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Message-ID: <617005.39245.qm@web83903.mail.sp1.yahoo.com>
References: <list-4651355@logan.com>
Date: Wed, 22 Dec 2010 13:10:24 -0800 (PST)
From: Kelly Troyer <keltro@att.net>
Subject: Re: 13B Turbo Manifold
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-4651355@logan.com>
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Ernest you make my head hurt !!...............Now I have to be a =0A"Metall=
urgist"...............<:)=0A=A0=0AKelly Troyer=0A"DYKE DELTA JD2" (Eventual=
ly)=0A"13B ROTARY"_ Engine=0A"RWS"_RD1C/EC2/EM2=0A"MISTRAL"_Backplate/Oil M=
anifold=0A"TURBONETICS"_TO4E50 Turbo=0A=0A=0A=0A=0A________________________=
________=0AFrom: Ernest Christley <echristley@att.net>=0ATo: Rotary motors =
in aircraft <flyrotary@lancaironline.net>=0ASent: Wed, December 22, 2010 2:=
35:58 PM=0ASubject: [FlyRotary] Re: 13B Turbo Manifold=0A=0AKelly Troyer wr=
ote:=0A> Ernest,=0A>=A0 =A0 =A0 Not sure what you mean by "Welds not cleane=
d up"...........All I see on =0A>these "TIG" welds is=0A> a slight discolor=
ation at the edge of the weld bead caused by the arc heat..=0A=0AThe first =
link of a Google search on "stainless steel welding corrosion" was =0Ahttp:=
//www.mcnallyinstitute.com/04-html/4-1.html=0A=0AFrom that site:=0A=0AINTER=
GRANULAR CORROSION=0A=0AAll austenitic stainless steels (the 300 series, th=
e types that "work harden") =0Acontain a small amount of carbon in solution=
 in the austenite. Carbon is =0Aprecipitated out at the grain boundaries, o=
f the steel, in the temperature range =0Aof 1050=B0 F. (565=B0 C) to 1600=
=B0 F. (870=B0 C.). This is a typical temperature range =0Aduring the weldi=
ng of stainless steel.=0A=0AThis carbon combines with the chrome in the sta=
inless steel to form chromium =0Acarbide, starving the adjacent areas of th=
e chrome they need for corrosion =0Aprotection. In the presence of some str=
ong corrosives an electrochemical action =0Ais initiated between the chrome=
 rich and chrome poor areas with the areas low in =0Achrome becoming attack=
ed. The grain boundaries are then dissolved and become non =0Aexistent. The=
re are three ways to combat this:=0A=0A=A0 =A0 * Anneal the stainless after=
 it has been heated in this sensitive range. =0AThis means bringing it up t=
o the proper annealing temperature and then quickly =0Acooling it down thro=
ugh the sensitive temperature range to prevent the carbides =0Afrom forming=
.=0A=A0 =A0 * When possible use low carbon content stainless if you intend =
to do any =0Awelding on it. A carbon content of less than 0.3% will not pre=
cipitate into a =0Acontinuous film of chrome carbide at the grain boundarie=
s. 316L is as good =0Aexample of a low carbon stainless steel.=0A=A0 =A0 * =
Alloy the metal with a strong carbide former. The best is columbium, but =
=0Asometimes titanium is used. The carbon will now form columbium carbide r=
ather =0Athan going after the chrome to form chrome carbide. The material i=
s now said to =0Abe "stabilized"=0A=0AThey could have used a filler that ma=
de post treatment unnecessary, or they =0Acould have annealed it.=A0 The li=
nk you gave says it is made of T304.=A0 Depending =0Aon which T304, the car=
bon ranges from .03 to .08%, so it may not be an issue at =0Aall.=0A=0A=0A-=
-=0AHomepage:=A0 http://www.flyrotary.com/=0AArchive and UnSub:=A0 http://m=
ail.lancaironline.net:81/lists/flyrotary/List.html=0A
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<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></he=
ad><body><div style=3D"font-family:arial, helvetica, sans-serif;font-size:1=
