how do you temper steel? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > General Discussion> Hotrodders' Lounge
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 09-19-2002, 11:16 AM
bullheimer's Avatar
NEVER use credit cards!
 

Last journal entry: car with tt2's, (stockers going back on)
Last photo:
Join Date: Jan 2002
Location: North of Seattle
Posts: 2,532
Wiki Edits: 0

Thanks: 0
Thanked 5 Times in 4 Posts
Post how do you temper steel?

regarding my clutch linkage @ 5 mo ago, the rod from the pedal to the clutch had to be cut, turned 180 degrees and re-welded. did it, put some beads down it for strength. asked a shop best way to temper they said dip it in oil. i heated it red hot and went to this little room w/a 55 gallon drum full of used motor oil. i couldn't get myself to stick that glowing hot rod in there. went to my shop, heated it again, sprayed cutting oil on it and POOOOF!! IT IGNITED! flames and all. then the guy said to bake it for 30-45 minutes in my oven so i did. it's been 3 weeks every day with a stiff clutch and no bending, but i wonder 1-what would have happened if i would have stuck that in the 55 gallon drum (3/4's full) i wouldn't be here would i?; and 2- why the hell couldnt i just have dipped it in water? so what is the best way to temper steel anyway?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-19-2002, 05:13 PM
willys36@aol.com's Avatar
Hotrodders.com Moderator
 
Last wiki edit: How to rebuild a Rochester Quadrajet 4MV carbureto...
Last journal entry: How to change auto shift timing on 200R4
Last photo:
Join Date: May 2002
Location: Bakersfield
Posts: 8,393
Wiki Edits: 21

Thanks: 1
Thanked 8 Times in 8 Posts
Post

You can only temper steel with high carbon content. Mild steel doesn't have enough carbon content to be hardenable. What you are doing is modifying the shape, size and chemical composition of carbon/iron crystals in the steel and it is a complicated process.

The Whole process includes the all steps you mentioned. The actual recipe is dependent on the type of steel, hardness and toughness you want etc. There is no simple one size fits all formula. What is good for one steel is death for another steel.

In general the first step is to harden the steel. It is heated to "red hot" which puts the carbon in solution with the iron. It is then quickly quenched which solidifies the carbon/iron crystals to a very hard substance. The crystal size is very small, thus a potential crack path is very available. It is so hard that it is very brittle and would easily break. Oil is used instead of water because water is so efficient in removing heat that it could induce so much stress in the steel that it would crack on the spot. Dipping the red hot part in oil wouldn't ignite it but it will smoke a lot. You caused ignition but supplying air, heat and fuel with your fine spray. Dipping the part denies the air thus no ignition.

Obviously the steel left in this condition is not of much use because, although it is very har, it would easily crack and fail under moderate loads. Thus it must be toughened by tempering it with another heat treatment. The part is reheated to "straw color" (a polished surface on the steel turns a yellowish color which is far from blue or red hot. If it reaches blue, the hardening is ruined and must be repeated). The steel is held at this temperature for several minutes which changes the chemistry to a slightly softer but much tougher chemical composition and allows the crystals to grow thus reducing the availble crack path.

That is a much simplified description of the process but is what must be done for a reliable part.

I do a lot of heating and bending of of steering parts but I never quench the part but let it cool very slowly. This leaves the part that is still plenty strong with tough large crystals that will bend before they catastrophically crack. If you did some welding, you induced some very bad localized stresses and poor grain structure around the weld bead by creatign the hard high carbon crystals, especially if you quenched the part in water. NEVER QUENCH IN WATER for anything but mild steel. You will invariably create a virtual piece of glass that will shatter under a certain load. For the relatively low loaded, low safety risk clutch rod, I would remove it, heat it to near red hot then let it cool in still air to room temperature. This will perform the tempering step and relieve the localized stresses around the weld. It is probably several times stronger than it needs to be to bend under the loads it will see in service.

As you can imagine, there are people who make very good careers doing nothing but perfecting heat treating methods.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-19-2002, 05:29 PM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 5,091
Wiki Edits: 0

Thanks: 2
Thanked 112 Times in 90 Posts
Post

Willy your not a machinist by any chance are you? Few people outside the profession have as good a grasp on the technique and actual process of hardening. Good description.
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-20-2002, 02:28 PM
Kevin45's Avatar
Just one of the guys
 

Last journal entry: Garage Toys
Last photo:
Join Date: Jul 2002
Location: Urbana, Ohio
Age: 58
Posts: 3,060
Wiki Edits: 0

Thanks: 1
Thanked 17 Times in 17 Posts
Post

Willy,
Quenching steel in oil WILL produce a flame if it is not completely submerged. Where I work I heat treat smaller tools on almost a daily basis. We have a 35 gal. drum of quenching oil. The newer guys are afraid to put it in the oil so they go slow. WHOOSH!!!! Flame up. I get a kick out of it every time. Luckily they do not lean over the barrel when they do it or a few eyebrows would be lost. The key is to submerge it quickly and move it around. Then after completely cool we clean it and draw it back to a light straw color. This will temper it without breakage. This is for oil hardened tool steel though. Air hardened is a different process. There are different processes for different steels..

