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 Post subject: Zinc Plating
PostPosted: Thu Sep 20, 2018 2:21 pm 

Joined: Tue Jan 24, 2017 10:32 am
Posts: 77
Hi All,

Looking at the facebook page for the restoration of Florida East Coast # 148, new side rods are shown as having just been cast for the engine. Someone asked what was wrong with the old rods and it was answered that they had been zinc plated while the engine was overhauled at the New Hope and Ivyland in the 70's, and if not done properly, the zinc plating could cause fatigue cracking from making the metal too brittle. If this is the case, why would the zinc plating have been done in the first place? Just to prevent corrosion?

Thanks,
John


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 3:10 pm 

Joined: Thu Feb 27, 2014 10:08 am
Posts: 406
Zinc plating, or galvanizing, is a common method of corrosion protection. The most common method, hot-dip galvanizing, can be an issue with high-strength low-carbon steel because the process introduces hydrogen into the steel which diffuses into the steel and forms bubbles at the metal grain boundaries. These bubbles put pressure on the grain boundaries which decreases the energy required to pull the grains apart and results in hydrogen-induced cracking. Alloys with a tensile strength of about 1000 MPa and greater are the most susceptible. Hydrogen introduced during a plating process can be diffused out by heating the work piece to around 400 F for a few hours. Hydrogen diffusion during welding can be minimized by preheating and post heating. When I was involved in similar work, we used to bake the piece in an inert atmosphere of Nitrogen after fabrication and cleaning.


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 3:53 pm 

Joined: Tue Jan 24, 2017 10:32 am
Posts: 77
Thank you very much!

John


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 3:55 pm 

Joined: Fri Jan 10, 2014 5:00 pm
Posts: 54
I really wonder if the new rods were Cast?


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 4:05 pm 

Joined: Fri Jul 23, 2010 12:41 pm
Posts: 456
Location: Minneapolis, MN
Kimball wrote:
I really wonder if the new rods were Cast?

Side rods are always forgings, never castings. The forging process orients the grain of the steel and makes a very strong and resilient part.


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 4:38 pm 

Joined: Thu Feb 27, 2014 10:08 am
Posts: 406
rem1028 wrote:
Thank you very much!

John


You are welcome. To be clear, I'm not saying that this was the case with 148's rods. I believe the new rods were fabricated at Strasburg Rail Road so Mr. Kelly Anderson may be the best resource for the particulars on the issues with the old rods and certainly is the best source for information regarding the fabrication of the new ones.


Last edited by Scranton Yard on Fri Sep 21, 2018 4:07 pm, edited 1 time in total.

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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 8:55 pm 

Joined: Tue Jan 24, 2017 10:32 am
Posts: 77
Sorry, nowhere did it say that the rods were cast, I used the wrong term due to my lack of knowledge with the subject.Thanks for the tip re: asking Mr. Anderson. My main curiosity was why zinc plating would be applied if it could result in metal fatigue. Was this something commonly done to locomotive rods?

John


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 9:43 pm 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 5529
Location: southeastern USA
hamster wrote:
Kimball wrote:
I really wonder if the new rods were Cast?

Side rods are always forgings, never castings. The forging process orients the grain of the steel and makes a very strong and resilient part.


Glover Machine Works regularly cast side rods for their steam locomotive production.

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Corollary: "He who does is doomed to watch those who don't repeat it anyway."


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 Post subject: Re: Zinc Plating
PostPosted: Thu Sep 20, 2018 9:53 pm 

Joined: Thu May 24, 2012 1:37 pm
Posts: 1073
We had a similar discussion a few years ago about waterjet/plasma-cut rods and whether they 'needed' to be forged to have the right metallurgical characteristics. I took the position that progressive forging rather than selective material removal to near-net-shape was a better method of rod fabrication, but several very prominent (and highly experienced) shop people, if I recall correctly including Kelly, thought that cutting mild steel to make rods was acceptable practice. A decent near-net-shape casting using better modern methods might have the same relative lack of internal flaws/stress raisers as a piece cut from rolled plate away from edges.

