Manufacturing Midterm

According to Chvorinov’s rule, solidification time is proportional to:

(Volume/Surface Area)²

Which shape solidifies fastest if all have equal volume?

Cube

Shrinkage during casting occurs due to:

Contraction of molten, phase change, and solid metal

Which type of cast iron expands during solidification?

Gray cast iron

The upper half of a sand mold is called the:

Cope

Which mold feature acts as a reservoir for molten metal?

Riser

Which equation relates velocity and height in gating design?

Bernoulli’s equation

What does a high Reynolds number indicate in casting flow?

Turbulent flow

What is the main consequence of turbulence in gating?

Air entrapment and dross formation

Fluidity of molten metal increases with:

Higher superheat

Which cast iron is hardest and most brittle?

White cast iron

Which cast iron is heat treated to improve ductility?

Malleable iron

Which factor most decreases fluidity?

High viscosity

What is the function of a core in casting?

To form internal cavities or holes

The parting line in a mold divides:

Cope and drag

Sand casting is considered:

An expendable-mold, permanent-pattern process

Which of the following is not an expendable mold process?

Die casting

A major advantage of sand casting is:

Low cost for small production quantities

Shell molding produces:

High dimensional accuracy and smooth surface finish

In evaporative pattern casting, the pattern material is:

Polystyrene

Investment casting is also known as:

Lost wax process

Investment casting is best suited for:

Complex parts with fine detail

A disadvantage of investment casting is:

High cost and long cycle time

Which of the following castings can achieve the best surface finish?

Investment casting

Continuous casting is mainly used for:

Steel and nonferrous metal strips

Permanent molds are commonly made of:

Steel or cast iron

Die casting involves injecting molten metal:

Under high pressure

Hot chamber die casting is suitable for:

Low melting point metals (zinc, tin, lead)

Centrifugal casting is used for:

Pipes, tubes, and rings

Which of the following reduces porosity in castings?

Using internal or external chills

Within which region on the stress–strain curve is Hooke’s law valid?

Only in the elastic region.

Which property is a measure of stiffness?

Modulus of Elasticity (E)

What does the 0.2% offset method determine?

Yield strength.

Which of the following describes ductile materials?

Can undergo large deformation before fracture.

Which of the following best defines Poisson’s ratio?

Negative ratio of lateral strain to axial strain.

Which formula expresses Hooke’s law?

σ = E ε

Which region of the stress–strain curve shows permanent deformation?

Plastic region.

Which parameter represents energy absorption before yielding?

Modulus of Resilience.

Which parameter represents total energy absorption before fracture?

Modulus of Toughness.

Which of the following tests best determines the strength of brittle materials like ceramics?

Three- or four-point bending test.

In the plastic region, the stress–strain relation is represented by:

σ = K εⁿ

The strain hardening exponent (n) controls what property?

Material’s ability to strain harden before necking.

The onset of necking occurs when:

dσ/dε = σ

What happens to material ductility as temperature increases?

It increases.

What happens to yield strength as temperature increases?

It decreases.

The strain rate sensitivity exponent (m) increases with:

Temperature.

Residual stresses are most likely to form in:

Rolled sheets, drawn rods, thin-walled tubes.

Residual stresses can be relieved by:

Annealing or stretching.

In the equation σ = C ε̇ᵐ, a higher m value means:

Greater resistance to necking.

During plastic deformation, volume:

Remains constant.

True stress is calculated using:

Instantaneous area.

True strain is defined as:

ln(L/L₀)

Which of the following statements about true stress–strain curves is correct?

Slope is always positive and decreases with increasing strain.

Which of the following materials has the highest stiffness?

Material with highest modulus of elasticity.

The main advantage of casting over other processes is:

Ability to produce complex and large shapes.

The region between liquidus and solidus lines in alloys is known as:

Mushy zone.

For pure metals, freezing occurs:

At a constant temperature.

The lever rule is used to:

Determine the weight fraction of each phase.

Which solidification structure grows from the mold walls inward?

Columnar grains.

When the solidifying front pushes solute toward the center, it’s called:

Normal segregation.

The difference in solute composition within a single dendrite is called:

Microsegregation.

The difference in solute composition across the whole casting is called:

Macrosegregation.

A eutectic alloy has a freezing range of:

Zero (solidifies at one temperature).

Which process involves pouring molten metal into a mold cavity?

Casting.

What determines the solidification time in an alloy?

Width of the mushy zone.

What does the lever rule require to apply?

Compositions at solidus and liquidus lines.

What type of grain forms at the mold wall in pure metals?

Preferentially oriented columnar grains.

What is a major factor influencing grain size and uniformity in castings?

Cooling rate.