Any opinions on residual metal stress?
April 17th, 2013, 11:09 AM
#1
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Any opinions on residual metal stress?
So now the block and heads have been magnafluxed and all appeared well. We'll see what the numbers say. But before anything else happens, is there any value in having the components stress relieved? I understand Mondello offers a vibrational type, but I also read about a cryogenic process. Any opinions on this are really appreciated!
April 18th, 2013, 07:52 AM
#3
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...No, this is an old block with (alleged) 78K. I'm not familiar with the term "seasoning." Would it be along the lines of what happens when one seasons a cast iron skillet? Thanks!
April 18th, 2013, 07:57 AM
#4
"Car"mudgeon
Join Date: Feb 2011
Location: Perry, GA
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Basically it means a used block not new.
It's an engine block that has been used for a few years. The repeated heat cycling of regular use causes the metal of the block to settle, the molecules move into an ordered lattice that is much stronger than the disorganization of a fresh casting. These blocks, most often found at junkyards are prized by hot-rodders and rebuilders because they can handle the stress of extreme performance modifications and engine blueprinting.
It's an engine block that has been used for a few years. The repeated heat cycling of regular use causes the metal of the block to settle, the molecules move into an ordered lattice that is much stronger than the disorganization of a fresh casting. These blocks, most often found at junkyards are prized by hot-rodders and rebuilders because they can handle the stress of extreme performance modifications and engine blueprinting.
April 18th, 2013, 08:46 AM
#5
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Basically it means a used block not new.
It's an engine block that has been used for a few years. The repeated heat cycling of regular use causes the metal of the block to settle, the molecules move into an ordered lattice that is much stronger than the disorganization of a fresh casting. These blocks, most often found at junkyards are prized by hot-rodders and rebuilders because they can handle the stress of extreme performance modifications and engine blueprinting.
It's an engine block that has been used for a few years. The repeated heat cycling of regular use causes the metal of the block to settle, the molecules move into an ordered lattice that is much stronger than the disorganization of a fresh casting. These blocks, most often found at junkyards are prized by hot-rodders and rebuilders because they can handle the stress of extreme performance modifications and engine blueprinting.
Metal doesn't "settle", and molecules don't "move into an ordered lattice". Metallurgically speaking, that is nonsense gibberish.
Give me a metalurgically based statement, and I'll listen.
April 18th, 2013, 09:09 AM
#6
"Car"mudgeon
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That is pure hogwash. That is not any terminology that is used by anyone with any metallurgical knowledge. Except "seasoning" is an informal term used for a heat treatment given to heat treat fixtures to carburize the surfaces before they are cycled in service.
Metal doesn't "settle", and molecules don't "move into an ordered lattice". Metallurgically speaking, that is nonsense gibberish.
Give me a metalurgically based statement, and I'll listen.
Metal doesn't "settle", and molecules don't "move into an ordered lattice". Metallurgically speaking, that is nonsense gibberish.
Give me a metalurgically based statement, and I'll listen.
April 18th, 2013, 10:07 AM
#7
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Proven fact. Anyone that builds and races engines knows this fact. Look it up instead of stalking me and quoting me on every post. You are one more time TROLLING for an argument and or fight. I believe you have lost all aspect of what this forum represents and I would greatly appreciate you exercise the right to STFU. Because you apparently know nothing about "seasoned" engines nor new castings for that matters. Time after time you go out of your way to disprove anything I say instead of contributing to the original post or thread for that matters. In my book you are no better than a certain guy by the name of Andy.
April 18th, 2013, 10:10 AM
#8
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Like I pointed out, there are no facts in what you said, and if you feel it proven, then you can go ahead and provide the proof. Readers deserve to know when something is said that is not true. I have a background in metallurgy and that's why I'm on this thread. Don't flatter yourself to think I have any interest in following you. I'm only interested in the truth.
April 18th, 2013, 10:51 AM
#9
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In my opinion performing cryongenic tempering to a block is very expensive for the benefit you will realize. Some years ago I worked for a company that looked into this process. We provided the vendor with several samples of aluminum and steel to temper. We took the "tempered" samples and non tempered samples to the University of Arkansas Engineering department to test on their lab equipment. Testing performed was tensile, compression and hardness tests. What we discovered is:
1) The yield point of the tempered material increased vs the non tempered material.
