Fastener Materials & Manufacturing Flashcards

Titanium fasteners are most commonly specified in aerospace applications primarily due to their:

Answer: High strength-to-weight ratio and excellent corrosion resistance

Titanium offers a very high strength-to-weight ratio and outstanding corrosion resistance, making it ideal for weight-critical aerospace applications.

What is the primary purpose of quenching during fastener heat treatment?

Answer: Rapidly cool the steel to form martensite and increase hardness

Quenching rapidly cools austenized steel (typically in oil or water) to trap carbon in the lattice and form hard martensite.

Which thread rolling method uses two flat dies, one stationary and one reciprocating?

Answer: Flat die rolling

Flat die rolling passes the blank between one fixed and one moving flat die to form threads through cold working.

A fastener marked 'A2-70' follows which standard and what does '70' indicate?

Answer: ISO standard; 700 MPa minimum tensile strength

A2-70 is an ISO designation where A2 = austenitic stainless steel Type 304 and 70 = 700 MPa minimum tensile strength.

What type of corrosion occurs between a steel fastener and an aluminum structure in a moist environment?

Answer: Galvanic corrosion

Galvanic corrosion occurs when dissimilar metals (steel and aluminum) are in electrical contact in the presence of an electrolyte, causing the more anodic metal to corrode.

Which mechanical property is measured by the Charpy impact test?

Answer: Impact toughness

The Charpy test measures impact toughness by swinging a pendulum to break a notched specimen and measuring the absorbed energy.

What is the function of tempering after quench hardening of fastener steel?

Answer: Reduce brittleness while retaining most of the hardness gained from quenching

Tempering reheats quenched martensite to a lower temperature, reducing brittleness and internal stresses while maintaining most of the hardness.