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Date: Sat, 01 Jun 2013 17:40:03 -0400
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Subject: Re: [LML] Temperature effect on aluminum
References: <list-6301394@logan.com>
From: Paul Miller <pjdmiller@gmail.com>
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Very interesting graph but duration at temp is the problem.   I will make a f=
ew assumptions from this graph and toss them out:
1. Minor time excursions into the higher temps will not affect strength.   O=
perating at 425 through TBO would affect strength appreciably but 15 minutes=
 is not going to make any difference.
2.  We must have safety margins built in even at max operating temp for thes=
e engines so we must be operating way down on that graph.
3. Fatigue strength is probably far less than tensile stress in the graph so=
 we must have even a larger safety margin for fatigue protection and be furt=
her down the graph in normal ops.
4. Cylinder heads likely have both tensile and compressive loads.  Tensile l=
oads may be an issue or maybe high temps near the exhaust valve is the limit=
ing issue with temps.
5. Rebuilding with previously flown cylinder heads could leave you with dimi=
nished protection in strength unless you know the temp history.

Thanks for that graph Fred.

Paul

On 2013-05-31, at 23:04, "Frederick Moreno" <frederickmoreno@bigpond.com> wr=
ote:

>=20
> <SENDER_EMAILfrederickmoreno@bigpond@@com.png>
> Paul wrote:
> =20
> "Colyn: I just re-read that article, Busch states:
>=20
>  (The head's tensile strength is reduced to 50% of its room-temperature va=
lue at a CHT of 400F, and to about 33% at 500F.)
>=20
> I don't see that supported in any literature studying the properties of st=
eel versus temperature."
> =20
> The cylinder heads are ALUMINUM and the cylinders are steel.  Attached cha=
rt shows that the 1000 hour strength of 356 aluminum alloy heads south rapid=
ly as exposure temperature exceeds 300F.=20
> =20
> Fred
> <cz_Heat_Effect_on_Aluminum.JPG>
> --
> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.htm=
l

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div>Very interesting graph but duration at=
 temp is the problem. &nbsp; I will make a few assumptions from this graph a=
nd toss them out:</div><div>1. Minor time excursions into the higher temps w=
ill not affect strength. &nbsp; Operating at 425 through TBO would affect st=
rength appreciably but 15 minutes is not going to make any difference.</div>=
<div>2. &nbsp;We must have safety margins built in even at max operating tem=
p for these engines so we must be operating way down on that graph.</div><di=
v>3. Fatigue strength is probably far less than tensile stress in the graph s=
o we must have even a larger safety margin for fatigue protection and be fur=
ther down the graph in normal ops.</div><div>4. Cylinder heads likely have b=
oth tensile and compressive loads. &nbsp;Tensile loads may be an issue or ma=
ybe high temps near the exhaust valve is the limiting issue with temps.</div=
><div>5. Rebuilding with previously flown cylinder heads could leave you wit=
h diminished protection in strength unless you know the temp history.</div><=
div><br></div><div>Thanks for that graph Fred.</div><div><br>Paul</div><div>=
<br>On 2013-05-31, at 23:04, "Frederick Moreno" &lt;<a href=3D"mailto:freder=
ickmoreno@bigpond.com">frederickmoreno@bigpond.com</a>&gt; wrote:<br><br></d=
iv><blockquote type=3D"cite"><div>
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<div style=3D"POSITION: absolute; WIDTH: 50px; HEIGHT: 50px; LEFT: 0px" id=3D=
"INCREDIPICTURE">&lt;SENDER_EMAILfrederickmoreno@bigpond@@com.png&gt;</div>
<div style=3D"PADDING-LEFT: 80px" id=3D"INCREDI_TEXT_AREA">
<div>Paul wrote:</div>
<div>&nbsp;</div>
<div>"Colyn: I just re-read that article, Busch states:=20
<div><br></div>
<div><span style=3D"TEXT-ALIGN: left; LINE-HEIGHT: 16px; BACKGROUND-COLOR: r=
gb(255,255,255); FONT-FAMILY: Verdana, Arial, sans-serif; COLOR: rgb(51,51,5=
1); FONT-SIZE: 13px">&nbsp;(The head's tensile strength is reduced to 50% of=
 its room-temperature value at a CHT of 400F, and to about 33% at 500F.)</sp=
an></div>
<div>
<div style=3D"TEXT-ALIGN: left"><font color=3D"#333333" face=3D"Verdana, Ari=
al, sans-serif"><span style=3D"LINE-HEIGHT: 16px; FONT-SIZE: 13px"><br></spa=
n></font></div>
<div style=3D"TEXT-ALIGN: left"><font color=3D"#333333" face=3D"Verdana, Ari=
al, sans-serif"><span style=3D"LINE-HEIGHT: 16px; FONT-SIZE: 13px">I don't s=
ee that supported in any literature studying the properties of steel versus t=
emperature."</span></font></div>
<div style=3D"TEXT-ALIGN: left"><font color=3D"#333333" face=3D"Verdana, Ari=
al, sans-serif"><span style=3D"LINE-HEIGHT: 16px; FONT-SIZE: 13px"></span></=
font>&nbsp;</div>
<div style=3D"TEXT-ALIGN: left"><font color=3D"#333333" face=3D"Verdana, Ari=
al, sans-serif"><span style=3D"LINE-HEIGHT: 16px; FONT-SIZE: 13px">The cylin=
der heads are ALUMINUM and the cylinders are steel.&nbsp; Attached chart sho=
ws that the 1000 hour strength of 356 aluminum alloy heads south rapidly as e=
xposure temperature exceeds 300F.&nbsp; </span></font></div>
<div style=3D"TEXT-ALIGN: left"><font color=3D"#333333" face=3D"Verdana, Ari=
al, sans-serif"><span style=3D"LINE-HEIGHT: 16px; FONT-SIZE: 13px"></span></=
font>&nbsp;</div>
<div style=3D"TEXT-ALIGN: left"><font color=3D"#333333" face=3D"Verdana, Ari=
al, sans-serif"><span style=3D"LINE-HEIGHT: 16px; FONT-SIZE: 13px">Fred</spa=
n></font></div></div></div></div></td></tr>
<tr>
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<td width=3D"100%"></td>
<td id=3D"INCREDISOUND" valign=3D"bottom" align=3D"middle"></td></tr></tbody=
></table></td></tr></tbody></table></div></blockquote><blockquote type=3D"ci=
te"><div>&lt;cz_Heat_Effect_on_Aluminum.JPG&gt;</div></blockquote><blockquot=
e type=3D"cite"><div><span>--</span><br><span>For archives and unsub <a href=
=3D"http://mail.lancaironline.net:81/lists/lml/List.html">http://mail.lancai=
ronline.net:81/lists/lml/List.html</a></span><br></div></blockquote></body><=
/html>=

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