stainless grade hardness??
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Thanks Walt.... I had a feeling it was on the low side....I imagine a marine grade will be closer to if not grade 8.... I just bought a bunch of SS allen head bolts off ebay that are 304 which will be good enough for side covers, valve covers ect...I was going to buy some for the head bolts but I want something a little harder for those....
A number of years ago I put this question to an Engineer's Engineer...the guy is very learned and experienced. After a 5 minute dissertation of 'if's and 'ands' he said: for the purposes were were utilizing the SS 304 fasteners consider them Grade 5. BTW, 8 is not automatically better than 5 for all purposes.
Here is a chart that looks like it has your fastener on it. Stainless doesn't have a proof load value on this chart, but that is nothing but a conservative yield strength when the fastener begins to stretch.
https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
Thanks guys for the replies and information.... The bolts in question I believe are a low grade of SS mainly used in sanitary conditions like resturant equipment, meat cutting, hospital equip where strength isn't a concern but need to be free from rust and contamination..... I purchased some ss bolts locally and they have a slight magnetisim and feel pretty soft when cutting and filing...again these will be fine for covers and such, my concern was stretching on the heads..but I suppose since I won't be taking them in and out and torquing them over and over these will be ok...
OS brings up a point that needs expanding on.
Higher grade bolts are stronger in tensile strength but alos harder.
In some cases a grade 8 bolt will snap in an aplication that 5 will not however.
This is because the 5 is more forgiving and will stretch....
Stainless is very hard stuff because of the chrome, to compensate they add nickel ( in good stainless ) or magnese ( in cheap shitty stainless, the Kind the Chinee are fond of making things like BBQs and consimer goods from ).
Also stainless is more noble that common steel.
This menas because of galvonic action a piece of stainless will turn comon steel into an Anode and force the comon steel to corode to preserve the shine of the stainless.
Try this one:
Put a stainless bolt in with a comon nut out in the rain.
Leave it there for a while and see how fast the comon steel rusts and just how hard it is to remove the nut.
Higher grade bolts are stronger in tensile strength but alos harder.
In some cases a grade 8 bolt will snap in an aplication that 5 will not however.
This is because the 5 is more forgiving and will stretch....
Stainless is very hard stuff because of the chrome, to compensate they add nickel ( in good stainless ) or magnese ( in cheap shitty stainless, the Kind the Chinee are fond of making things like BBQs and consimer goods from ).
Also stainless is more noble that common steel.
This menas because of galvonic action a piece of stainless will turn comon steel into an Anode and force the comon steel to corode to preserve the shine of the stainless.
Try this one:
Put a stainless bolt in with a comon nut out in the rain.
Leave it there for a while and see how fast the comon steel rusts and just how hard it is to remove the nut.
Sir,
Is this not where bi-metalic corrosion comes in, we had a metalagist on station and he used to rev us for using stainless bolts on aluminium with out some form of anitcorrosion paste. Something about the metals being far apart on the priodic table and attacking one another.
:laugh: we must have some bi-metalic members
Is this not where bi-metalic corrosion comes in, we had a metalagist on station and he used to rev us for using stainless bolts on aluminium with out some form of anitcorrosion paste. Something about the metals being far apart on the priodic table and attacking one another.
:laugh: we must have some bi-metalic members
Yes:
Nobolity of metals.
There are plenty of examples you may be fami,iar with.
Zink anodes attached to the hull of a ship that corrode rapidly because the iron forces the zink to corrode in its place.
But if you start to put brass or stainless nuts and bolts on the same ship's hull you are defeating the purpose of the zink because the more noble brass or stainless will cause the iron in the hull to corrode in its place.
There are pastes as you say to reduce this effect.
Here in Canada we used to use Aluminum wire in homes and where Aluminum meets copper connections this anti oxides paste was to be used to prevent trouble.
In practice things did not always work out that well and aluminu8m is awful wire to use in small gauges anyways.
Interestings thing happens when you bolt to disimilar metals together and they start to corrode.
