Thread: Heat Treatment of 4140

This is a continuation from Bob's thread on offsetting in a 4 jaw chuck.. http://www.woodworkforums.com/f65/of...ur-jaw-137224/

The simple version, heat to bright red , and hold at bright red heat for a few minutes, dunk in oil, and temper...

Now, the longer version, possibly more complete version.

The information below comes from "Heat Treatment, Selection, and Application of Tool Steels" by William E Bryson, I can recommend his down to earth practical style, and wide range of steels covered. Good value. $38.95 hardcover from Amazon [ame="http://www.amazon.com/Heat-Treatment-Selection-Application-Steels/dp/156990376X/ref=tmm_hrd_title_popover"]Amazon.com: Heat Treatment, Selection, and Application of Tool Steels (9781569903766): William E. Bryson: Books[/ame], there is something weird about amazon's pricing they have the paperback version for $349.97 ?

Apologies for the quality of the scans, I trust it's at least readable...









The question as to whether or not you can water quench 4140, is still open... chances are you'll get the results as shown below



I suspect you can water quench anything, depending on the details of the process and exactly what you are trying to achieve.

Regards
Ray

Into the rabbit hole we go lol

Originally Posted by RayG

That's what I thought too, until I read the Houghton documentation, faster cooling (beyond the boundary on the CCT curve) won't make it harder, just increases the risk that the outside will convert to the harder material before the middle, and hence "ping" the crack appears.

It follows that the CCT curve will differ between different alloys, so some are suited to faster quenching (water) and some can be quenched more slowly, even, air quenched like A2.

Yes, but without a time temperature transformation diagram for 4140 you dont know if oil quenching(and there are plenty of different oils) has kept you beyond the boundary of on the CCT curve. Even if you have the diagram how would you measure it? In a lot of parts you would be happy to trade off some hardness for toughness as you will be tempering anyway, not so on a wear surface(unless it breaks off of course ).

Using oil also deceases the hardness depth(not a problem for BT,s center)
So they have high speed oils... but wait I thought they were trying to slow things down?
Water(well brine really) will give you the hardest surface, oil may or may not give you as hard a surface. Water may or may not crack that surface.

As for tempering I would be interested to see what happened without it(again I am talking about just quenching a small area of a simple shaped, lightly loaded part)

I'd say the part in table 11.10 was designed to crack on water quenching.lol

Stuart

Given that I have the oven, albeit in bits, I just bought the book. Thank you for that Ray.

Bob.

I've ordered a copy as well, maybe we'll all end up on the same page lol.

Hi BT,
Can I ask what postage cost you for your book if you bought it from Amazon?
I paid $42.94 with free shipping from bookdepository as their checkout it easier and I'm feeling to lazy to sign up for Amazon. Its a little late to think about it now but is the Amazon price $AU?

Stuart

F%&K ME! I got touched. Paid Amazon $48.51 including shipping. I looked at Book Depository's UK site and it said the title could not be found. Also had a look at Alibris to no avail.
I obviously didn't look hard enough. Book Depository is a winner due to the free and FAST shipping. I suppose my Amazon purchase will roll up in 6 weeks time. Still, it will be a nice surprise because I will have forgotten about it by then.

A numb Bob.

Sloth finally pays off!
Thanks BT I was wondering it if was worth the trouble of signing up to yet another site, I guess I have my answer at your expense sorry.
Stuart