Metallurgy
The following material is intended to provide a brief overview of the metallurgical considerations that, daily, influence the design and production of the most reliable fasteners in motorsports. It is hoped that a simple understanding of the knowledge and commitment required to produce this reliability will make your future fastener decisions much, much easier.
Metallurgy for the Non-engineer
BY RUSSELL SHERMAN, PE
The original article has been split into the following sections:
Fundamentals
- What is grain size and how important is it?
- How do you get toughness vs. brittleness?
- Define Rockwell as we use it. Why do we use the C scale?
- What is "micro hardness?"
- How does modulus of elasticity refer to our products?
Materials & Alloys
- What are metal carbides and what is their significance?
- What exactly is chromium?
- What exactly is A286? And to what is it compared?
- What is the difference between 4130 and 8740 chrome moly?
- What exactly is ARP2000 and how does it compare to 8740 and 4340?
- How does L19 compare to ARP2000?
- What is AMS5844? And how does it compare to AMS5842E?
Atomic Structure
- What does it mean when a broken part looks crystallized?
- Define "precipitation hardening" and "phase change."
- What does a "face centered cubic" (fcc) atom arrangement look like? How many atoms?
- How does a "body center cubic" (bcc) atom look? How many atoms?
- What does a "stainless steel" atom arrangement look like? How many atoms?
- How do the space lattice or crystal structures appear?
Manufacturing
- What are the metallurgical ramifications of "cold heading" vs. "hot heading"?
- What is the difference between the usage of "bar" material vs. "wire"?
- Define "Power Dump."
Standards & Testing
- Provide a brief overview of the metallurgy required to produce AN, AMS & other Aerospace type fasteners.
- What is moisture tolerance and how or where is it important?
- How do the various standards compare to each other with regard to fasteners? Where are the standards?
Failure Analysis
- What metallurgical issues cause common failures?