CNC Ferrous & Non-Ferrous Material Properties 4

Question 1

In CNC machining, which steel designation indicates a free-machining grade with improved chip breaking due to added sulfur?

Accepted Answer

1215

Answer

AISI 1215 is a free-machining steel with added sulfur and phosphorus that form inclusions, promoting short chips and reduced tool wear.

Question 2

What is the effect of annealing on a cold-worked steel part?

Accepted Answer

Relieves internal stresses and restores ductility

Answer

Annealing heats the steel and allows slow cooling, recrystallizing the grain structure, relieving residual stresses, and restoring ductility.

Question 3

Which of the following best describes the property of malleability?

Accepted Answer

Ability to be hammered or rolled into thin sheets without fracturing

Answer

Malleability is the ability of a material to undergo plastic deformation in compression (rolling, forging, hammering) without fracturing.

Question 4

Which type of cast iron has superior tensile strength due to its spheroidal graphite morphology?

Accepted Answer

Ductile (nodular) cast iron

Answer

Ductile iron (also called nodular iron) has graphite in spherical nodules rather than flakes, which greatly reduces stress concentrations and improves tensile strength.

Question 5

Bronze is an alloy primarily composed of:

Accepted Answer

Copper and tin

Answer

Bronze is traditionally copper alloyed with tin, though modern 'bronzes' may substitute other elements while keeping copper as the base.

(CNC) Computer Numerical Control Machinist Technical Practice Test

(CNC) Computer Numerical Control Machinist Technical Practice Test

CNC Ferrous & Non-Ferrous Material Properties 4