AME 1 Q4

Answer:

B. 304: Interior fittings, railings; 316: Hull components, bilge pumps

Explanation:

• 304 stainless steel is often used for interior fittings and railings on marine vessels due to its good corrosion resistance in less severe environments.
• 316 stainless steel is better suited for external components exposed to saltwater, such as hull components and bilge pumps, due to its superior resistance to chloride-induced corrosion.

Options A, C, and D contain incorrect pairings of steel grade and application.

Why the other options are incorrect:

• A. 304: Kitchen sinks, electrical wiring; 316: Propellers, engine components: While both 304 and 316 have their applications, electrical wiring is typically not made from stainless steel due to cost and conductivity considerations. Additionally, propellers often require materials with higher strength and specific corrosion resistance properties, which 316 might not fully provide.
• C. 304: Propellers, rudder; 316: Kitchen appliances, decorative trim: Propellers and rudders are exposed to harsh marine environments and require superior corrosion resistance, which is better provided by 316 stainless steel. 304 is more suitable for interior applications like kitchen appliances and decorative trim.
• D. 304: Engine components, structural beams; 316: Interior lighting, ventilation ducts: Engine components often require materials with specific heat resistance and mechanical properties, which 304 might not fully provide. Interior lighting and ventilation ducts are generally not exposed to the same level of harsh conditions as external components and can be adequately served by 304 stainless steel.

Answer:

A. Iron (60-70%), Chromium (16-18%), Nickel (8-10%)

Explanation:

Austenitic stainless steel is primarily composed of iron, with chromium being the key alloying element providing corrosion resistance. Nickel is added to stabilize the austenitic structure and improve properties like ductility and toughness. While the exact percentages can vary depending on the specific grade, the general composition falls within the ranges provided in option A.

Why the other options are incorrect:

• B. Copper (50%), Zinc (30%), Tin (20%): This composition describes brass, not stainless steel.
• C. Aluminum (70%), Magnesium (20%), Silicon (10%): This composition is closer to an aluminum alloy, not stainless steel.
• D. Titanium (60%), Vanadium (25%), Molybdenum (15%): This composition describes a titanium alloy, not stainless steel.

Stainless steel is primarily an iron-based alloy with chromium as the essential element for corrosion resistance. Nickel is often added for improved properties.

Answer:

C. 316 has added molybdenum, enhancing corrosion resistance.   

The primary difference between stainless steel grades 304 and 316 lies in the addition of molybdenum to 316. This element significantly improves the steel's resistance to corrosion, particularly in environments with high chloride content, such as marine applications.