Different Steels

[ChrisHParticipant @chrish]

Eddie,

 

That’s great – many thanks,

 

Chris

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

The main problem with black bar in recent times is that a lot of it is now imported from dodgy mills in dodgy countries where quality control is unheard of . In the particular case of black bar the rolling process should stop before the bar cools below the temperature at which the true hot rolling process – effectively forging – stops . Some of these dodgy sources just keep on rolling until the required size is reached . So any one piece of bar will have been both hot rolled and cold rolled – taking it into a no mans land where material properties could be anything and certainly variable across the section .

 

I would expect there to be a size effect in this – bar in the middle sizes might be mostly ok but smaller and larger bar would probably show more problems .

 

There is no way to restore badly rolled ‘hot’ rolled bar to its proper spec. – short of melting it down and starting again .

[John Wood1Participant @johnwood1]

Cor, it’s all a bit highbrow. Now in my ‘last-word-in-technology’ workshop (?) I just buy whatever is marked ‘BMS’ for turning and either HSS or silver steel for toolmaking, it seems to work – most of the time! I expect I will come a cropper somewhere along the line.

 

Good information though guys and all noted in my little black book for future reference.

 

All the best

John

[mgjParticipant @mgj]

I must amit, I have always found black bar a bit of a pain to get a decent finish on, and it can tear like hell milling. Of course it can be done with a slightly rounded nose tip lower feed rates, and lower cutting speeds on a mill. But why bother, since for our purposes 220M07 is out there in copious supply. (And its ANSI equivalent for hte rest of the world)

 

You can of course use one of the general engineering steels if one wants to, but the chances of actually needing to are such that unless one actually can calculate stress and strain, and terms like Youngs Modulus and Poissons Ratio actually means something, one wants to stay away from such critical design.

 

Perhaps I’m fortunate – I ask my people for 220/230 M07, and thats what I get. It machines beautifully, it silver solders easily, and it welds just fine, using Argoshield 5 as a gas. And it case hardens fine well too with Kasenit, for crankpins and other such items – I was going to say heavily loaded, but the stress is actually very low.

 

If I ever want to stress relieve it and normalise to black bar standards, then I could – but for why exactly?

 

We, making models of locos generally want adhesion, and that means mass, so slim and lighweight highly stressed structures are not generally our thing. And if they are one’s thing, gererally one will know about it., and be able to do the maths to enable their use.

 

To give you an idea – Metre Maid with 1.5″ cylinders running at 80psi. You get a mighty 140 lbf of thrust.  onto the driving crankpins. Do the sums of load by area on 1/2″ dia pins  in single shear, and you are struggling to make 3/4tonf/sq in. Whats the yield of 220M07 – 12tons or so, UTS at 20-24 tons. Havent looked it up  but it will be in that range.  Not even beginning to stretch it. You are not even in the fatigue range. 

 

 

Edited By mgj on 31/01/2011 21:40:29

Edited By mgj on 31/01/2011 21:53:00

[NilochParticipant @niloch]

mgj – welcome back – again!

[Martin WParticipant @martinw]

Hi mjg

 

Been missed great to have you back again .

 

Best regards

 

Martin

 

PS  Sorry about the smiley !!

Edited By Martin W on 01/02/2011 00:56:16

[mgjParticipant @mgj]

Thanks gents. been doing some serious building.

 

Smiley is fine Martin.

 

Chris H. If you want to know about the composition of steel, and how carbon content affects tensile stregth, and how the disposition of that carbon can radically alter properties, then Tubal Cains Hardening and Heat treatment is as good a book as any.  He’s pretty good on the basics of metalurgy in stell, and the effects of carbon content on the crystal structure.

 

The point is that some alloys are not heat treatable, and some can alter properties radically, and that such properties are altered by very small % of carbon (mostly) and other alloys. But, but is one much interested  in a long list of alloying contents, such as say silica which is added to act as a welding flux?  And does it make any difference to most of us to know that EN XYor Z is a .2 or some other % steel.  UTS and yield perhaps, if we are designing is about as much as we want, unless there are very specific points to the application, like fatigue, temperature and so forth.

 

BTW the old EN designations and current euro numbers are in  TC Engineers Handbook for the normal range of steels of machining steels.

 

What do most of us do with our steel. We chomp it into a shape which is probably highly unstressed, so you could use monkey metal and get away with it (we do in the form of cast iron), and occasionally it forms a sliding surface so we case harden – and by adding carbon to the surface and quench hardening, we could have started with the proverbial monkey metal, but we still end up with a glass hard surface on a soft matrix.  True some steels are better for hardening than others, and leaded free cutting is not a great case hardener, but it will take a shallow case, and thats good enough isn’t it. 

 

Edited By mgj on 01/02/2011 06:25:55

[ChrisHParticipant @chrish]

Hi mgj,

 

My query was prompted by the article in the latest edition of MEW by Harold Hall and his manufacture of lathe fixed/travelling steadies.

 

For the frames and clamp plate he specified 230M07 and for the base 070M20; I was wondering what the difference was and if the base was made of 230M07 what would be the likely problems.

 

Looking at most – well, at least some – of the suppliers of steel for model engineers, the general steel available seems to be 230M07; not many, in fact I don’t think I have come across any, that do anything else, hence also the query. Perhaps I am looking in the wrong place.

