AUDI Material Selection & Properties 3

Question 1

Which heat treatment process is used to increase the hardness and wear resistance of Audi crankshaft bearing journals?

Accepted Answer

Induction hardening

Answer

Induction hardening selectively heats only the bearing journal surface, creating a hard martensitic layer while leaving the core tough and ductile.

Question 2

Audi uses magnesium alloy for certain engine components such as the crankcase. What is the biggest material handling concern with magnesium during machining?

Accepted Answer

Magnesium chips and dust are highly flammable and can ignite spontaneously

Answer

Magnesium swarf and fine dust are extremely flammable and can ignite spontaneously, requiring dry-chemical fire suppression and strict housekeeping procedures.

Question 3

What distinguishes a thermoplastic from a thermoset polymer used in Audi interior and exterior components?

Accepted Answer

Thermoplastics can be remelted and reshaped; thermosets cannot

Answer

Thermoplastics soften and can be reprocessed when heated, while thermosets undergo irreversible cross-linking during curing and cannot be remelted.

Question 4

Audi specifies titanium fasteners in certain high-performance applications. Compared to steel fasteners of the same size, titanium offers:

Accepted Answer

Approximately 45% lower density with comparable tensile strength

Answer

Titanium's density is about 4.5 g/cm³ versus steel's ~7.8 g/cm³, roughly 45% lighter, while high-grade titanium alloys match or exceed many steel grades in tensile strength.

Question 5

Which rubber compound is most suitable for Audi's turbocharger intake hoses that must withstand sustained temperatures up to 200°C?

Accepted Answer

Silicone rubber (VMQ)

Answer

Silicone rubber retains flexibility and sealing properties across a wide temperature range from -60°C to over 200°C, making it ideal for high-temperature turbo hoses.

(AUDI) Audi Certified Mechanic Practice Test

(AUDI) Audi Certified Mechanic Practice Test

AUDI Material Selection & Properties 3