How do I recognize hot rolled steel?

Gallery, Projects and General > How do I??

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PekkaNF:
Thank you for description of the mill scale. I have seen it, just haven't recognized it. I think that now I know what kind of texture and corner I'm looking for.

I found a piece of "rail" very nice machined steel that is well aged and machined all over. It is pretty damn hard and nothing less than carbide cuts it. Pitty. it would be very close to right size. only to cut length and mill 10 mm out from top (L=300m) before cutting dovetails, grove and holes in it.

I would use cast iron if I could source right size piece anytime soon without paying premium. I'll see one local scrap yard today and see what they have.

My biggest consern is that is cast iron and HRS sufficiently different material to work as a top slide (bearing). Cast iron is one of those few materials that works pretty with itself as a bearing material. But I have no experience as cast iro - HRS pair.

I'm not planning to try scraping or flaking on this project, therefore sliding surface finishing must me done different manner.

I probably will make a plug/test and a lap before trying the "final cut".

What portions of salt and vinegar is used on traditional scale removal? How long it takes?

Can I use battery acid (sulphuric acid) as "muriatic accid"? I have plenty of citric accid too but access to other strong chemicals here is pretty limited.

Pekka

philf:

--- Quote from: PekkaNF on August 01, 2014, 06:43:54 AM ---
What portions of salt and vinegar is used on traditional scale removal? How long it takes?

Can I use battery acid (sulphuric acid) as "muriatic accid"? I have plenty of citric accid too but access to other strong chemicals here is pretty limited.

--- End quote ---

Pekka,

Muriatic acid is Hydrochloric Acid which is readily available in the UK as Brick or Masonry Cleaner from hardware and DIY stores. I have used the Brick Cleaner further diluted 2:1. It shifts mill scale in around 15 minutes.

Phil.

12345678910:

--- Quote from: philf on August 01, 2014, 08:08:22 AM ---
--- Quote from: PekkaNF on August 01, 2014, 06:43:54 AM ---
What portions of salt and vinegar is used on traditional scale removal? How long it takes?

Can I use battery acid (sulphuric acid) as "muriatic accid"? I have plenty of citric accid too but access to other strong chemicals here is pretty limited.

--- End quote ---

Pekka,

Muriatic acid is Hydrochloric Acid which is readily available in the UK as Brick or Masonry Cleaner from hardware and DIY stores. I have used the Brick Cleaner further diluted 2:1. It shifts mill scale in around 15 minutes.

Phil.

--- End quote ---

Toilet bowl cleaner is often pure acid too, not those coloured thicker ones, but the cheapest ones.
Read the labels.

vtsteam:
I use diluted muriatic acid for scale, and the sodium carbonate electrolysis method for rust. But I have used white (distilled) vinegar and salt before for scale and it just takes longer -- usually overnight for newly purchased material wth thick scale. I do not dilute the vinegar, and just dump in some salt -- no problem if it doesn't all dissolve, you just have a saturated solution -- but I'm sure less will work fine, too. Not critical proportions, I believe.

Andrew likes citric acid. They all work.

Dilute sulfuric probably does too, but personally I feel more comfortable with dilute hardware store muriatic (hydrochloric) for some reason.

re. muriatic: I pour a little from the masonry cleaner bottle into about ten times as much water. I save the dilute stuff in a wide mouth sealed covered plastic container suitably decorated with skull and crossbones and warnings, and use it over and over again until exhausted. I keep it away from machinery and out of reach in the shop, and I only use it outdoors. It will also strip hot dip galvanizing off in a matter of minutes, if you need clean metal for welding or brazing. Does that quit vigorously.

Pekka, re. your rail material that is hard. I also had a piece of what looked like rail from a junkyard, but it actually turned out to be cast iron -- easily shattered with a sledge hammer, and though I'd intended it for a homemade anvil, I decided it wasn't suitable for that, and have found that it is fine material for melting when doing iron casting (last summer).

So. not all rail is steel, though this stuff might not have been "real" rail.

PekkaNF:
Thank you all for great info.

Tried to hit scrap yard in time....ended there five minutes before closing and they did not want to cut 1m out off 6 m bar of 40*100 HRS. I'll have that on monday.

But I'll entertain myself trying to descale some hot rolled square steel and trying to cut some 60 degree angle to it.

Put about 2 pints of vinegar and 1/2 lbs of salt. Less see.

I think I can recognize mill scale now.

Pekka

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