17. (a) Why are welds more difficult on sheet iron and steel than on some of the heavier pieces?
(b) What can be used as a “filler-rod” on sheet metal work?
18. (a) What difficulty is generally encountered, when making a long weld like on a steel tank?
(b) How can this be overcome?
(c) Why do the open ends on sheet steel welds overlap in welding when same class of work on cast iron separates?
19. (a) What causes steel welds to carbonize?
(b) What usually causes a burnt steel weld?
20. Describe fully how a broken automobile frame can be welded and re-enforced to make it stronger than originally.
LECTURE NUMBER ELEVEN
Subject—Steel Welding
(Part Three)
21. (a) What kind of a “filler-rod” is used in welding cast steel?