2) Ultimate strength was not appreciably changed.
3) Surface hardness on the tempered material improved significantly.
4) The plastic range of the tempered material was "smaller" than the non tempered material. Plastic range is referred to as the area past exceeding yield and just up to failure. What this means is the tempered material had a higher yield stress but exhibited the failure of a brittle material. There was less warning of impending failure once yield was exceeded. Whereas the non tempered material had a lower yield but a more pronounced plastic range (gave plenty of warning before failure).
Cryogenic process is good for rifle barrels, musical instruments and maybe other items but it won't appreciably increase the strength of a cast iron block in my opinion. It will increase the hardness at the surface and slightly below the surface (this is a benefit), it will also make the piece more stable, dimensionably, when subjected to heat.
If these are important benefits to you then it may be worth the $$$. Yes I am aware NASCAR and INDY teams do this to engine components. It has a benefit if you are walking the knifes edge between failure and success. For a street motor....your $$ is better utilized in other ways.
This is my opinion. Others may agree or not, that is your choice.
1) The yield point of the tempered material increased vs the non tempered material.
2) Ultimate strength was not appreciably changed.
3) Surface hardness on the tempered material improved significantly.
4) The plastic range of the tempered material was "smaller" than the non tempered material. Plastic range is referred to as the area past exceeding yield and just up to failure. What this means is the tempered material had a higher yield stress but exhibited the failure of a brittle material. There was less warning of impending failure once yield was exceeded. Whereas the non tempered material had a lower yield but a more pronounced plastic range (gave plenty of warning before failure).
Cryogenic process is good for rifle barrels, musical instruments and maybe other items but it won't appreciably increase the strength of a cast iron block in my opinion. It will increase the hardness at the surface and slightly below the surface (this is a benefit), it will also make the piece more stable, dimensionably, when subjected to heat.
If these are important benefits to you then it may be worth the $$$. Yes I am aware NASCAR and INDY teams do this to engine components. It has a benefit if you are walking the knifes edge between failure and success. For a street motor....your $$ is better utilized in other ways.
This is my opinion. Others may agree or not, that is your choice.
April 18th, 2013, 01:04 PM
#12
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I'll be glad to add my "option" as I have some background in this, too, having taught a college-level, introductory materials science class for more than 20 years.
Nothing will happen to cast iron, microstructurally-speaking, until it is heated to 727 degrees C, the temperature of the iron/iron-carbide eutectoid. That's 1340 degrees F, and no car engine operates anywhere near that temperature. So, as Wmachine says, the repeated heating and cooling that an engine undergoes in use has no effect on its microstructure.
To temper steel requires heating to at least 400 C, which which is about 750 F, so, again, no amount of use as car engine will cause tempering to occur. Only certain steels can be tempered, though, and these are steels that form a microstructure known as "martensite" upon quenching. Tempering a steel in this way actually decreases its strength a bit, but the benefit is improved toughness.
Successfully quenching a steel to make martensite requires rapid cooling throughout the body of the sample, which means that thick pieces like engine blocks cannot be strengthened in this way.
Regarding drop top ron's comments, there is no such thing as tempering aluminum, at least in the sense of tempering steel. Certain aluminum alloys can be strengthened by a process known as "precipitation" or "age" hardening, but this is a time-and-temperature dependent process, and such alloys would actually lose any strength gained by this treatment if they were to continue to be subject to heat. I know that aluminum is used to make engines, but probably not age-hardened aluminum.
I have heard of "seasoning" newly-purchased cookware as was mentioned earlier. So, yes, if you want to season your new engine, rub a little vegetable oil on it as soon as you get your new car home from the showroom.
Nothing will happen to cast iron, microstructurally-speaking, until it is heated to 727 degrees C, the temperature of the iron/iron-carbide eutectoid. That's 1340 degrees F, and no car engine operates anywhere near that temperature. So, as Wmachine says, the repeated heating and cooling that an engine undergoes in use has no effect on its microstructure.
