X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao07.cox.net ([68.230.241.32] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTP id 1317345 for flyrotary@lancaironline.net; Wed, 26 Jul 2006 17:23:15 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.32; envelope-from=ALVentures@cox.net Received: from BigAl ([72.192.132.90]) by fed1rmmtao07.cox.net (InterMail vM.6.01.06.01 201-2131-130-101-20060113) with ESMTP id <20060726212228.YRGR11027.fed1rmmtao07.cox.net@BigAl> for ; Wed, 26 Jul 2006 17:22:28 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: Inconel Date: Wed, 26 Jul 2006 14:22:34 -0700 Message-ID: <000001c6b0f9$9cc2df80$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C6B0BE.F0640780" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C6B0BE.F0640780 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 ------=_NextPart_000_0001_01C6B0BE.F0640780 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

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.corros= ion-doctors.org/Forms/scc.htm

 

Al

 

 

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