Material US Standard A286
Material US Standard A286
(OP)
We are using the A286 screws in Jetfoil repairing. Now we are going to look for substitution. We just have the material chemical composition and physical properties. Any material specialist can tell me the tips in process of machining, HOW can we check the quality in a easy way after machining?
Thank you!!
Jetfoil repairing
Thank you!!
Jetfoil repairing





RE: Material US Standard A286
RE: Material US Standard A286
We are going to order the "SAME" A286 material (Chinese Standard GH2132) screws from China but we are worrying about the quality. So we are looking for a EASY "method" to check the quality.
Another issue is the machining process e.g. heat treatment or machining first. What is the correct process? Any reliable (manufacturer) with reasonable price recommend?
Thank you!
Ricky
RE: Material US Standard A286
If your screws are to Aerospace standards then they will have to be headed, heat-treated, machined and thread-rolled in that order. If parts are to industrial specs, these may allow machined parts which is normally carried out in solution state before age heat treatment.
RE: Material US Standard A286
There are a number of things that can be done to ensure good quality fasteners. First, require that raw material meets specifications like SAE AMS5726 or ASTM A 453. These standards have requirements for more than just the chemical composition and mechanical properties. Next, the manufacturer should routinely check for quality, both non-destructively and destructively. Non-destructive methods include visual examination using dye penetrant testing or magnetic particle inspection, as well as eddy current testing. The latter is usually part of a 100% inspection system, such as those provided by Mectron (http://www.mectron.net/mectron.html).
Destructive testing involves mechanical testing for yield and tensile strength, wedge testing for head to shank integrity, and fatigue testing. Military and aerospace fastener standards usually require fatigue testing, whereas industry standards usually do not. Other destructive tests involve cross-sectioning the parts to observe for defects (cracks/laps/etc. in threads, folds in the underhead fillet), observe the microstructure (grain size, deformation due to forming and rolling), and find heat treating defects (alloy depletion, intergranular oxidation). Two excellent articles on this subject were published in Structure 30, 1996, which is the Struers Journal of Materialography. You can obtain it by contacting Struers (http://www.struers.com).
Regarding manufacturing, yates provided the usual sequence for aerospace fasteners. I am not sure that this is the standard process for A 286 fasteners, though. A 286 is a precipitation hardening grade, not a martensitic grade like most steel alloys for fasteners, and as such, the precipitation reaction responds better after strain hardening. I believe that fasteners made from A 286 are made from wire that has already been solution annealed, which is subsequently cold formed to shape. Heads are sometime hot formed instead. The threads are then cold rolled, and then finally the bolts are subjected to a low temperature aging process. Perhaps someone else can confirm or deny this, possibly with reference to a standard.
RE: Material US Standard A286
Alternatively, shank and to-be-rolled diameter may, if tolerances allow, be produced by extrusion of the blank through a die, thus introducing cold work into the blank rather than the raw material, before aging.
See specs. AS 7477, 7479
RE: Material US Standard A286
RE: Material US Standard A286
Thanks for the additional information. I'll see if I can't track down a copy of the AS specs.