2pt"><DIV></DIV>=0A<DIV>Ernest you make my head hurt !!...............Now I=
 have to be a "Metallurgist"...............&lt;:)<BR>&nbsp;</DIV>=0A<P>Kell=
y Troyer<BR><STRONG><FONT size=3D4>"DYKE DELTA JD2"</FONT> <FONT size=3D1>(=
Eventually)</FONT></STRONG></P>=0A<P>"13B ROTARY"_ Engine<BR>"RWS"_RD1C/EC2=
/EM2<BR>"MISTRAL"_Backplate/Oil Manifold</P>=0A<P>"TURBONETICS"_TO4E50 Turb=
o</P>=0A<DIV><BR></DIV>=0A<DIV style=3D"FONT-FAMILY: arial, helvetica, sans=
-serif; FONT-SIZE: 12pt"><BR>=0A<DIV style=3D"FONT-FAMILY: times new roman,=
 new york, times, serif; FONT-SIZE: 10pt"><FONT size=3D2 face=3DTahoma>=0A<=
HR SIZE=3D1>=0A<B><SPAN style=3D"FONT-WEIGHT: bold">From:</SPAN></B> Ernest=
 Christley &lt;echristley@att.net&gt;<BR><B><SPAN style=3D"FONT-WEIGHT: bol=
d">To:</SPAN></B> Rotary motors in aircraft &lt;flyrotary@lancaironline.net=
&gt;<BR><B><SPAN style=3D"FONT-WEIGHT: bold">Sent:</SPAN></B> Wed, December=
 22, 2010 2:35:58 PM<BR><B><SPAN style=3D"FONT-WEIGHT: bold">Subject:</SPAN=
></B> [FlyRotary] Re: 13B Turbo Manifold<BR></FONT><BR>Kelly Troyer wrote:<=
BR>&gt; Ernest,<BR>&gt;&nbsp; &nbsp; &nbsp; Not sure what you mean by "Weld=
s not cleaned up"...........All I see on these "TIG" welds is<BR>&gt; a sli=
ght discoloration at the edge of the weld bead caused by the arc heat..<BR>=
<BR>The first link of a Google search on "stainless steel welding corrosion=
" was http://www.mcnallyinstitute.com/04-html/4-1.html<BR><BR>From that sit=
e:<BR><BR>INTERGRANULAR CORROSION<BR><BR>All austenitic stainless steels (t=
he 300 series, the types that "work harden") contain a small amount of carb=
on in solution
 in the austenite. Carbon is precipitated out at the grain boundaries, of t=
he steel, in the temperature range of 1050=B0 F. (565=B0 C) to 1600=B0 F. (=
870=B0 C.). This is a typical temperature range during the welding of stain=
less steel.<BR><BR>This carbon combines with the chrome in the stainless st=
eel to form chromium carbide, starving the adjacent areas of the chrome the=
y need for corrosion protection. In the presence of some strong corrosives =
an electrochemical action is initiated between the chrome rich and chrome p=
oor areas with the areas low in chrome becoming attacked. The grain boundar=
ies are then dissolved and become non existent. There are three ways to com=
bat this:<BR><BR>&nbsp; &nbsp; * Anneal the stainless after it has been hea=
ted in this sensitive range. This means bringing it up to the proper anneal=
ing temperature and then quickly cooling it down through the sensitive temp=
erature range to prevent the carbides from forming.<BR>&nbsp; &nbsp; *
 When possible use low carbon content stainless if you intend to do any wel=
ding on it. A carbon content of less than 0.3% will not precipitate into a =
continuous film of chrome carbide at the grain boundaries. 316L is as good =
example of a low carbon stainless steel.<BR>&nbsp; &nbsp; * Alloy the metal=
 with a strong carbide former. The best is columbium, but sometimes titaniu=
m is used. The carbon will now form columbium carbide rather than going aft=
er the chrome to form chrome carbide. The material is now said to be "stabi=
lized"<BR><BR>They could have used a filler that made post treatment unnece=
ssary, or they could have annealed it.&nbsp; The link you gave says it is m=
ade of T304.&nbsp; Depending on which T304, the carbon ranges from .03 to .=
08%, so it may not be an issue at all.<BR><BR><BR>--<BR>Homepage:&nbsp; htt=
p://www.flyrotary.com/<BR>Archive and UnSub:&nbsp; http://mail.lancaironlin=
e.net:81/lists/flyrotary/List.html<BR></DIV></DIV></div></body></html>
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