SReynolds

Steel Grade for "Grade 8 Bolt" ???

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If the grade 5 bolt is 1541 what is a grade 8 bolt. Some folks make tools from the large grade 8 bolts it seems..........

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Bolt grade are by physical specification not by chemistry.  Basically a grade 8 bolt can be made from any alloy as long as it meets the physical specs.  The following company site explains a little but because it does not list the alloys only the carbon content it's hard to say what kind of steel is used.

http://www.portlandbolt.com/technical/specifications/sae-j429/  

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OK.

but, grade 5 and grade 8 are both .28 to .55 carbon.............????????? Then why have  a 5 and also an 8? 

 

Why do folks demo tool making and insist upon grade 8 (not grade 5?)

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Heat treat may vary between them.  

As to why they demand one over the other perhaps they don't know they may vary like that; or perhaps they do know that the stronger grade is more likely to be at the higher end of the variance.

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I would assume heat treet, as what I learned in the automotive industry indicates that the grade 8 can provide higher clamping loads but is not recomended for loads in shear, wile the grade 5 provides adiquate clamping force but as it is a bit more malluable it serves better in shear. If the range is 3 and 5 point carbon, i would bet that most grade 5 are the lower and the 8 the higher tho depending on the costs, they may make them both from the same (say mid way) just making grade five as forged, wile quenching the grade 8 (not unlike japanise sword smith choses his corbon content to obtain a one step heat treat). Manufacturing is about cost cutting, so if the proces can be stream lined, handling and material costs cut that is the way they will go, 

i bet a 2" grade 5 would make a nice post anvil

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I have some shafting from a manual trans. Big stuff like 1 3/8" etc. I can't cut that with a file. I think that may be forged into a hardie cut and left to cool w/o hardening it...it may be ok. I don't need it to be super hard for a hardie /hot cut.

If you can't cut into steel with a file that may be 60 or 80 point carbon I bet (???)

 

Did you mean to reference .30 to .50 point carbon,,,,,, as opposed to 3 to 5 point? You can't buy 5 point carbon. Lowest I have seen is .18 point.

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transmission stuff may be case hardened for wear; I'd check the center of a piece just in case...

I like my hardies softer than the hammer face a lot easier to dress the hardy edge than the hammer face after a student has been too enthusiastic...

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A safety note for those who don't know, most common coating on a grade 8 bolt is cadmium.  That yellowish/gold/blue tint.  If you think breathing zinc fumes is a fast way to get sick or die, putting cadmium coated stuff in your forge is nastier.  Don't do it.  Scary s**t.

 

OK.

but, grade 5 and grade 8 are both .28 to .55 carbon.............????????? Then why have  a 5 and also an 8? 

 

Why do folks demo tool making and insist upon grade 8 (not grade 5?)

​There are other elements used in alloying steel in addition to carbon.  Grade 5 has one set of characteristics that include yield strength, carbon content, perhaps other characteristics.  8 has a higher required strength, therefore perhaps different carbon, perhaps different other alloyed elements.  And when we blacksmiths use a mystery steel "off label" as it were with atypical use and heat treatment then we enter the world of experimentation rather than cook book technique.  

When I use a scrap steel (anything I don't have certs for) I write down what it was, what I used it for, what heat treat I did, and how it held up.  After 25 years looking back on that list I've found that it's much more economical to buy known steel.  

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Shart hand, .3-.5 percent carbon or .30-.50, that is .003 carbon  and .997 0f everything else. 

​Try again Charles. 

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How many desimal point off am I Artist? .1 or 1 percent should be .001, that is 1/10th of 1/100th is 1/100th. Not the greatest at math, but i got the basics, have I mis understood that a "point" of carbon is .1 of 1 pecent? Or is it .01 of 1 percent?  (1/10,000th?

that would make bolts 10-30 point?

Edited by Charles R. Stevens

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See what happens when you raise girls?! Sinility sets in! Thank you Master Powers, one of manythings I seem to have forgotten. So I was only of by a factor of 10, lol 

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100 points equal 1%, 1% equals  .01 so shift the decimal over two spaces! .0001 equals 1 point very low carbon steel.

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I was thinking the same thing, was confused, but didn't didn't want to ask.

 

is 18 point still shown as .18 ? Same as 18%?

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100 points equals 1% Carbon so 18 points is NOT 18%!  is is the same as 1018  low carbon where 18% would be 7 times more carbon than cast iron begins at. 18 points is .0018  (see my post above: 1 point equals .0001 so multiply by 18 gives you .0018)

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The way I see it explained in a lot of old books is that a point is "one percent of one percent."  Everyone's probably already got that by now, but I threw in my 2 points just in case.

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so I don't want to be a 1%'er; I want to be a Pointer!   Somehow that didn't come out right...

​So that's why you wear the red hat?

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