Hydrogen embrittlement

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Hydrogen embrittlement

This topic has 20 replies, 10 voices, and was last updated 22 December 2009 at 00:47 by Ian S C.

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18 December 2009 at 03:46 #4885
GoCreate
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@gocreate
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18 December 2009 at 03:46 #46370
GoCreate
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@gocreate
Hi

Many metal finishing processes add hydrogen to the material, for higher strength materials I think above 1050 N/mm2 tensile require the hydrogen absorption to be released through heat treatment within a specified time period. With out the heat treatment tramped hydrogen causes the material to become brittle, the component can fail at a fraction of it’s normal capability.

Does anyone know if hydrogen embrittlement can be a problem with black phosphate coating? I think any phosphate coating adds corrosion protection by converting the surface of the material bugt is hydrogen absorption take place?

Maybe hydrogen embrittlement should be a safety alert subject for those not experienced with the effect various processes have on materials. I heard of a case where someone anodised an aluminium aircraft part and because of it this highly stresses part failed.

Thanks

Nigel
18 December 2009 at 10:27 #46373
Ian S C
Participant
@iansc
I did mention a warning on another site about hydrogen embrittlement in relationship with electrolitic rust removal on high carbon steel,I first encountered it in spring steel.I’v forgotten the temperature,but cooking the item for a number of hours is worth trying to over come the problem.Ian S C
18 December 2009 at 11:01 #46376
mgj
Participant
@mgj
Anyone who is phosphating or anodising or electroplating will de-embrittle as required.

If its an electrolytic process the possibility is there. This is a very well known phenomenon so I doubt its something to worry about, unless one is going to DIY.

As a matter of interest, just following from your earlier posts about the Burrel – was this to do with that project?

Edited By meyrick griffith-jones on 18/12/2009 11:02:06
18 December 2009 at 14:19 #46381
KWIL
Participant
@kwil
As I recall metals and hydrogen “come off” at the cathode, hence as we know, ANODISING is the action of oxygen with the aluminium to form the oxide coating which the basis of the anodising process. No embrittlement here.
18 December 2009 at 17:58 #46385
GoCreate
Participant
@gocreate
Hi everyone

Ian – I seem to recall the de-embrittlement temperature is around 190 deg C and has to be done 4 to 6 hours after the coating process and baked for several hours. If not done in the required time span hydrogen becomes permanently trapped and the heat treatment does not work.

Meyrick – It’s actually a 3″ Allchin I am building but a Burrell is close enough. The parts in question are for a motor cycle restoration project being done by a freind, he gave me some large socket head cap screws (probably 12.9 grade material) from which to make the parts and wants to get them black phosphated. It occurred to me that with this material hydrogen embrittlement might be a problem.

Kwil – I did not mean to infer that hydrogen embrittlement is a problem with anodising, only that by treating the component surface the load bearing capacity was effected. I think perhaps the anodised surface in less ductile and more susceptible to suffering a minute crack under certain loading conditions from which a larger crack may propagate especially in a cyclic loading condition, only my guess.

I conclude that de-embrittlement is a safer route just in case. At 190 degC it can be done in a domestic oven.

Thanks for your helpful comments

Nigel
18 December 2009 at 19:25 #46386
V8Eng
Participant
@v8eng
I find that using the domestic oven for engineering purposes is best done when the authority is out for the day!

Remember not to leave oily marks on it, put nothing nasty or smelly in, and last of all make sure it cools down before they get home (unless you’ve cooked dinner afterwards).

Lessons in domestic bliss are best learnt very early.

Edited By V8Eng on 18/12/2009 19:31:16
18 December 2009 at 19:51 #46387
David Clark 13
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@davidclark13
Hi There

How do you get her to go out on her own for a day.

30 years and I have not managed that yet.

regards David
18 December 2009 at 21:02 #46390
Martin Cottrell
Participant
@martincottrell21329
David,

That has to be quote of the month!

Regards, Martin.
18 December 2009 at 21:26 #46391
mgj
Participant
@mgj
Nigel – I thought you were going to get it done for the TE, and I thought it a bit dedicated as a pre- painting process.

Give it to the experts – they’ll do the whole shebang, dewatering, the lot . This is zinc phosphate I take it. Tell them what the end use is and let them sort the process. You can manganese? phosphate aluminium as I recall. HT bolts certainly fall into the region where de-embrittlement is necessary, and doing bits of racing car, we got everything done.

As a matter of interest, I don’t think you anodise steel do you – there are so many different processes these days who the hell knows. Steels I think are plated and passivated, but there is clear passivation (which is often mostly blue!) and all sorts.
18 December 2009 at 21:28 #46392
Billy Mills
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@billymills
Hi Hi There,

Invest in a trip down to the NEC for a two day Craft/Cookery/Dressmaking/Knitting exhibition for her and a friend then enjoy your shed time.

You might get extra fringe benefits like a nice knitted cover to keep your vertical mill warm, or a natty new pinny/manly overall to show off with.

