Author Topic: Heat Treated Steel Finish  (Read 1493 times)

Offline J_Speegle

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Heat Treated Steel Finish
« on: May 20, 2016, 12:09:21 AM »
It was brought to my attention that the use of "Dark Heat Treated Steel" may be misleading some readers/observers to assume that the final finish on these parts was a very dark one. I'm sure one of the scientist on the site could fully explain how the heat treating process changes the metal, improves its strength and all those details but what is most important to us is how it looks or should look on a restored car so I'm focusing only on that. The short version is that these parts are formed them heated and finally quenched/cooled in an oil bath. The oil did a number of positive things for the process and depending on how old and used it was could effect the tone of the finished part.

In judging and restoring we are looking for a visual difference between bare unheat treated steel parts and the heat treated parts rather than the monotone finishes you can sometimes see. Since its the contract that often is the measuring tool it can be difficult to show it in pictures but over the next week or so we'll be posting some pictures to help try and illustrate this difference. In some cases (like spindles, coil and leaf springs) the darker tone will be more noticeable while other steering related parts will be less extreme.

Currently restorers on this site are using the gun bluing repair fluid, phosphating (controlling the amount of exposure time) and some tumbling the parts as part of the process

Hope this helps others now and in the future
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline brennancarey

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Re: Heat Treated Steel Finish
« Reply #1 on: May 20, 2016, 04:07:00 AM »
great looking forward to follow this and the examples that you will be showing us...!! :) :) :)
67 GTA 390 Fastback
Dark Moss Green
Dearborn
Build Date 12/28/66

Offline deathfrog

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Re: Heat Treated Steel Finish
« Reply #2 on: May 31, 2016, 10:07:38 PM »
As you are defining the difference in heat treated vs other...does the year or plant matter? I have read the article on bluing and looked into parkerizing. I read from natural "shiny" to dark gray.I would like to restore these pieces once and would like to do it right.
I used electrolysis to clean the parts. The spindles are a bright silver/gray. The tie rods, idler arm are dull gray with some dark shadows. That is straight out of the electric bath.
I am looking forward to your updates!

Offline J_Speegle

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Re: Heat Treated Steel Finish
« Reply #3 on: May 31, 2016, 10:56:02 PM »
As you are defining the difference in heat treated vs other...does the year or plant matter? I have read the article on bluing and looked into parkerizing. I read from natural "shiny" to dark gray.I would like to restore these pieces once and would like to do it right.
I used electrolysis to clean the parts. The spindles are a bright silver/gray. The tie rods, idler arm are dull gray with some dark shadows. That is straight out of the electric bath.


Since the parts were produced by a ton of different suppliers (depending on part) if you look across all the years there can be some variation but I would report that there is more commonality between the type of part and the original finish than difference. Some of the results may be due to the make up of the metal and its reaction to the batch while the variation can be a result of how fresh, old or burnt the bath oil is.

Some parts can take on a outer coating (for lack of a better term like spindles which are normally very dark in finish if you look past the 65-66 period while no change in surface is seen on steering components such as center link or tie rod ends. I believe that few if any are looking for an exact look (due to the number of variations) but instead a range - much like on other finishes such as sealers, sound deadeners, paint ....... I explain it as if a number of the experienced members here saw the finish and took notice that it "caught their eye" or stood out then its likely outside of the range your looking for


Most restorers have their own method on how to get - some can get pretty creative. As for your description of your spindles - other than the machined surfaces I would not think of them as bright silver unless its those surfaces that you are describing

Thanks for bringing my attention back to this thread  - I need to follow up. Going to be a busy month but will book mark it with one other I need to get back to  :-[
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline FXguy

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Re: Heat Treated Steel Finish
« Reply #4 on: June 01, 2016, 04:12:46 PM »
Was just finishing up a set of leafs and thought I'd post.  Been using a process to create that heat treated spring steel look using a chemical dip that converts the metal surface and produces a finish that varies from an almost charcoal to a gun metal blue.  Results depend on how long its kept in the dip and how vigorously you go after the freshly dipped finish with paper towels.  Once dry finish up with penetrating sealer of choice (B shield, caswell, etc.)  Included before and after pics.

Offline J_Speegle

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Re: Heat Treated Steel Finish
« Reply #5 on: June 01, 2016, 06:18:08 PM »
FXguy looks like you did a good job keeping a consistent finish on such large pieces
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline sanluis09

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Re: Heat Treated Steel Finish
« Reply #6 on: June 02, 2016, 12:55:37 PM »
Was just finishing up a set of leafs and thought I'd post.  Been using a process to create that heat treated spring steel look using a chemical dip that converts the metal surface and produces a finish that varies from an almost charcoal to a gun metal blue.  Results depend on how long its kept in the dip and how vigorously you go after the freshly dipped finish with paper towels.  Once dry finish up with penetrating sealer of choice (B shield, caswell, etc.)  Included before and after pics.


Excellent finish, what specific chemical dip did you used?

Thanks
1965 WW Hardtop, 289-2V, 3-speed manual transmission. Unrestored. Assembled in Mexico on the time frame of: Oct 64-Feb 65.

Offline FXguy

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Re: Heat Treated Steel Finish
« Reply #7 on: June 02, 2016, 06:37:44 PM »
FXguy looks like you did a good job keeping a consistent finish on such large pieces


Thanks Jeff.  I got a piece of black ABS pipe and capped it on one end.  Built a jig to hold it vertically and put the solution in it.  Then stood the leafs in there.  Was able to do half of the #1 leafs at a time.  I did one half, neutralized the solution and rinsed, then did the other end.  Short leafs were done with a single dip.

Excellent finish, what specific chemical dip did you used?

Thanks

Thanks, I used Caswell's black oxide dip.  Springs had been painted so i first hit with paint stripper, then into EvapoRust.  (Took picture of all the paint marks at this point.  there's more than what i show in the pics, but won't add them until after reassembly.)  After that they were bead blasted, they went into caustic soda or detergent to remove any remaining grease or oil.   You have to be careful with the time in the solution, otherwise you can end up with a very dark finish, which is great for phos/oil bolts but too dark for springs.  The first dip usually leaves some residue that is very loosely bonded, which can be removed with paper towels or a scotchbrite.  What's left gets a little darker and more uniform with the application of a penetrating sealer.

-Scott