In copper and aluminum the too metals actualy start to flat off from their base and oxidize. But they also attempt to alloy together.
This causes ratcheting as the flakes of metal push and pull againts each other and usualy this loosens the connection and bolt holding them together.
If you thread a stainless steel bolt into an iron block the same things happen but instead of loosening the corroded metal has no place to go and the intersection between the threads closes up completely.
This makes unscrewing almost impossible.
Nobolity of metals.
There are plenty of examples you may be fami,iar with.
Zink anodes attached to the hull of a ship that corrode rapidly because the iron forces the zink to corrode in its place.
But if you start to put brass or stainless nuts and bolts on the same ship's hull you are defeating the purpose of the zink because the more noble brass or stainless will cause the iron in the hull to corrode in its place.
There are pastes as you say to reduce this effect.
Here in Canada we used to use Aluminum wire in homes and where Aluminum meets copper connections this anti oxides paste was to be used to prevent trouble.
In practice things did not always work out that well and aluminu8m is awful wire to use in small gauges anyways.
Interestings thing happens when you bolt to disimilar metals together and they start to corrode.
In copper and aluminum the too metals actualy start to flat off from their base and oxidize. But they also attempt to alloy together.
This causes ratcheting as the flakes of metal push and pull againts each other and usualy this loosens the connection and bolt holding them together.
If you thread a stainless steel bolt into an iron block the same things happen but instead of loosening the corroded metal has no place to go and the intersection between the threads closes up completely.
This makes unscrewing almost impossible.
I try to keep things simple in my life. There are times that Stainless-steel has to be used. But what stainless to use?
I use a magnet and see if the hardware is pulled into it. If it is NOT pulled in, it is true stainless-steel and for most applications it is too soft to hold a lot of torque/force. I would not use it on a jack-shaft or mounting bolts for brake drums or chain tensioner device.
If the magnet does pull it in, it has a high iron content and is much higher shear strength and would work well in high stress areas. These bolts/fasteners will over time rust a little, but are better in the long run over carbon steel or Chrome-validium fasteners.
After spending 18 years at sea, I can tell you what really is stainless or not, and what will hold a load for a long time,or not.:thumbsup:
I use a magnet and see if the hardware is pulled into it. If it is NOT pulled in, it is true stainless-steel and for most applications it is too soft to hold a lot of torque/force. I would not use it on a jack-shaft or mounting bolts for brake drums or chain tensioner device.
If the magnet does pull it in, it has a high iron content and is much higher shear strength and would work well in high stress areas. These bolts/fasteners will over time rust a little, but are better in the long run over carbon steel or Chrome-validium fasteners.
After spending 18 years at sea, I can tell you what really is stainless or not, and what will hold a load for a long time,or not.:thumbsup:
Its the Nickel that makes a good stainless.
The higher the nickle content the tougher the steel.
Infact remove the chrome and add the nickel and steel becomes armour plate.
Not harder but tougher and harder to penetrate.
As I said before the cheaper nickel free alloys are the shitty ones.
A few years back when nickel went over 20 bucks a pound ( ( 10 fold increase in 8 years ) the Chinese started to use a lot of real y low end stainless substitute products.
These have not lasted well because they are brittle and not as corosion resistent.
Super alloys like MONEL ( looks like gold and never tarnishes ) or INCONEL ( the high temperature stainless we developed for the first jet engine and turbo chargers durring WWII ) all have high nickel concentrations.
Some of the super stainless steels contain no iron at all.
For you Rob, you shoudl be looking fo rthe free machining stainless steels that have a touch of sulpher added to the mix.
This allows for faster easier machining ( usualy an S designiation in the name code ).
I read in the news about a clock made someplace in the USA.
It was wound up and is suposed to run counting th days for the next 1000 years.
Its gears are a Monel Alloy that is the exact same ratio as the copper to nickel in the ore from Creighton mine.
I don't know if they discovered that by fluke or experiementation but it used to be a marketing gimic.
