Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Largest Manufacturing Technology Community on the Web
Stay Connected:
difference between 4140 prehard, 4140 HT, and 4140 TGP
- Thread starter fettersp
- Start date
- Replies 24
- Views 8,751
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
No significant difference between 4140HT, 4140Q&T and 4140PH. Those are usually used interchangeably. TGP can be hardened or not...
Rob F.
Diamond
- Joined
- Aug 5, 2012
- Location
- California, Central Coast
Why would annealed have lead?
Hardplates
Stainless
- Joined
- May 8, 2019
- Location
- What once was a free country
Doesn't that crap cause cancer in California?
Annealed is in its soft state. Heated to its austenitization point and then cooled slowly so it is soft, normalized is heated and then allowed to air cool and depending on the alloy could be about the same as annealed or much harder. It could be heat treated to meet specs but would likely cost more than new material. Prehard, Heat treat, Quenched and tempered, Commercial heat treat......all different ways of saying the same thing. Usually it is in the mid to low 30s but not always. If the job calls out hardened material it should call out a hardness spec.....
Rob F.
Diamond
- Joined
- Aug 5, 2012
- Location
- California, Central Coast
Annealed would be softer than prehard. Not sure how much but that should be easy info to find. My understanding is that lead is added so chips get broken up easily to avoid long stringy chips.
Do they have a hardness spec on the print? Or will it go to heat treat?
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
4140 annealed does not contain any significant amount of lead. Annealed is usually about 10Rc in hardness. The pre-hardened versions usually range from ~26 Rc to 32 Rc - depending on where you get it.
Rob F.
Diamond
- Joined
- Aug 5, 2012
- Location
- California, Central Coast
If 4140 has lead is that then called out as 41L40? Dont know much about leaded steel other than I cant forge or weld it very well....
CarbideBob
Diamond
- Joined
- Jan 14, 2007
- Location
- Flushing/Flint, Michigan
TGP means turned ground and polish. Says nothing about hard. Could be dead soft or 50+.
What do your hardness files or Rockwell tester say?
If specked as pre-hard the part is very unlikely bound for heat treat as that would be silly and hard to control.
I'd consider mixing your laying around stock on a job dangerous but your choice to play the odds.
Bob
What do your hardness files or Rockwell tester say?
If specked as pre-hard the part is very unlikely bound for heat treat as that would be silly and hard to control.
I'd consider mixing your laying around stock on a job dangerous but your choice to play the odds.
Bob
carlherrnstein
Aluminum
- Joined
- Apr 18, 2015
- Location
- Ross County, Ohio
Call the customer and ask. Tell them you have a piece of stock that isn't prehardened that you can make the part(s) from for $X less. They may say no but who cares your not the one buying it they are.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Use the TGP for something more appropriate. Buy the needed pre-hard material, don't mess around when it comes to material callout.
TGP comes in handy a lot. It's usually pretty hard on the OD because of the surface condition. Maybe .025" deep. Use the right material. It's bad mojo to start messing and guessing.
R
crossthread
Titanium
- Joined
- Aug 5, 2004
- Location
- Richmond,VA,USA
Rob F. I'm surprised that you have a problem welding leaded steel. I use 12L14 from time to time since it machines so well. I have had very good results welding it. I can't say as I have ever tried forging it however.
athack
Stainless
- Joined
- Nov 2, 2009
- Location
- Michigan USA
41L40 use to have lead to make it easier to machine. Most mills now add calcium instead.
crossthread
Titanium
- Joined
- Aug 5, 2004
- Location
- Richmond,VA,USA
Gbent. None of the parts that I make for critical applications use 12L14. 4140 is kind of my go to metal for that sort of thing. I know 12L14 is not considered generally good for welding but I really haven't had any problems with it. I use mig with normal shield gas and the same wire I use for everything else. You do get a bit of splatter but I think that may be the lead component just being blasted out.
