How to tell a cast axle to a forged axle

I want to say that we have to "toast" suspected hydrogen embrittlement plated parts at some "low temp" over a "decent time" in no more than a "kitchen oven", BUT I may be way off here???

It's been years since I looked into this is all.........

pdq67

 

Hi Deuces, Sorry it's taken me so long to reply, it's probably just as well as the posts are turning a bit 'brittle.'

The Emerald City is as always sparkleing in the sunlight. Despite their best efforts the Property Developers, Urgers, Sharks, Bent Pollies and other bludgers of nefarious intent, havn't managed to completely stuff it. But the stain of the Rum Corps runs deep, and the old rorts never change.

Port Kembla has changed, 'Big Harrys Place' has cleaned up their act and built new Blast Furnaces, people can actually breathe the air now. You'll find it hard to believe but the little Miners Cottages than line the cliff tops around Bulli, Coldale, Scarbough etc are now fetching the same price as houses in Sydney. Everyone wants a waterfront home and you can't beat the view from those wee shacks. The pollution is gone from the beaches and the old Kembla is mostly gone, it's quickly being replaced by the new beaut modern Sydney replica.

About time you came back for a 'Captain Cook.'

 

Wouldn't 'ductile' and 'malleable' be two different species? Anyway, these axles are cast steel not cast iron... big difference.

 

That's the way your statement reads.

...again, we need proof.

 

I would'nt use cast, I can find forged axles laying in the weeds still. Who want's doubts while driving your car or truck?

 

Plated parts need to be baked within
a couple hours of plating, to remove any Hydrogen.

NOT practical to do at home.

 

Do some research on Hydrogen Embrittlement.
Parts can fail under load.

 

Sure they can. I know that. I also know about HE. You guys are missing my point. I'm talking about axles here. A picture of a broken AXLE. That's proof. I'm not taking anything else as proof but a photo. With all of the talk about it, you would think that someone has a picture of one... yet no one has posted a picture of an axle failure.

 

Sure you can reference it back , to ASTM , ACI, UNS, AISI ,we do it all the time. You just use the equivelent chemistry required and mechanical properties needed.
Most cast steel is molded in Green sand ( least expensive) No Bake type ( Resin setting sand ) Perm. Molding etc. etc.now days.
Investment cast or lost wax( 2 different animals depending on the binder used to hold the coating sand together) is also used but more expensive and usually for smaller , more intricate parts.

I agree as a general term forgings are stronger than a "cast " part but not all part designs lend themselves to the forged or wrought process.

 

Here is a pic of a broken axle, it is borrowed from another site covering an accident so this axle took a heavy impact blow.
However the fact that is chromed may have contributed to it breaking, plus the fact that it more than likely cast.

I have a friend who works in an aviation anodizing shop and they have to cook all their parts to protect against hydrogen embrittlement. It is only a fairly low temperature cook, but seems to be very important to maintaining the integrity of the item.
How soon after or how long before this cooking needs to be done, well I never knew to ask.

In the kind of accident above I guess it would not really matter what axle was used, since there is no hope in hell that you would expect to reuse something that had taken such a hard hit all be it bent or broken.

It is those low impact hits which are the scarry ones, where a forged axle would remain intact but a cast axle could break and cause more serious consequences.
For example running out of control and hitting something even worse.

After saying all that, I guess we will never know if the axle in the pic actually broke first which then caused the greater accident as we see it now.

 

HE statement from our metal dude:

07-21-2008, 01:16 AM #7
38Chevy454
Alliance Member




Join Date: Oct 2001
Location: Tijeras, NM (Albuquerque)
Posts: 2,412 Re: Baking new chrome plate?

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Quote:
Originally Posted by toddc
I get stuff plated at work. Mainly ferrules for hoses. They are made from 1020 ~ a very soft steel. Trying to find a plater at all here is difficult, let alone a good one. Anyway, I reject about half of the batches from the platers because they crack.
Embrittlement CAN happen in soft steels!

And yes, the baking needs to be done very soon after plating.

http://en.wikipedia.org/wiki/Hydrogen_embrittlement

HE is very hard to cause problems if the steel is not hard enough. Your "soft" steel is probably work hardened due to forming and is not in fact "soft" anymore. But I will not argue, your results show that you have cracking of some type.

BTW, any plating operation cause hydrogen to be produced at the metal surface of any hardness metal, some of the hydrogen gets diffused into the metal. But it is only a problem if the steel is susceptible, which is generally considered to be ones that are above Rockwell C 30. However any plated part has hydrogen increase due to plating, it just does not cause cracking.

