Complete the following sentences: • A characteristic feature of fusion welding is: a) molten metal b) low-voltage discharge c) inert atmosphere 48 2. Furnace heating is usually employed in a) friction joining b) diffusion bonding c) ultrasonic joining 3. The consumable electrode is made a) negative b) positive c) neither 4. Total energy input in all welding processes is a) is greater than required to produce a joint b) is smaller than required to produce a joint c) equals to required to produce a joint 5. Reactions of most metals with the atmosphere or other nearby metals can 1) improve the properties of a welded joint b) make the properties of a welded joint worse c) never influence the properties of a welded joint 6. The most common gas used in gas-shielded metal-arc and gas-shielded tungsten-arc welding is a) argon b) oxygen c) carbon dioxide 7. If not controlled, residual stress results in a) precipitation processes in welded structures, b) freezing of the weldmetal c) bowing or distortion of the weldment. True or false? 1. There is always a welding pool in solid-phase welding processes. 2. Total energy input in all welding processes is greater than needed to produce a weld. 3. Reactions of metals with the atmosphere or other nearby metals are favorable to the properties of a welded joint. 4. Fluxes and inert atmospheres play a protective role and prevent oxidation. 5. The heat-affected zone is a region with unaltered properties. 6. Residual stress is present in all welded structures.