It is possible that your attendance might be compulsory in which case you could drop a machine vice on your foot ( you don’t really do this -you could damage the vice- just apply some blue and black to the tootsies) so that you can claim that you can’t walk but you would not want to spoil her enjoyment would you?

The blue and black will rub off eventually. If the plan does not quite work don’t worry too much, Hospitals don’t keep anyone in for long these days.

Hope that helps!

Alan.

Happy Xmas!
18 December 2009 at 21:53 #46397
V8Eng
Participant
@v8eng
Hi.

Guess I’m lucky, mine goes out with a long time friend at least once a month, thats 6 hours (minimum) entirely to do whatever suits me!

I am of course entirely happy with that arrangement, and even enquire what sort of a day they had, listening politely to the answers, of course this tends to distract.attention away from my own activities but if she asks the answer ‘just doing odd things in the workshop’ seems to be ok.

Edited By V8Eng on 18/12/2009 22:01:17
18 December 2009 at 22:07 #46398
GoCreate
Participant
@gocreate
Hi Everyone

Thanks for your kind thoughts and advice, It’s very simple, I can take advantage of this time of year. A wad of cash and instructions to her in-doors to go and buy my xmas present, I will tell her I want a set of smooth faced straight curved safety spiral tanged files, then her in doors will be out door for a good while and I will just have to be dis-appointed on xmas day. I need to act fast though, time is running out.

The only problem is, I will need to ask her for a cash advance to have the cash to give her, as it’s for my pressi I am sure she will oblige. No problem.

Nigel
19 December 2009 at 01:03 #46402
Martin Cottrell
Participant
@martincottrell21329
Hi Nigel,

I have a nice system going which works pretty much all year round. All you need is a teenage shopaholic step-daughter who can’t drive, a wife who can drive (?!) but can’t map read & a sat-nav preprogrammed with a choice of at least 4 different city park and ride sites. Just bundle all 3 into the car select a destination & wave them off! I’ve chosen Exeter, Bath, Bristol & Cardiff as my destinations of choice as each one is at least an hour away and contains plenty of shop things to keep them happy for a day!

Back to the topic, with the women out of the way you can turn on the oven, bung in your anodized doo-dahs to purge the trapped hydrogen along with a nice large baking potato for lunch and whilst that lot is cooking disappear into the workshop & wait for the smoke alarm to warn you that lunch is cooked. Who said men can’t multitask, eh??!

Regards, Martin.
19 December 2009 at 09:34 #46407
Ian S C
Participant
@iansc
Stick it in the oven with the Christmas roast,should be a wee corner you can put them.Ian S C
19 December 2009 at 11:37 #46414
Circlip
Participant
@circlip
What a set of damn wimps, you tell her YOU’RE the man of the house so what you say goes! (She told me to put that).

In normal households, (The ones that do Sunday roasts) that’s the day to do the “Blueing” and tempering. Ovens already hot so you’re not wasting energy heating it up and providing you clean your bits (Metaphorically speaking) What’s the problem??

I do wait untill the lunch is cooked before the racks sprout dangly bits of wire with spindles etc. hung on them. Favourite colours (Colors – for the Collonials) are dark blue and purple, quench in gearbox oil (Clean) and allow to drain, – Gas mark or Regulo – Look it up in Tubal Cains “Model Engineers Handbook”

Regards Ian.
19 December 2009 at 11:46 #46415
Richmond
Participant
@richmond
Ian,

This sounds more like a yorkshire household…….. mind you, cant have blue dripping onto your yorkshire pudd being kept warm …. waiting for the jam to be added. *smiles*

If David could actually get the wife to go out he could learn a whole new skill…. operating a new ( domestic ) tool….fail … and then realises he needs to find the manual….. remember, a real “man” reads the manual as a last resort

Ponders whether Ian uses the oven under domestic supervision…. Elfin safety etc etc etc

*grins*
20 December 2009 at 18:49 #46467
V8Eng
Participant
@v8eng
Gentlemen.

I discussed the matter of using the domestic oven for engineering purposes with the leadership many years ago.

After lengthy negotiations the following official edict was issued:-

‘You are not putting your mucky engineering stuff in the oven, we cook our food in there’.

This advice is still the official view, and disobeying it is done entirely at my own risk!

Edited By V8Eng on 20/12/2009 18:56:01
21 December 2009 at 01:02 #46477
Ian S C
Participant
@iansc
You might find an old oven at a garage/car boot sale.Ian S C
21 December 2009 at 21:16 #46510
V8Eng
Participant
@v8eng
Thanks Ian.

Reckon it’s probably easiest to keep using my existing system (see post 6).

Edited By V8Eng on 21/12/2009 21:20:13
22 December 2009 at 00:47 #46516
Ian S C
Participant
@iansc
V8Eng,your right,I,v got no problem (or wife) the ovens there to be used when ever required,if you need it just pop in ha ha,think i might be awee bit far away.Ian S C
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