 

I am not really too bothered in reality what the chemical compositions are, I was just searching to satisfy my curiosity. If I eventually make a fixed steady to suit my lathe, which is old and in all probability a ready made fixed steady could not be found, I shall probably make it all in 230M07 – the whole steady would I guess be very lightly loaded.

 

I now wait some someone to jump up and tell me why this should not be done!

 

ChrisH

 

P.S. Tubal Cains Hardening and Heat treatment is on my “to buy” list! 

Edited By ChrisH on 01/02/2011 10:45:38

[Keith LongParticipant @keithlong89920]

Hi Chris

For the steadies virtually anything will do for the material – if you were desperate double the thickness of plywood would probably work fine as well.

In the article Harold states in the small “background” box the he used standard “mild steel” sections. I think there is a danger in subsequently quoting material spec numbers that it starts to look far more important and precise than it really is. Aluminium would be quite ok for the bodies of both rests if you happened to have a suitable chuck or came across some at the right price.

In many cases the designs that we see published were originally made from whatever was at hand in the junk box, scrap pile or whatever.

If material specs. really matter for the part being then hopefully the person designing /making it have enough knowledge of what they are doing to realise it and specify accordingly – and preferably state why so subsequent builders know the reasons for the spec.

Keith

[Peter G. ShawParticipant @peterg-shaw75338]

FWIW, Mr. Hall wrote an almost exact equivalent of the current issue’s article in MEW5. Or should it be the other way round? Ne’er mind eh!

 

Anyway, the original used imperial and aluminium.

 

Not that I’ve anything against HH – I think he does some good stuff, but…..

 

Regards,

 

Peter G. Shaw

[mgjParticipant @mgj]

Chris – 220M07 is leaded sulphur bearing low carbon mild containg about .1% carbon. 230M07 doesn’t have the lead, and so doesn’t finish to that lovely high shine with the rainbow patterns – quite so easily.

 

070M20 is IIRC either EN3A or B, which is slightly tougher .2ish % carbon mild steel, so its not as nice to work with.

 

I’m sure the man is right, but it seems a little pedantic to select one over the other on a base for a steady, when half the rest of the world uses even lower strength cast iron or cast LM4 ali which is as close to monkey metal as you can get! This isn’t exactly taking either a lot of load, or a lot of wear (use washers where appropriate), and if you are really worried, case harden where necessary, but I wouldn’t bother. Given how often one actually has to use a steady, this one will see us both out in its normal unadorned state.

 

Keith is dead right about relative importance.

 

Edited By mgj on 01/02/2011 14:50:11

[Gordon WParticipant @gordonw]

I’ve just made a simple ,and very rough, steady to allow me to face a flange on the end of a 4″ dia tube. Piece of black bar 1″ x 1/2″, bent round a former, bent cold. Welded to bit of 2″ x 1/2″ for a base, with clamp screw hole to take original bolt. Drill and tap M10 in 3 places. Make brass end caps for M10 bolts. For heavier use will weld extra stiffening. This is not brilliant but does the job.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, how about this steady which I cobbled together many moons ago to fit my late fathers RandA lathe. It has at least two different steels, a mallable cast butterfly vavle carcus, and a bit of brass. Apart from the HT socket head screws, (which were just available), I’ve no real idea of what the specs for the different metals are.

 

It works fine, only downside, I have to fit it to the lathe at the same time as the piece that is being steadyed, but hey, there was no cost for the materials, just pretty please to my departmental head at the time.

 

Regards Nick.

Edited By Nicholas Farr on 01/02/2011 18:58:08

[ChrisHParticipant @chrish]

mgj, Keith,

 

My sentiments entirely!

 

Chris

[NilochParticipant @niloch]

Section 23 – Material Specifications – of Harold Hall’s Metalworker’s Data Book (Workshop Practice Series No.42) might be helpful for this thread.

[WALLACEParticipant @wallace]

When I started with this metal bashing lark, I brought a pre-war book on engineering – the type of thing I imagine an apprentice would have spent his first weeks wages on.

 

All good stuff – except for the section on materials where it gives specs for ‘Vickers Staybrght’ or ‘ Cast Elektron’ etc etc.

 

Haven’t a clue what they are in terms of what we can buy today !

 

w.

 

 

[David Clark 13Participant @davidclark13]

Hi There

Staybright is a very cheap version of stainles steel.

Easy to bend and machins ok although a bit sticky.

Not sure if vickers staybright is the same.

regards david

 

[John OlsenParticipant @johnolsen79199]

I am very willing to be corrected on this, but I think Elektron was some sort of light alloy, possibly magnesium based.

 

regards

John

[VersabossParticipant @versaboss]

Right you are, John.

and from GB too… as a few seconds with Google unearthed.

More informations here:

http://findarticles.com/p/articles/mi_m3012/is_1_186/ai_n31061289/

Greetings, Hansrudolf

[WALLACEParticipant @wallace]

Hello David.

 

The book’s at my Dads house – I’ll dig it up next time I visit and find some more obscure materials – it must have been a relief all round when it went to EN numbers !

 

W.

[WALLACEParticipant @wallace]

I’ve found the book – so BS 970:1991may seem over complicated – but at least it is a universal standard – unlike these gems –

 

‘ Cenrard’ , ‘ Nicrosilal, ‘Nimol’, ‘Silal’, ‘Norskallory’, ‘Nomag’, ‘Staybright’, ‘F.G.’, Everdur’, ‘Alloy 218’ and ‘Alpax’.

 

All names long consigned to the swarf bin of of history . . .

 

w

[Author]

Posts