What's the boron content of 10B30?
I note that ISO 898-1 limits the boron content of material used to fabricate property class 10.9 fasteners to .003% (.005% provided that "non-effective boron is controlled by addition of titanium and/or aluminum").
Does "equivalency" require grademarking (marking with "10.9") or representing/selling the parts as meeting Grade 10.9? If so, manufacturing bolts to anything less than the full requirments of the ISO standard is a SEROIUS crime punishable by both civil and criminal penalties per the Fastener...
Lurchalot:
Re-read midsidenode's original post:
A delayed failure mecahanism is at work here, most likely hydrogen embrittlement as suggested above. This is not a "simple" overtorque failure.
From the FRR Briefing Transcript:
QUESTIONER: Traci Watson, USA Today, for Wayne Hale.
First, a clarification. When you talked about the bolts that had only two-thirds of the thread or one-and-a-half threads engaged, was that on the KU antenna, or was that somewhere else? I missed that.
MR...
Based on the available information, I wouldn’t personally characterize anything about this situation as "perfectly adequate" (an oxymoron?).
While it was apparently "adequate" for 25 flights (based solely on the absence of a catastrophic failure), what about the 26th? The "it worked last time"...
Wayne Hale (http://www.nasa.gov/centers/kennedy/about/biographies/hale.html), excerpted from the Post Flight Readiness Review Briefing Transcript (http://www.nasa.gov/pdf/154909main_postFRRtranscript%20_2.pdf);
"Some 25 or 30 years ago, a mistake was made in the design of this particular...
Like MMPDS-02, ESDU00932 isn't free either: http://engineers.ihs.com/engineering/newsletters/esdu/esdu-issue08-06.jsp and http://www.esdu.com/cgi-bin/ps.pl?sess=unlicensed_1060801190352snh&t=ser&p=mmdh
Couple of reason why not:
"Normal" bolts are thread rolled, for cost and other reasons. The asymmetrical buttress thread does not lend itself to thread rolling with acceptable tool life or without developing unacceptable defects. "Cut" threads both cost more to make in large quantities and...