On the other hand, the idea of using a general sand casting, unforged, as a rod leaves me worried, no matter how well the surfaces are dressed.

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 Post subject: Re: Zinc Plating
PostPosted: Fri Sep 21, 2018 7:55 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1461
Location: Strasburg, PA
rem1028 wrote:
Someone asked what was wrong with the old rods and it was answered that they had been zinc plated while the engine was overhauled at the New Hope and Ivyland in the 70's, and if not done properly, the zinc plating could cause fatigue cracking from making the metal too brittle.

And here I thought is was because the old rods were worn out, with the holes bored too large, etc. Learn something every day. Also, the customer wanted floating bushing main rods in place of the original split brass rods.

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I didn't see any obvious sign of galvanizing on the old rods, though it is mentioned in an ICS book as a way to prevent rust.

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 Post subject: Re: Zinc Plating
PostPosted: Fri Sep 21, 2018 8:51 am 

Joined: Wed Oct 31, 2007 10:40 am
Posts: 84
Location: Chama, NM
Kelly Anderson wrote:
Also, the customer wanted floating bushing main rods in place of the original split brass rods.

Is there a particular reason for staying with the split brass on the small end?


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 Post subject: Re: Zinc Plating
PostPosted: Fri Sep 21, 2018 9:32 am 

Joined: Tue Jan 24, 2017 10:32 am
Posts: 77
Thanks for setting the record straight Mr. Anderson.

John


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 Post subject: Re: Zinc Plating
PostPosted: Fri Sep 21, 2018 2:43 pm 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1461
Location: Strasburg, PA
Russ Fischer wrote:
Kelly Anderson wrote:
Also, the customer wanted floating bushing main rods in place of the original split brass rods.

Is there a particular reason for staying with the split brass on the small end?

My main reason was because that is what the customer wanted. I expect because of wanting to have some adjustment in length.
rem1028 wrote:
Thanks for setting the record straight Mr. Anderson.

Mr. Anderson is screwing up Amtrak. I’m Kelly

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"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."
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Strasburg Rail Road Mechanical Department


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 Post subject: Re: Zinc Plating
PostPosted: Fri Sep 21, 2018 4:18 pm 

Joined: Thu Feb 27, 2014 10:08 am
Posts: 406
Kelly Anderson wrote:
Mr. Anderson is screwing up Amtrak. I’m Kelly


And here I thought that the questionable policies coming out of Amtrak lately were due to the fact that the guy in charge was only just moonlighting from his (all) day job on the SRR and so he was severely sleep deprived. Thanks for the clarification on that - I edited my post accordingly. Since there seems to be some question in this thread as to the fabrication procedure, can you please go over how the rods were processed? Thank you.


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 Post subject: Re: Zinc Plating
PostPosted: Mon Sep 24, 2018 11:02 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1461
Location: Strasburg, PA
Scranton Yard wrote:
Since there seems to be some question in this thread as to the fabrication procedure, can you please go over how the rods were processed?

The previous discussion on whether to forge or not to forge was here.

The ICS book Rod, Wheel, & Pin Work (1929) says the following, "Main rods are forged from alloy steel billets, such as carbon vanadium or nickel, to a shape that resembles roughly their outline, or billets may be flattened out to a little more than the thickness of the rod, and its outline is then cut out with a cutting torch. This is better than forging the main rod to shape, because it can be cut out more nearly to its approximate size and less time will be required for milling."

These rods were flame cut from 1045 cross rolled plate, then annealed.

A local job shop has CNC horizontal boring mills large enough to mill the entire length of the main rods in one set up, a huge advantage. We calculated what was needed based on Baldwin Standard Practice, and made 3D CAD drawings of each part. We sent a paper copy of the drawings to the sub-contractor, along with dxf and step files of the CAD virtual parts.

Here are some photos.

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_________________
"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."
C. S. Forester

Strasburg Rail Road Mechanical Department


Last edited by Kelly Anderson on Mon Sep 24, 2018 1:16 pm, edited 2 times in total.

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