Explain briefly how steel is made, starting with iron ore, coke, and limestone.

Why is it that castings made from pressure die casting are likely to be stronger than those made using the sand casting process?

Derive the formula for the rate of change in total energy change (i.e., the derivative of $\Delta G$ with respect to $r$ ) as a function of the radius $r$ of the solid nucleus. Begin with Equation 9-1. Numerically, how is the critical point at which solidification proceeds defined?

Explain the green sand molding process.

The usual method of measuring a vacuum in the United States vacuum pump industry is in inches of mercury. For example, atmospheric pressure is $29.92\ \text{inches}$ of mercury. Convert the pressure found in the example to in $\mathrm{Hg}$

The solubility of hydrogen in liquid aluminum at $715^{\circ} \mathrm{C}$ is found to be $1 \mathrm{~cm}^3 /$ ( $100 \mathrm{~g} \mathrm{Al})$. If all of this hydrogen precipitated as gas bubbles during solidification and remained trapped in the casting, calculate the volume percent gas in the solid aluminum.

Find the solubility of hydrogen in liquid aluminum just Explain why this process is often used to cast turbine blades.

Molten copper at atmospheric pressure contains $0.01 \mathrm{wt} \%$ oxygen. The molten copper is placed in a chamber that is pumped down to $1 \mathrm{~Pa}$ to remove gas from the melt prior to pouring into the mold. Calculate the oxygen content of the copper melt after it is subjected to this

A liquid cast iron has a density of $7.65 \mathrm{~g} /$ $\mathrm{cm}^3$. Immediately after solidification, the density of the solid cast iron is found to be $7.71 \mathrm{~g} / \mathrm{cm}^3$. Determine the percent volume change that occurs during solidification. Does the cast iron expand or contract during solidification?

Liquid magnesium is poured into a $2 \mathrm{~cm}$ $\times 2 \mathrm{~cm} \times 24 \mathrm{~cm}$ mold and, as a result of directional solidification, all of the solidification shrinkage occurs along the $24-\mathrm{cm}$ length of the casting. Determine the length of the casting immediately after solidification is complete.

In the context of stainless steel making, what is argon oxygen decarburization?

What is Sievert's Law? How can gas porosity in molten alloys be removed or minimized?

Give examples of materials that expand upon solidification.

A $2\ \text{in.}$ $\times 8$ in. $\times 10$ in. iron casting is produced and, after cooling to room temperature, is found to weigh $43.9 \mathrm{lb}$. Determine (a) the percent of shrinkage that must have occurred during solidification and (b) the number of shrinkage pores in the casting if all of the shrinkage occurs as pores with a diameter of $0.05$ in.