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On Sun, 1 Feb 2009 12:13:59 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:
"Charles Vincent" wrote in message . .. Stealth Pilot wrote: On Tue, 27 Jan 2009 16:47:51 -0500, "Morgans" wrote: "Stealth Pilot" wrote hydrogen embrittlement was a big bogey man in home castings but it is easily understood and conquered. OK, I understand hydrogen embrittlement is a "bad thing" but my question is, where does it come from, start, or what do you do to prevent it from happening in the first place. I'm not an industrial chemist. this comes from watching what happens in my castings and reading some of the references mentioned. What you are describing is not Hydrogen Embrittlement. Hydrogen Embrittlement is usually more of an issue for high carbon steels I believe, though it effects aluminum as well. You can find information on it under the heading of stress corrosion cracking and it is more of an environmental issue than casting, as it is a problem for forgings and weldments as well. It is the mechanism of failure I am pretty sure for the old VW cases, as magnesium alloys are very susceptable to SCC. Your description of the problem of the casting problem though is spot on, if misnamed. Here is a good link on this and other alumminum casting issues: http://www.keytometals.com/Article83.htm Charles Actually it highlights his misunderstanding of the process. In an effort to look like he knows something about casting, he began searching the internet and found reams of confusing material discussing hydrogen embrittlement, and confused it with hydrogen absorption. the references I use are aspin and ammin. I occasionally search the net to see if anyone has a technique that is better than I'm using but so far they confirm that my teacher was a master of the art. Nice link, by the way, it at least begins to discuss the difficulties of pouring quality molten aluminum, especially in low volumes if you read between the lines. Saying you are going to pour a quality casting from melting old pistons, in a steel pot, with a propane yard burner - is much like saying you are going to grind you own crankshaft with a modified wood lathe and a hand grinder. what baloney. I use salamander or gold refining crucibles. I use a waste oil burner of the "major type S" pattern. in fact when a casting is larger than my crucible can handle I offload the work to a commercial foundry. they use waterglass and resin moulding techniques normally but also use greensand. their greensand techniques vary from mine in the use of machine aids, other than that we talk and do the same things. you are so full of it your eyes are brown. Stealth Pilot |
#2
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![]() "Stealth Pilot" wrote in message news ![]() On Sun, 1 Feb 2009 12:13:59 -0600, "Maxwell" #$$9#@%%%.^^^ wrote: "Charles Vincent" wrote in message .. . Stealth Pilot wrote: On Tue, 27 Jan 2009 16:47:51 -0500, "Morgans" wrote: "Stealth Pilot" wrote hydrogen embrittlement was a big bogey man in home castings but it is easily understood and conquered. OK, I understand hydrogen embrittlement is a "bad thing" but my question is, where does it come from, start, or what do you do to prevent it from happening in the first place. I'm not an industrial chemist. this comes from watching what happens in my castings and reading some of the references mentioned. What you are describing is not Hydrogen Embrittlement. Hydrogen Embrittlement is usually more of an issue for high carbon steels I believe, though it effects aluminum as well. You can find information on it under the heading of stress corrosion cracking and it is more of an environmental issue than casting, as it is a problem for forgings and weldments as well. It is the mechanism of failure I am pretty sure for the old VW cases, as magnesium alloys are very susceptable to SCC. Your description of the problem of the casting problem though is spot on, if misnamed. Here is a good link on this and other alumminum casting issues: http://www.keytometals.com/Article83.htm Charles Actually it highlights his misunderstanding of the process. In an effort to look like he knows something about casting, he began searching the internet and found reams of confusing material discussing hydrogen embrittlement, and confused it with hydrogen absorption. the references I use are aspin and ammin. I occasionally search the net to see if anyone has a technique that is better than I'm using but so far they confirm that my teacher was a master of the art. Nice link, by the way, it at least begins to discuss the difficulties of pouring quality molten aluminum, especially in low volumes if you read between the lines. Saying you are going to pour a quality casting from melting old pistons, in a steel pot, with a propane yard burner - is much like saying you are going to grind you own crankshaft with a modified wood lathe and a hand grinder. what baloney. I use salamander or gold refining crucibles. I use a waste oil burner of the "major type S" pattern. in fact when a casting is larger than my crucible can handle I offload the work to a commercial foundry. they use waterglass and resin moulding techniques normally but also use greensand. their greensand techniques vary from mine in the use of machine aids, other than that we talk and do the same things. you are so full of it your eyes are brown. Stealth Pilot Photos? Photos? Still waiting. |
#3
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![]() "Stealth Pilot" wrote you are so full of it your eyes are brown. Wrestling with Max is like wrestling with a pig. You both get dirty, and the pig enjoys it. -- Jim in NC |
#4
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![]() "Morgans" wrote in message ... "Stealth Pilot" wrote you are so full of it your eyes are brown. Wrestling with Max is like wrestling with a pig. You both get dirty, and the pig enjoys it. -- Jim in NC Not true. I have never attacked anyone that didn't throw the first punch, including you. |
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