X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from m12.lax.untd.com ([64.136.30.75] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with SMTP id 1317394 for flyrotary@lancaironline.net; Wed, 26 Jul 2006 17:58:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.30.75; envelope-from=alwick@juno.com Received: from m12.lax.untd.com (localhost [127.0.0.1]) by m12.lax.untd.com with SMTP id AABCNR3LMAAVG8Y2 for (sender ); Wed, 26 Jul 2006 14:57:31 -0700 (PDT) X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkEiDtZSBgIavCLwei2dfJ9GkACw8cHbH0g== Received: (from alwick@juno.com) by m12.lax.untd.com (jqueuemail) id LV84G8T7; Wed, 26 Jul 2006 14:56:42 PDT To: flyrotary@lancaironline.net Date: Wed, 26 Jul 2006 14:56:09 -0700 Subject: Re: [FlyRotary] Inconel Message-ID: <20060726.145617.1308.38.alwick@juno.com> X-Mailer: Juno 5.0.33 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=--__JNP_000_42c2.014f.12d8 X-Juno-Line-Breaks: 8-6,11,16,20,27-36,38,43-44,49-61,62-32767 From: al p wick X-ContentStamp: 8:4:2054227172 X-MAIL-INFO:2a414110fd1951c9e4ad2910802901e144c48429d524a4ddfdd584c4d5f0d555cd49f494416d10b910c5fd640111a064c919e549c19535890995b5b5313d9109a081004070e90d004081300c1111dd21a90c95ed95899495c1f5842039b539919d1d8d95413ddd1df4b121313da4f41dd16dc46da48425ddc441e9c5d041 X-UNTD-Peer-Info: 127.0.0.1|localhost|m12.lax.untd.com|alwick@juno.com This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ----__JNP_000_42c2.014f.12d8 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit I have a lot of experience with failure analysis. Used to do it with GM, Ford, other warranty returns. One of my favorite experiences was solving a million $ warranty issue on a tubing product. Although I'm not expert in this area, I'd sure encourage considering other factors, other solutions. In particular I'd encourage use of strobe lamp. Take cowl off, fire up engine, use strobe. (yes, it's dangerous with prop on) You will suddenly have appreciation for the forces involved. You should be able to predict failure points with this test. Tack together the broken one to see what I mean. The exhaust will turn into a sine shape at certain rpm. You will see huge amount of movement on the busted one. Make a new design, compare movement to predict how long it will last. A very minor design change can greatly improve how much movement occurs. I'm not sure this is applicable to you guys, but my exhaust design has slip fit of two pipes instead of welding. It works phenomenal. I've had conversation with other guys who welded instead and had failures. Same exact application. So my exhaust floats in relation to the header. I just attach a small bracket to the floating portion to prevent if from blowing off. Truthfully, I never expected it to work, but it has quite well. I might have pic if verbal description not adequate. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html On Wed, 26 Jul 2006 14:22:34 -0700 "Al Gietzen" writes: I say it is brittle because it has failed twice and both times quite spectacularly. Not only did the inconel fail in the area adjacent to the welds but spider cracks formed flowing out of the main cracks and into the surrounding area. It looked like glass might look if you punch a hole in it (i.e. not tempered glass!). That is interesting. Sounds like ‘stress corrosion’ cracking; which is the reason to use inconel vs other SS alloys at these temps. Almost makes me wonder whether the welder picked up the wrong material when he made the parts; or at least didn’t give it any annealing heat treatment after welding. http://www.corrosion-doctors.org/Forms/scc.htm Al -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ----__JNP_000_42c2.014f.12d8 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: quoted-printable
I have a lot of experience with failure analysis. Used to do it with = GM,=20 Ford, other warranty returns. One of my favorite experiences was solving a= =20 million $ warranty issue on a tubing product. Although I'm not expert in = this=20 area, I'd sure encourage considering other factors, other solutions.
In particular I'd encourage use of strobe lamp. Take cowl off, fire up= =20 engine, use strobe. (yes, it's dangerous with prop on) You will suddenly = have=20 appreciation for the forces involved. You should be able to predict failure= =20 points with this test. Tack together the broken one to see what I mean= .=20
The exhaust will turn into a sine shape at certain rpm. You will see = huge=20 amount of movement on the busted one. Make a new design, compare movement = to=20 predict how long it will last. A very minor design change can greatly = improve=20 how much movement occurs.
I'm not sure this is applicable to you guys, but my exhaust design has= slip=20 fit of two pipes instead of welding. It works phenomenal. I've had = conversation=20 with other guys who welded instead and had failures. Same exact application= . So=20 my exhaust floats in relation to the header. I just attach a small bracket = to=20 the floating portion to prevent if from blowing off. Truthfully, I never=20 expected it to work, but it has quite well. I might have pic if verbal=20 description not adequate.
 

-al wick
Artificial intelligence in cockpit, Cozy IV powered by= =20 stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland,=20 Oregon
Prop construct, Subaru install, Risk assessment, Glass panel = design=20 info:
http:= //www.maddyhome.com/canardpages/pages/alwick/index.html
 
On Wed, 26 Jul 2006 14:22:34 -0700 "Al Gietzen" <ALVentures@cox.net> writes:

I say it is brittle because it = has failed=20 twice and both times quite spectacularly. Not only did the inconel fail = in the=20 area adjacent to the welds but spider cracks formed flowing out of the = main=20 cracks and into the surrounding area. It looked like glass might look if = you=20 punch a hole in it (i.e. not tempered glass!).

 

That is=20 interesting.  Sounds like ‘stress corrosion’ cracking; = which is the=20 reason to use inconel vs other SS alloys at these temps.  Almost = makes me=20 wonder whether the welder picked up the wrong material when he made the = parts;=20 or at least didn’t give it any annealing heat treatment after=20 welding.

 

http://www.= corrosion-doctors.org/Forms/scc.htm

 

Al

 

 

 

-al wick
Artificial intelligence in= =20 cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on=20 engine/airframe from Portland, Oregon
Prop construct, Subaru install, = Risk=20 assessment, Glass panel design=20 info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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