Assignment No. 08

1) Weldability of aluminium alloys is limited by a) High melting point b) Low thermal expansion coefficient c) Low oxidation tendency d) High oxidation tendency

Correct Answer- d) High oxidation tendency

2) Thermal softening of HAZ of work hardenable aluminium alloys occurs due to a) Easy melting b) Dissolution of precipitates c) Grain refinement d) recrystallization and grain growth

Correct Answer- d) recrystallization and grain growth

3) Aluminium alloys with narrow solidification temperature range results in a) Wide HAZ b) Narrow HAZ c) Narrow partial melting zone d) High solidification cracking tendency

Correct Answer- c) Narrow partial melting zone

4) Solidification cracking of aluminium alloys is not promoted by a) High thermal expansion coefficient b) High solidification temperature c) Coarse grain d) Fine grain

Correct Answer- d) Fine grain

5) The solidification cracking tendency of austenitic stainless steel is reduced by a) Austenite b) Delta ferrite c) Pearlite d) Bainite

Correct Answer- b) Delta ferrite

6) Generally, residual stress along the weld in fusion weld joint is a) Tensile at the weld b) Compressive at the weld c) Tensile away from fusion boundary d) None of above Correct Answer- a) Tensile at the weld

7) Compressive residual stresses in weld joints a) Decreases tensile strength b) Increases cracking tendency c) Increases fatigue strength d) Coarsen the grain structure

Correct Answer- c) Increases fatigue strength

8) Arc oscillation helps in controlling the solidification cracking due to a) Reduction in residual stress b) Modification in grain structure c) Strengthening of weld metal d) Increases segregation tendency

Correct Answer- b) Modification in grain structure

9) Lamellar tearing is encouraged by a) Low hardness b) Inclusions of high aspect ratio c) Low hydrogen d) High compressive residual stress

Correct Answer- b) Inclusions of high aspect ratio

10) Cold cracking promoted by a) Bainitic structure b) High hardness c) Low hydrogen content d) High compressive residual stress

Correct Answer b) High hardness