In contrast to the allow they make from it take a chunk of that ore and get it wet and a chemical reaction starts with the air and it starts to heat.
Get enough of it in a pile self heating and it will burn.
I figuere there is around 3 or 4 billion dollars worth of the stuff burning between 5800 and 3800 level that can't be recoverd.
http://www.ebay.ca/itm/1961-NS-Sava...724?pt=LH_DefaultDomain_0&hash=item23232c472c
The higher the nickle content the tougher the steel.
Infact remove the chrome and add the nickel and steel becomes armour plate.
Not harder but tougher and harder to penetrate.
As I said before the cheaper nickel free alloys are the shitty ones.
A few years back when nickel went over 20 bucks a pound ( ( 10 fold increase in 8 years ) the Chinese started to use a lot of real y low end stainless substitute products.
These have not lasted well because they are brittle and not as corosion resistent.
Super alloys like MONEL ( looks like gold and never tarnishes ) or INCONEL ( the high temperature stainless we developed for the first jet engine and turbo chargers durring WWII ) all have high nickel concentrations.
Some of the super stainless steels contain no iron at all.
For you Rob, you shoudl be looking fo rthe free machining stainless steels that have a touch of sulpher added to the mix.
This allows for faster easier machining ( usualy an S designiation in the name code ).
I read in the news about a clock made someplace in the USA.
It was wound up and is suposed to run counting th days for the next 1000 years.
Its gears are a Monel Alloy that is the exact same ratio as the copper to nickel in the ore from Creighton mine.
I don't know if they discovered that by fluke or experiementation but it used to be a marketing gimic.
In contrast to the allow they make from it take a chunk of that ore and get it wet and a chemical reaction starts with the air and it starts to heat.
Get enough of it in a pile self heating and it will burn.
I figuere there is around 3 or 4 billion dollars worth of the stuff burning between 5800 and 3800 level that can't be recoverd.
http://www.ebay.ca/itm/1961-NS-Sava...724?pt=LH_DefaultDomain_0&hash=item23232c472c
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used to work on salt-water cooled marine engines.....brass fittings in alumium intake manifolds....try and get one of those out after a few years..:hammer:
might as well throw the manifold in the dumpster, it was as if the two metals had become one....:doah:
A lot of the parts we made in the old EXXON Research machine shop were made from stainless, inconel , monel, etc to resist the various exotic chemicals that flowed through them....I got to HATE that stuff....giant lathes, with giant carbide tools turning out giant parts with a wicked blue-hot cotinuous chip peeling off them...evil stuff to machine....came off like razor wire..The lathes were so big you had to climb up stairs to get to the headstock and you would shift the control levers using both hands. We had these big hooks we used to grab hold of the chip and pull it away so it didn't get caught up in the spinning chuck....and we would try to break the chip every so often.....if you didn't it would wind up grabbing 300 ft of coil out of the belly of the lathe and start whipping it around....then you'd better hit the panic button and run!
now that I'm home just tinkering I get to make little mini bike parts out of nothing but aluminum, brass, CRS or Leadloy....it's like a dream....:smile:
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might as well throw the manifold in the dumpster, it was as if the two metals had become one....:doah:
A lot of the parts we made in the old EXXON Research machine shop were made from stainless, inconel , monel, etc to resist the various exotic chemicals that flowed through them....I got to HATE that stuff....giant lathes, with giant carbide tools turning out giant parts with a wicked blue-hot cotinuous chip peeling off them...evil stuff to machine....came off like razor wire..The lathes were so big you had to climb up stairs to get to the headstock and you would shift the control levers using both hands. We had these big hooks we used to grab hold of the chip and pull it away so it didn't get caught up in the spinning chuck....and we would try to break the chip every so often.....if you didn't it would wind up grabbing 300 ft of coil out of the belly of the lathe and start whipping it around....then you'd better hit the panic button and run!
now that I'm home just tinkering I get to make little mini bike parts out of nothing but aluminum, brass, CRS or Leadloy....it's like a dream....:smile:
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