Also HE is a problem with parts that are under sustained stress loading. Not for small time period loads. A part with real bad HE will crack and fail within 8 hours or less. The typical test for HE is to stress the part to 90% of yield and hiold for 72 hours. Any failure out of the sample lot (say for dicussion 10 pieces) would reject the entire lot. A part with HE that is not under sustained load will not fail by HE.

A plated part that fails after many years is not from HE, but would be most likely from fatigue cracking. People always see a failed plated part and then blame HE as the cause, even though the part was in service for 5-20 years or more. This is not HE, remember above that HE will fail quickly under sustained stress.

You can bake any plated part, no matter what condition the steel is on. Sooner the better right after exiting the plating bath is best. Post bake polish will bring it right back to shiny, the oxidation is minimal.
__________________
I used to have a handle on life, but it broke....

 

Good points.
Your post configuration was a little confusing though.
Maybe worth editing out the stuff from the board.

 

Yeah...picked up a lot of extra somehow. Also have found a pithier stement from '38...

 

That's weird because my cast iron 455 Olds crank rings if I tap it...

 

Here, more compact statement from same source:
38Chevy454
Alliance Member




Join Date: Oct 2001
Location: Tijeras, NM (Albuquerque)
Posts: 2,412 Re: I-Beam Dropped Axels - forged vs cast, dudctile iron

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Oh man, some bad info here. Let me present some facts. Hydrogen Embrittlement (HE) has the following characteristics:
1. Only affects high strength steel, generally considered Rockwell C 30 and higher.
2. Any acid processing can cause the HE, although plating is the most common source.
3. Baking after plating is best when done soon as possible, but many requirements state within 4 hours.
4. HE does NOT make the steel weaker.
5. HE does cause a crack to form and the piece fail, the crack is the failure, not the strength of the steel.
6. HE will only cause failure if you have some sustained stress on the piece. Sitting by itself on the shelf will never fail by HE, must have an applied load.
7. The applied load has a threshold value that is dependent on the level of hydrogen and the strength level of the piece.
8. HE is also not 100% in a given lot, but only a fraction that fails by HE makes the whole lot suspect.
9. Typical HE test is to load the piece up to 90% of yield strength and hold for 72 hours. If you have HE it will fail within this period.
10. HE is not a delayed fracture.

Please consider these as the facts and apply as appropriate to your situation. It is intended as informative and not critical.

 

Eyewitness accounts suggest this axle failed right before the car crashed:
http://www.volksrods.com/forum/showthread.php?t=30628
" A friend that was following said that it looked like the car dropped on the right front and left the road."

 

Can you supply any details on who is manufacturing or selling Cast Steel axels.
While I have a natural bias toward Forgings (being a blacksmith) I would sooner trust a ductile/malleable cast axel than a cast steel axel.

Spheroidal Graphitic Irons also known as ductile and malleable irons are typically used in stressed parts, where higher strength is required, and is currently used for reproduction axels. The composition and characteristics of the iron allows some flexibility while in use, however, over many thousands of flex and stress cycles I would put my money on the forging.

IMO the wisdom of using cast axels is questionable, as in all things, price for most people is a significant factor in the choice of parts.

 

There was a famous picture in Street Rodder taken on the way to the Peoria Nats...It was Willie Black's black '29 Roadster, pictured on the side of the turnpike with a broken aftermarket tube axle. (anyone remember Willie's license frame "Black is Beautiful"?
Cause was hydrogen embrittlement, which launched picture stories of the phenomenon in R&C, Street Rodder, and Rod Action. (this was previous to 1982, and there was lab ****ysis performed and reported in the articles, so it was a legitimate concern)
Willie was the painter of the Bud Bryan R&C '29 Highboy, and many of Magoo's highboys; a Major Player. No one was injured, and the Minnesota Street Rod ***ociation ***isted with repairs at the Nats...
BTW, how could you doubt mountains of evidence of hydrogen embrittlement? It's been an accepted problem for 50 years.

 

I just read the thread. Sounds to me that it's debatable if it broke before or after it hit the tree. More likely in my mind that the perch bolt broke first causing the car to drop...

 

...again, I'm talking about a broken I-beam axle (chromed, dropped or aftermarket) that did not take a hit. I've never seen a picture.

 

It it rings it's probably steel, if it goes thunk it's probably iron.

 

Another can o' worms...perch bolt. Stock forged, streetrod cast...some are even cast stainless.

 

Damn, I'm happy with my choice of original forged Ford parts on my front end.

 

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