or two? - Correct Answer-One How many phases are there in a eutectic- one or two? - Correct Answer-Two Without referring to the text, draw the phase diagram for a eutectic system with limited mutual solid solubility of the two components. - Correct Answer-Refer to Figure 6.6(Module 20-2014, page 18) Using the portion of the iron-carbon phase diagram in Figure 6.10(Module 20-2014, page 21), use the lever rule to determine the precentage of ferrite and eutectoid pearlite present in a slowly cooled 0.2% carbon steel. - Correct Answer-About 25% pearlite and 75% ferrite. Here the tie line begins at 0.0%C (α ferrite) and ends at 0.08%C (pearlite). The fulcrum for the lever rule is at 0.2%C % pearlite = (0.2%C - 0.0%C)/).8%C - 0.0%C) x 100% % pearlite = (0.2/0.8) x 100% % pearlite = 25% Which of the following metals has the highest work hardening coefficient? (a) 70/30 brass (b) aluminum (c) copper (d) low carbon steel - Correct Answer-(a) True or False? Recrystallization always involves the formation of a new phase. - Correct Answer-False To get recovery and recrystallization the metal must have been previously (a) quenched. (b) heated. (c) cold worked. - Correct Answer-(c)