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Is cold rolled stronger or harder than grade 5 bolts?
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School Of Hard Knock
Posted 7/11/2016 13:37 (#5405218)
Subject: Is cold rolled stronger or harder than grade 5 bolts?


Central ND		Or maybe I should ask if it is a better choice for deck pins.......I need to replace some reomvable deck pins on the adjustable base deck on a 20 ton press. They are 5/8th diameter.
Which is a better choice? Cold rolled shaft of grade 5 bolt stock?
TIA

Edited by School Of Hard Knock 7/11/2016 13:42
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JohnW
Posted 7/11/2016 14:01 (#5405242 - in reply to #5405218)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


NW Washington		My guess is that a Grade 5 bolt would be the better of the two. A Grade 8 bolt would be even better. This link has the shear and tensile strength of various sizes of SAE sized bolts, rated in psi. Looks like either would do the job.

http://tinelok.com/grade-5-vs-grade-8-fasteners/
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Dave7060
Posted 7/11/2016 15:36 (#5405346 - in reply to #5405242)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


JohnW - 7/11/2016 15:01

My guess is that a Grade 5 bolt would be the better of the two. A Grade 8 bolt would be even better. This link has the shear and tensile strength of various sizes of SAE sized bolts, rated in psi. Looks like either would do the job.

http://tinelok.com/grade-5-vs-grade-8-fasteners/


daltongeb - 7/11/2016 15:40

I would use stress proof, 115,000 psi tensil strength vs 85,000 for mild along with better resistance to fatigue. FWIW grade 5 bolts are approximately 120,000 psi, and grade 8 150,000 psi.


Tensile strength means nothing here, only shear strength. Tensile is how much pull it can take from one end to the other, since there will not likely even be a nut on the end, there will be zero tensile strain on the bolt.

Myself, I'd drill the holes bigger and use 1" cold rolled, that's what my 20 ton press uses. Better to be on the safe side when you get into an extreme press
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daltongeb
Posted 7/11/2016 16:17 (#5405401 - in reply to #5405346)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


Glad Valley SD		Shear strength is directly related to tensile strength, in most steels sheer strength is approximately 60% of tensile strength. And is a directly calculatable value based on tensile strength and hardness.
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daltongeb
Posted 7/11/2016 14:40 (#5405278 - in reply to #5405218)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


Glad Valley SD		I would use stress proof, 115,000 psi tensil strength vs 85,000 for mild along with better resistance to fatigue. FWIW grade 5 bolts are approximately 120,000 psi, and grade 8 150,000 psi.
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Istumped
Posted 7/11/2016 17:18 (#5405483 - in reply to #5405278)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


ne il
daltongeb - 7/11/2016 02:40

I would use stress proof, 115,000 psi tensil strength vs 85,000 for mild along with better resistance to fatigue. FWIW grade 5 bolts are approximately 120,000 psi, and grade 8 150,000 psi.




What he says. Grade 8 is as close to stainless steel as well.
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Now_What
Posted 7/11/2016 20:50 (#5405856 - in reply to #5405483)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


Istumped - 7/11/2016 03:18




What he says. Grade 8 is as close to stainless steel as well.


Stainless is an extremely poor choice and has nowhere the strength of a grade 8 bolt.

Anyone who has ever done material analysis with stainless knows as soon as you but a load on it the material starts to yield neck down immediately.

Stainless starts to yield around 25,000 - 32,000 psi and 304 for example has an ultimate strength around 73200 psi where a grade 8 bolt should be in 120,000 - 150,000 psi.



When you say cold rolled... Which grade of steel.

Cold rolled is a milling process that reforms hot rolled steel at ( or near) room temp to produce a more uniform sized product and strain hardens the steel to increase strength, realign the grain structure and decrease the size of the grain structure.

You can get cold rolled steel in 1018 in cold rolled form, 4140 in cold rolled form, 4330 in cold rolled form, 1144 in cold rolled form, the list goes on for ever.
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School Of Hard Knock
Posted 7/11/2016 22:36 (#5406157 - in reply to #5405856)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


Central ND		4140
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STOMN17
Posted 7/13/2016 09:56 (#5408773 - in reply to #5406157)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


You would be good with 4140 as the tensile is around 100k psi for cold drawn. Also, your shear should be distributed across 4 points on the press.
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E718
Posted 7/11/2016 14:48 (#5405283 - in reply to #5405218)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


Sac & Story county IA		A grade 5 5/8" bolt has a shear of about 10 tons.
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Clodbuster1
Posted 7/11/2016 15:09 (#5405309 - in reply to #5405218)
Subject: If you use bolts:


Make sure you only use the "shank" of the bolt that is full size, and not the threaded part as that will fail first since it is a smaller diameter where the threads are cut or rolled.
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Gerald J.
Posted 7/11/2016 15:35 (#5405345 - in reply to #5405218)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?



Consider 5/8" hitch pins as being a decent compromise of shear strength vs hardness. Hitch pins tend to be tough. Grade 5 bolts are definitely stronger than cold rolled steel or grade 2, and grade 8 definitely stronger than grade 5, but some engineers consider grade 8 to be brittle under shock loading.

Search for steel at http://www.mcmaster.com and click on "about steel" for a set of tables and properties of the various available alloys. There is lots of data there.

My Metals Handbook says for cold rolled sheet the yield strength is 30,000 to 35,000 PSI. McMaster-Carr says 54,000 PSI for grade 5 bolts.

LIkely the press structural steel is softer than grade 5 bolts.

Gerald J.
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wannabe2
Posted 7/11/2016 17:13 (#5405476 - in reply to #5405218)
Subject: RE: Is cold rolled stronger or harder than grade 5 bolts?


NW Montana

Its only a 20 to press. 5/8 forged hitch pins with a handle would be convenient if you can find them long enough.  
CR will work, grade 5 will work but the shank needs to go all the way through so the table stays level.

 

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