Fastener Materials & Manufacturing Flashcards

Which ASTM specification covers carbon and alloy steel externally threaded metric fasteners?

Answer: ASTM F568M

ASTM F568M covers carbon and alloy steel externally threaded metric fasteners, with property classes analogous to ISO 898-1.

Hydrogen embrittlement in fasteners is most likely to occur during which process?

Answer: Electroplating

Electroplating exposes steel to hydrogen ions in the acid pickling and plating baths, which can diffuse into the steel and cause hydrogen embrittlement.

What is the primary advantage of thread rolling over thread cutting?

Answer: Cold working produces stronger threads with compressive residual stresses

Thread rolling cold-works the material, increasing strength through work hardening and introducing beneficial compressive residual stresses that improve fatigue life.

Monel fasteners are best suited for applications requiring:

Answer: Corrosion resistance in hydrofluoric acid and seawater

Monel (nickel-copper alloy) offers outstanding corrosion resistance in seawater and hydrofluoric acid environments where stainless steel may fail.

Which specification defines property classes for metric steel bolts, screws, and studs (e.g., 8.8, 10.9, 12.9)?

Answer: ISO 898-1

ISO 898-1 defines mechanical and physical properties for metric fasteners using the property class system where the numbers relate to tensile strength and yield ratio.

What defect can result from excessive cold working during fastener forming without intermediate annealing?

Answer: Work hardening leading to cracking

Excessive cold working without annealing causes the material to become too hard and brittle, leading to cracking during subsequent forming operations.

Which surface treatment bakes hydrogen out of electroplated steel fasteners to prevent embrittlement?

Answer: Hydrogen embrittlement relief (baking)

Post-plate baking (typically 375°F for 3–24 hours) drives absorbed hydrogen out of the steel, per ASTM F1941 and similar standards.