Kevin
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-23-2002, 04:09 PM
bullheimer's Avatar
NEVER use credit cards!
 

Last journal entry: car with tt2's, (stockers going back on)
Last photo:
Join Date: Jan 2002
Location: North of Seattle
Posts: 2,532
Wiki Edits: 0

Thanks: 0
Thanked 5 Times in 4 Posts
Post

well thanks, i think i'll stick to the air dry method. being the big puss that i was i would have stuck it in slowly (lets' not go there) and fried my face off! so if anybody comes back, what good or harm did baking the sucker in the oven for half an hour do? it was several hours later when i got home. thanks everybody. great knowlege!!
any big dif btwn used motor oil and quenching oil other than the gasoline content?

[ September 23, 2002: Message edited by: bullheimer ]</p>
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-23-2002, 10:28 PM
RAW's Avatar
RAW RAW is offline
It is now Saturday, everyday!!
 

Last journal entry: Project '57 Ranchero
Last photo:
Join Date: Jul 2002
Location: So. Calif.
Age: 70
Posts: 181
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

Willey36,
Thank you for that description. I have thought about my split wishbones at every ugly bump and the re-forming/quenching the perches for the spring set up. It has been 12 years but can't wait for that IFS installation. r
__________________
Looking for the right '57 Ranchero for a "keeper" this time.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-24-2002, 06:29 AM
deuce_454's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Copenhagen, Denmark
Age: 39
Posts: 1,000
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Post

willys, i am sorry to say this but you have some of your metalurgy facts wrong, you talk about putting the carbon in solution.. well thats very well with cast iron, that have a carbon content of more than 2 percent and actually have free carbon deposits within the metal matrix in either flakes (grey cast iron) or in spheres (nodular cast iron) but there is NO free carbon in steel,

that is the difference between cast iron and steel which has a carbn content of under 2 percent and thus have all the carbon bound as carbon atoms dispersed within the iron atom crystal structure.

what happens when steel is tempered or hardened is that the crystal structure undergoes a conformational change at temperatutres above arround 750 celcius, when the steel is cooled the crystal structure changes back, but this requires energy and the speed of the rearangement is governed by the content of among other things carbon, other elements like crome, vanadium, nikkel and many others will have a simmilar effect either speeding or slowing this process up or down.

as mentioned above the reconformation requires energy and when the speed of the is limited by elements in the alloy, and the temperature is dropped quickly the conformatinal chande is halted giving a brittle structure called martensite, now to the anealing

anealing is a process that allows the martensite to rearrange into a more ductile structure which is why bullheimer was told to put the part in the oven to aneal the martensite and yield a part with a higher yield strength but less brittle.

and lastly to the cooling process, cooling in oil is a more controlled or slower cooling process than cooling in water and thus is less prone to introduce cracks and warp the part.

but the quenching in water is sometimes nessacary to cool quick enough to stop the rearranging into the weaker alfa-structure iron. but it males anealing very nessacary, so quench and aneal at what ever max temp your citchen oven allows, and leave it in for 3-4 hours as this process takes time.

hope it helps

ps.

as you might have guessed i mave a degree in mechanical engineering so i just had to reply
(anyone by the way know how you can tell how you are an engineer? its when you have no life, and can proove it mathematically)

[ September 24, 2002: Message edited by: deuce_454 ]</p>
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-25-2002, 12:22 PM
Madd Syntst's Avatar
Returning American Maddman
 
Last photo:
Join Date: Apr 2002
Location: Boynton Beach, Fl
Age: 61
Posts: 444
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

Thank you professors! God I love this place. thank you guys for once again having more information than I can comprehend, but I love to learn this stuff!
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-25-2002, 04:41 PM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 5,091
Wiki Edits: 0

Thanks: 2
Thanked 112 Times in 90 Posts
Post

<img src="graemlins/drool.gif" border="0" alt="[drool]" />
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-29-2002, 08:18 PM
bentwings's Avatar
bentwings
 
Last photo:
Join Date: May 2002
Location: St.Paul, Minn
Age: 72
Posts: 1,798
Wiki Edits: 0

