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..........

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/  

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?)

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.

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

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.

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...

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

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.  

But thats part of the blacksmithing tradition! Lol besides A36 is as much a crap shoot as rebar 

Allen heads will exceed grade 8. Great for tension, sucky for shear.

 

With grade 8 pluss washers and nuts one can get friction to take some of the strain off the bolts in shear. 

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

​Try again Charles. 

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 April 21, 201511 yr by Charles R. Stevens

100 points = 1% carbon AKA .01  Carbon;    

so 1 point =.0001 carbon

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 

Good Mourning,

The finger is the devil!!!! One Point of Carbon is ??01, in the Steel numbering game.

Neil

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

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%?

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)

I am glad I stuck my foot in my mouth...

I'm reedicated and a new guy gets off on the right foot

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.

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

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?

Thats camoage, he is capitalizing on his uncany resimbulace to a garden gnome...