To temper steel requires heating to at least 400 C, which which is about 750 F, so, again, no amount of use as car engine will cause tempering to occur. Only certain steels can be tempered, though, and these are steels that form a microstructure known as "martensite" upon quenching. Tempering a steel in this way actually decreases its strength a bit, but the benefit is improved toughness.
Successfully quenching a steel to make martensite requires rapid cooling throughout the body of the sample, which means that thick pieces like engine blocks cannot be strengthened in this way.
Regarding drop top ron's comments, there is no such thing as tempering aluminum, at least in the sense of tempering steel. Certain aluminum alloys can be strengthened by a process known as "precipitation" or "age" hardening, but this is a time-and-temperature dependent process, and such alloys would actually lose any strength gained by this treatment if they were to continue to be subject to heat. I know that aluminum is used to make engines, but probably not age-hardened aluminum.
I have heard of "seasoning" newly-purchased cookware as was mentioned earlier. So, yes, if you want to season your new engine, rub a little vegetable oil on it as soon as you get your new car home from the showroom.
April 18th, 2013, 01:16 PM
#13
"Car"mudgeon
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Location: Perry, GA
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Here is more on what I was saying. Not saying what you wrote is wrong but I believe we are talking about different things.
New vs. “Seasoned” Blocks
It used to be that no self-respecting performance enthusiast would consider using a new block. This
wasn’t simply a matter of money. New blocks just didn’t make as much power as well seasoned used
blocks. Engine blocks, like football quarterbacks, get better with age. In the case of a block casting,
countless cycles of heating up and cooling down help to “season” the metal. When a block is first
cast and then machined on the assembly line, it develops internal stresses. The heating/cooling
cycle allows these stresses to “relax,” until finally the block becomes dimensionally stable. In the
opinion of many top ranked racers, an engine does not achieve maximum power output until it has
been honed three or four times; it takes that long for the cylinder bores to settle down and hold the
perfectly round shape that promotes a “tight” ring seal.
New vs. “Seasoned” Blocks
It used to be that no self-respecting performance enthusiast would consider using a new block. This
wasn’t simply a matter of money. New blocks just didn’t make as much power as well seasoned used
blocks. Engine blocks, like football quarterbacks, get better with age. In the case of a block casting,
countless cycles of heating up and cooling down help to “season” the metal. When a block is first
cast and then machined on the assembly line, it develops internal stresses. The heating/cooling
cycle allows these stresses to “relax,” until finally the block becomes dimensionally stable. In the
opinion of many top ranked racers, an engine does not achieve maximum power output until it has
been honed three or four times; it takes that long for the cylinder bores to settle down and hold the
perfectly round shape that promotes a “tight” ring seal.
April 18th, 2013, 01:59 PM
#14
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Location: The Hudson Valley
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Well, you just blew your credibility on this subject with me, by quoting from a book without providing any attribution whatsoever.
The above quote is from The Step-By-Step Guide to Engine Blueprinting
by Rick Voegelin, ©1997 by Cartech Books, North Branch, MN.
Your having quoted it with no reference whatsoever indicates that you have no idea of the value of primary versus secondary sources of information to the researcher (ie: the CO member).
Mr. Voegelin's having made this statement with absolutely no attribution or other reference whatsoever indicates that he has little to no idea of what he is talking about (nor of how to write a work of nonfiction), and is simply re-spouting something that someone told him once, because it sounds good to him.
This is not the basis of scientific research or knowledge, but rather of urban myth and "truthiness."
If the best you can do is to quote an author from a hack publishing house, who, himself, does not footnote his work, versus two people with backgrounds in metallurgy, then I'm afraid that your argument is lost.
- Eric
The above quote is from The Step-By-Step Guide to Engine Blueprinting
by Rick Voegelin, ©1997 by Cartech Books, North Branch, MN.
Your having quoted it with no reference whatsoever indicates that you have no idea of the value of primary versus secondary sources of information to the researcher (ie: the CO member).
Mr. Voegelin's having made this statement with absolutely no attribution or other reference whatsoever indicates that he has little to no idea of what he is talking about (nor of how to write a work of nonfiction), and is simply re-spouting something that someone told him once, because it sounds good to him.
