X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Received: from fed1rmmtao102.cox.net ([68.230.241.44] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1874223 for flyrotary@lancaironline.net; Wed, 28 Feb 2007 12:35:58 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.44; envelope-from=dale.r@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao102.cox.net (InterMail vM.7.05.02.00 201-2174-114-20060621) with ESMTP id <20070228173506.PXWL2670.fed1rmmtao102.cox.net@fed1rmimpo02.cox.net> for ; Wed, 28 Feb 2007 12:35:06 -0500 Received: from [192.168.1.100] ([68.2.134.48]) by fed1rmimpo02.cox.net with bizsmtp id V5b51W00j12ovmC0000000; Wed, 28 Feb 2007 12:35:05 -0500 Message-ID: <45E5BD39.9080805@cox.net> Date: Wed, 28 Feb 2007 10:34:49 -0700 From: Dale Rogers Reply-To: dale.r@cox.net User-Agent: Thunderbird 1.5.0.9 (Windows/20061207) MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: engine mount 4130 vs 304 SS References: In-Reply-To: Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit I should also have mentioned that if I were making something from stainless that had to be welded together, I'd choose the low-carbon version of 304 - 304L. It has less need of the post-weld treatments that plain 304 needs (fewer carbon crystals to precipitate out). Then again, 304L may be significantly more expensive than plain 304 in your market. Dale R.

Rusty, The main strength difference between 4130 and SS304 (aka 30304) is that 4130 can be heat-treated, 304 cannot. Then again, 4130 used in airframe constrution is almost always in "normal" state, so the UTS values aren't terribly far apart: ~75K psi for 304 and ~100K psi for 4130. Yield strength is a different matter. 304 is ~29K psi vs 50K psi for 304. If 29K is enough to do the job, then there are a lot of good reasons to use SS. If you are going to do a lot of drilling on 304 (or 316, which is nearly the same, except slightly better salt corrosion resistance) get some M42 (cobalt) bits. 304 is hard on tooling. (Go ahead, ask me how I know ...) Dale R. COZY MkIV #1254
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