Thanks: 0
Thanked 16 Times in 15 Posts
Smile

duce 454,

thanks for the clarification. I too am a sr. mech. engineer. There is a lot of mis-information published to the hotrodders that could get some in serious trouble.
Heat treating is one and welding is another. For the most part if you have to ask how to heat treat a steering part or weld on a primary part of a car you should (must) get pro help. There is nothing like loosing a wheel spindle at highway speed. You may be in serious legal trouble if you hurt someone too. I see a lot of parts modified by welding and various mythical heat treatment ideas that simply don't wash. I've seen a spindle that was welded and "heat treated" go 'pop' on the bench and be in two pieces. Imagin that while you are tooling around. Buy the good stuff, pay a little extra and be safe. We want everone to keep posting.
My little project was a pair of rear axels for my junior fuel car back in the late 60's. I worked in a very large machine shop (as apprentice and journeyman) I carefully cut the axels and prepared them for welding. The heat treating dept helped me design the joint and I used my welding skills to Tig weld them then promptly heat treated them. The long of it these axels lasted 2 years of running 80% nitro. then I got rid of the alcohol and "ran the can". They lasted about another month before one broke taking the motor with it. The axel had a full turn of twist in it!! And it did not break in the weld nor near it. It's possible we could have toughened them a bit more but for stock type axels they paid for themselves and I bought new specialty axels and had no further problem. If you were to try to do this today it would cost more to do it yourself than the new axels would and not be as good, as the steel in axels is some pretty tough stuff.
anyway just be carefull when you modify parts by welding, heat treating or machining. At the minimum ask a no life engineer. we eat, live, sleep and enjoy churning numbers just for the fun of it.
P.S. as for proving it just look at my check book. 0 times all the fun in the world is still 0.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 10-02-2002, 07:06 AM
willys36@aol.com's Avatar
Hotrodders.com Moderator
 
Last wiki edit: How to rebuild a Rochester Quadrajet 4MV carbureto...
Last journal entry: How to change auto shift timing on 200R4
Last photo:
Join Date: May 2002
Location: Bakersfield
Posts: 8,393
Wiki Edits: 21

Thanks: 1
Thanked 8 Times in 8 Posts
Post

Yes, I realize my explanation was quite styleized but I thought if I got into talking about martensite and austenite and utectics of various steel formulations, people would have gotten more bored reading my post than they already were.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 10-03-2002, 03:37 PM
bullheimer's Avatar
NEVER use credit cards!
 

Last journal entry: car with tt2's, (stockers going back on)
Last photo:
Join Date: Jan 2002
Location: North of Seattle
Posts: 2,532
Wiki Edits: 0

Thanks: 0
Thanked 5 Times in 4 Posts
Post

okay, so i know to quench, then anneal. and anneal in the oven at max for 3-4hours. but i'm still wondering if water is good or bad. is dipping in water preferable to nothing at all? and what is going on when people drop hot parts into a bucket o'cold water? i aint no engineer. but i have here two conflicting ideas on water quenching and i have to be honest, there aint no way im stickin a red hot poker in that 55 gallon drum of used motor oil till i see it done in person from 50 feet away!
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 10-03-2002, 05:02 PM
willys36@aol.com's Avatar
Hotrodders.com Moderator
 
Last wiki edit: How to rebuild a Rochester Quadrajet 4MV carbureto...
Last journal entry: How to change auto shift timing on 200R4
Last photo:
Join Date: May 2002
Location: Bakersfield
Posts: 8,393
Wiki Edits: 21

Thanks: 1
Thanked 8 Times in 8 Posts
Post

As I mentioned in my first post, there is no one recipe for heat treating high carbon steel but IN GENERAL, quenching in cold water is bad. It cools so quickly that the grains are left as martensite which is extremely hard and brittle and the grains are very small which leads to crack formation. If you are bound to do heat treating yourself, I would vote for cooling in still air. The part at least will be tough (bend before breaking) instead of catastrophically snapping in half.

[ October 03, 2002: Message edited by: willys36@aol.com ]</p>
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 10-03-2002, 05:23 PM
hotrodit's Avatar
Member
 
Last photo:
Join Date: Jun 2002
Location: U.K.
Posts: 92
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Talking

Willys can i be you! cos i know where you'll be for the next three days. <img src="graemlins/drool.gif" border="0" alt="[drool]" /> :p
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 10-04-2002, 02:49 AM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 5,091
Wiki Edits: 0

Thanks: 2
Thanked 112 Times in 90 Posts
Post

Some tool steels must be quenched in water to harden, some steels should be quenched in oil for the same effect.

As a matter of interest you can buy two different types of drill rod, O or W. O is oil hardening and W is water hardening. If you try to harden O rod in water it can crack, tempering is done to toughen the steel and improve the structure. If you try to quench W rod in oil you will end up with an poorly hardened piece that will have excessive grain growth (large grains) and a brittle part with no strength.

Annealing is done to make a part dead soft, tempering is the next step in heat treatment after quenching to "bring back" some of the toughness to the steel and reduce hardness to a desired level. All fully hardened steels must be tempered or risk internal stresses causing internals cracks which eventually will cause complete failure. You can think of the tempering process as reorganizing/refining time for the molecules of ferrite and carbon to find a crystal structure that is stable.

Having face centered or body centered cubic structures determines the ultimate strength of the molecular bonds between adjacent atoms in the structure. As steel goes through heat treatment the steel bonds will go through these atom arrangements and ultimately a mix of the structures is what is desired with the finest grain sizes possible.
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message

Recent Hotrodders' Lounge posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 08:42 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.