This is not the basis of scientific research or knowledge, but rather of urban myth and "truthiness."
If the best you can do is to quote an author from a hack publishing house, who, himself, does not footnote his work, versus two people with backgrounds in metallurgy, then I'm afraid that your argument is lost.
- Eric
April 18th, 2013, 02:16 PM
#15
"Car"mudgeon
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Eric that quote if you have been following the thread whatsoever is but one of the many results on Google that back up what I have learned through experience. Regardless of your creditability or attribution, it is free to Google, Bing or whatever and copy and paste as long as I am not profiting from this whatsoever. You can tell from the font that it was copied from another source. I am not here to win any arguments, I was at first trying to answer the original post with my experience in that respect that has been danced all around by almost every one here by quoting crap about metallurgy. If you have experience with building and racing a new block and old block combined, your input is welcome by me.
Bottom line is that she (the OP) does not need to stress relieve anything nor does she need to sink the $$ into vibrational or cryogenic process.
Bottom line is that she (the OP) does not need to stress relieve anything nor does she need to sink the $$ into vibrational or cryogenic process.
April 18th, 2013, 02:21 PM
#16
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- Eric
April 18th, 2013, 02:28 PM
#18
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Sorry Jaunty but I disagree about tempering aluminum. Please refer to the AAMA design guide as it gives design stresses and average ultimate stresses for all different grades of aluminum (there are too many to go into).
I will attempt to clarify my use of the word "tempering" in my previous post. The tempering I am referring to is not an elevation of temperature but the cryogenic tempering process, where metal (steel or aluminum) is placed in a liquid nitrogen bath and taken to -300 degrees F. Here is a link to the company we were in discussions with....
http://www.300below.com/
As stated before, there are benefits to the process in SOME applications. For a street driven vehicle I question the expense. Personally, I would rather spend the money on better machining and better parts to make my engine perform to a higher level.
Regards....
I will attempt to clarify my use of the word "tempering" in my previous post. The tempering I am referring to is not an elevation of temperature but the cryogenic tempering process, where metal (steel or aluminum) is placed in a liquid nitrogen bath and taken to -300 degrees F. Here is a link to the company we were in discussions with....
http://www.300below.com/
As stated before, there are benefits to the process in SOME applications. For a street driven vehicle I question the expense. Personally, I would rather spend the money on better machining and better parts to make my engine perform to a higher level.
Regards....
April 18th, 2013, 02:31 PM
#19
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To further expound on tempering of aluminum there are ways to do so (primarily extrusions) using solutions, etc. When I worked for an Aluminum extruder/fabricator we extruded 6063 and after the "tempering" process we had a 6063-T5 material. Keep in mind tempering can be done by raising temperature or lowering temperature in a controlled fashion.
April 18th, 2013, 02:34 PM
#20
"Car"mudgeon
Join Date: Feb 2011
Location: Perry, GA
Posts: 5,191
Sure, it is free, and the quote falls under "fair use" doctrine, but my point is that if you are trying to prove an objective scientific fact, then you do your argument no favors by neglecting to post a source for your information - it could be a quote from Bozo the Clown for all we know, unless you tell us otherwise.
- Eric
- Eric
I am voicing my opinion as asked by Karen on her thread " Any opinions on residual metal stress?" I am not trying to prove anything, just merely trying to voice my experience with the subject at hand. Not whether or not aluminum gets harder or more brittle with heat and a quench bath or whatever. Like I said before she doesn't need to stress relieve anything nor does she need to sink the $$ into vibrational or cryogenic process. Nuff said I am done with any Bozo that thinks she does.
Seriously though, she should feel free to post any question she wants
April 18th, 2013, 08:37 PM
#23
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Wow! Thanks to everyone! First, for those who want the "short course" check out the Metal Science Services site, Technical info has an excerpt from the ASM handbook on heat treating. Bottom line for me? Forget the stress relief! The block matches the rest of the car, and I was just looking to maximize protection against that one stomp that could change everything.... It's clear that there are definite changes that occur during the cryogenic process, but as I see it, they're more a result of chemical conversions than a decrease in entropy. Just MY opinion! 
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