1144 Fatigueproof vs Grade 8.8 Steel

D

Dylanm09

Plastic

Joined

Jul 1, 2020

• Jul 1, 2020

• #1

Currently working on a quote and had questions on processing for a general call out of "Grade 8.8 Minimum " as a material requirement on a print.

Was wondering If we just processed as Fatigueproof if it would meet the requirements. Finding that Grade 8.8 has requirements of 800Mpa Tensile and 640Mpa Yield (80% of 800) minimum. Both Fatigueproof and Stressproof meet the minimum Yield strength requirements but only Fatigueproof meets the Tensile, Stressproof just misses it @ 793 Mpa minimum.

Our usual process for Grade 8.8 was obtain normal 1144 material and Heat Treat to obtain the mechanical requirements, but this adds cost. Was just wondering if anyone has come across this situation before, and if I am missing details of requirements to be classed as Grade 8.8

Appreciate your input!

 

F

flubber

Plastic

Joined

Jun 11, 2015

• Jul 1, 2020

• #2

If I recall correctly there is a difference between generic 1144 and Niagara-LaSalle's 'STRESSPROOF' trademarked steel. Same thing with their FATIGUE PROOF and ETD-150 steels.

In many instances, using these steels will eliminate a subsequent heat treatment operation. The attached link will take you to technical data sheets.

Niagara Lasalle Corporation - Products

I wish I still had my standards book from the Industrial Fasteners Institute. Your print calls for CLASS 8.8 MINIMUM. It should not be confused with 'GRADE 8' which is totally different, but VERY EASY TO CONFUSE.

ASTM, SAE and ISO Grade Markings for Steel Fasteners - American Fastener Technologies Corporation

 

E

eaglemike

Stainless

Joined

Apr 25, 2014

Location

san diego

• Jul 2, 2020

• #3

As he said above ^^^
Wanted to add that machining the various versions of 1144 has always been easy. be sure to keep it oiled up after machining, prior to oxide or whatever. It will rust pretty quickly in my experience if not protected.
Good luck!

 

M

MattiJ

Titanium

Joined

May 31, 2017

• Jul 2, 2020

• #4

Class 8.8 has also minimum requirement for elongation before break and 1144 might fail on that aspect even with good heat treat.

Despite the name I’d also double-check the fatique limit as sulphur is usually bad news also for that.

 

Mtndew

Diamond

Joined

Jun 7, 2012

Location

Michigan

• Jul 2, 2020

• #5

I can't say anything about your requirements, but man... hogging 1144 Fatigueproof on a lathe is something I miss doing. That stuff cuts so nice.
And the person above is spot on about tossing a coating of oil on it after machining it.

 

johnoder

Diamond

Joined

Jul 16, 2004

Location

Houston, TX USA

• Jul 2, 2020

• #6

also minimum requirement for elongation before break

Click to expand...

Easily the most important requirement for metal that has to work for a living

Wright Aeronautical checking such

 

D

Dave G.

Cast Iron

Joined

Mar 24, 2005

Location

Clev, OH

• Jul 2, 2020

• #7

I don't think you can use 1144 or other resulfurized steels for 8.8 bolts. I think the max sulfur is 0.025%S IIR correctly.

 

4GSR

Diamond

Joined

Jan 25, 2005

Location

Victoria, Texas, USA

• Jul 2, 2020

• #8

If corrosion is an issue, don't use. 1144. will corrode much faster than 8.8 grade material for a fastener will. It has to do with the high Sulfur content of 1144. Something like .04%. I don't have my Jorgensen book handy to look it up. Don't ever get 1144 near HCL!!! Don't ask me how I know this!!!

 

Orange Vise

Titanium

Joined

Feb 10, 2012

Location

California

• Jul 3, 2020

• #9

Without looking at the exact numbers, my guess is that Stressproof is going to fall slightly short of the requirements.

A more likely candidate (which you'll need to verify) would be etd 150, which is Niagra's direct substitute for 4140HT.

 

R

richard newman

Titanium

Joined

Jul 28, 2006

Location

rochester, ny

• Jul 3, 2020

• #10

4GSR said:

If corrosion is an issue, don't use. 1144. will corrode much faster than 8.8 grade material for a fastener will. It has to do with the high Sulfur content of 1144. Something like .04%. I don't have my Jorgensen book handy to look it up. Don't ever get 1144 near HCL!!! Don't ask me how I know this!!!

Click to expand...

So, is it the sulfur in 12L14 that makes it rust so easily? Always wondered about that.

And +1 for avoiding HCL! I won't keep any in the shop, somehow it manages to rust everything around even in a tightly closed container!

 

4GSR

Diamond

Joined

Jan 25, 2005

Location

Victoria, Texas, USA

• Jul 3, 2020

• #11

richard newman said:

So, is it the sulfur in 12L14 that makes it rust so easily? Always wondered about that.

And +1 for avoiding HCL! I won't keep any in the shop, somehow it manages to rust everything around even in a tightly closed container!

Click to expand...

Yep! The way we found out that HCL would eat it up, we made some parts and complet injection tools out of 1144 stressproof that were sent down hole in the oilfield. The acid ate holes in the metal that look like swiss cheese when it came out of the hole. Needless to say, a lot of finished parts had to be scrap out. Expensive lesson to learn. I'm glad my name wasn't on that design!!! Ken