Material Science - short answer questions from AMIE exams

A brass plate contains a steel screw and it is being used in a marine environment. Which of the two metals would corrode faster and why?

The steel is on the higher side of the Galvanic series as compared to brass, so it will corrode faster.

What is the weight % of carbon in low carbon steel?

The percentage of carbon in low carbon steel is 0.05 to 0.3.

What is carburizing?

Carburizing is the diffusion or impregnation of carbon on the surface.

Whether duralumin is wrought or cast alloy?

It is a wrought alloy.

Name at least two mechanisms of plastic deformation.

Slip and Twinning. The key difference between slip and twinning is that during a slip, all atoms in a block move the same distance whereas, in twinning, the atoms in each successive plane in a block move through different distances that are proportional to their distance from the twinning plane.

Which of the two main mechanisms of plastic deformation requires greater shear stress to deform.

Slip

If you wound annealed MS and copper wire around your finger one of the two will not form a smooth circular. Which one?

Mild steel

Before cold working of AL alloy, it is heated to about 584⁰C and then quenched or it should be heated to a lower temperature of 100 to 200⁰C and then air-cooled?

They are heated to 584⁰C and quenched

For which type of fracture, the direction of crack propagation is very nearly perpendicular to the direction of applied tensile stress?

Brittle type of fracture. A brittle fracture is the fracture of a metallic object or other material without appreciable prior plastic deformation. It is a break in a brittle piece of metal that failed because stress exceeded cohesion.

Brass and Bronze are alloys of copper. What are the other constituents in these alloys?

Brass has other constituents; Zinc, Nickel and Lead Bronze has other constituents; Tin Phosphorous and Aluminium.

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