Light mill scale = good quality steel?

[JD1]

I've been working with steel from 2 different vendors. One has tough mill scale that takes work to get off, the other has light mill scale that comes off easily. I've read that impurities come to the surface during production and form the iron oxide mill scale layer.

So I'm wondering...if there's a lot of mill scale, maybe that means more impurities and a lower quality steel? Light mill scale, fewer impurities and better quality steel?

Just curious, not trying to make a big deal out of it.

[Meltedmetal]

I doubt that it is a reliable measure of steel quality. It may have to do with the number of reworks it gets or the atmosphere in the area where it is heated. Lots of people complain about steel made from scrap but if it is done right the more times it gets remelted the purer it can be made.

[Kelvin]

I've been working with steel from 2 different vendors. One has tough mill scale that takes work to get off, the other has light mill scale that comes off easily. I've read that impurities come to the surface during production and form the iron oxide mill scale layer.

So I'm wondering...if there's a lot of mill scale, maybe that means more impurities and a lower quality steel? Light mill scale, fewer impurities and better quality steel?

Just curious, not trying to make a big deal out of it.

Sounds like the 2 vendors might be selling different types of steel -- plain old hot rolled (with the heavier mill scale) and HRPO with less...

Mill scale isn't really "impurities" ... it's just steel that oxidized because it was hot and exposed to oxygen. With HRPO, much of the scale is removed with acid.

[JD1]

I'm not familiar with HRPO steel, I don't remember anyone around here selling it. You ask for mild steel and you get what you get. Maybe that's a special order.

[flushcut]

Does HRPO stand for hot rolled pickled and oiled?

[Kelvin]

Does HRPO stand for hot rolled pickled and oiled?

Yes. When I've gotten it, it seemed like it was "wet" with something (oil? kerosene? condensation?) and it turned your hands black when you handled it.

[albrightree]

What is Hrpo steel?
HRPO steel is hot rolled steel processed with an acid solution – a technique called pickling – to remove contaminants and other unwanted elements such as stains and rust created by exposure to oxygen on the steel's surface. ... Pickling and oiling makes the steel durable, malleable and cleaner to paint.

https://midwestmaterials.com/product...d-oiled-steel/ - near Cleveland OH !

Sometimes I send stainless work out to a Midwestern screen in Canton, or is it Masillon ?

[Welder Dave]

Common SA516-70 boiler plate usually has a lot of mill scale and it's high quality steel. It probably just depends on the steel making process from the supplier how much mill scale is present.

[John T]

but if it is done right .

This is KEY.

[Jack Ryan]

Pickling and oiling makes the steel durable, malleable and cleaner to paint.

Just curious, how does the process of pickling and oiling make the steel more malleable?

Thanks
Jack

[BD1]

As for removal, have you considered a burnishing tool ? I wouldn't use the Metabo one enough to cover the $800.00 price tag, so I bought an Eastwood. It's been great so far and they gave a 3 year warranty now.
I got it on-sale for $179.00 with free shipping.

https://www.eastwood.com/eastwood-contour-sct.html

[BD1]

As for removal, have you considered a burnishing tool ? I wouldn't use the Metabo one enough to cover the $800.00 price tag, so I bought an Eastwood. It's been great so far and they gave a 3 year warranty now.
I got it on-sale for $179.00 with free shipping.

https://www.eastwood.com/eastwood-contour-sct.html

I used it to clean up this rusted sheet for my tool holder. I've used their narrow wheels for my horseshoe art and it works great.

[Lis2323]

As for removal, have you considered a burnishing tool ? I wouldn't use the Metabo one enough to cover the $800.00 price tag, so I bought an Eastwood. It's been great so far and they gave a 3 year warranty now.
I got it on-sale for $179.00 with free shipping.

https://www.eastwood.com/eastwood-contour-sct.html

Also great for cleaning up the tops of welding tables ….




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[BD1]

Also great for cleaning up the tops of welding tables ….




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I just added a few more drums. They had free shipping on orders over $43.00.
Yes $43.00 . No idea how they came up with that number. Normally it's been over $110.00
Go figure. I really love it !!


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[Munkul]

Millscale varies massively, sometimes one side of a plate will have heavier scale than the other.
We got some flat bar in recently that must have had 20 thou of scale on it, it was solid stuff, flap wheels and wire wheels wouldn't touch it! We had to actually grind the stuff off.

If burnishing drums are truly that good on heavy scale I'd buy a burnisher right now... it's a lot of money for something unknown to me though

[flushcut]

Thank you for the replies on the HRPO.

[CAVEMANN]

Yes [SPAM LINK REMOVED]

Hmm, why the need to post 4 links in two of your posts, none related to welding. Are they carrying a viral payload?

[Lis2323]

Millscale varies massively, sometimes one side of a plate will have heavier scale than the other.
We got some flat bar in recently that must have had 20 thou of scale on it, it was solid stuff, flap wheels and wire wheels wouldn't touch it! We had to actually grind the stuff off.

If burnishing drums are truly that good on heavy scale I'd buy a burnisher right now... it's a lot of money for something unknown to me though

I haven't found an abrasive drum for my Walter burnishing tool to remove HEAVY millscale on plate.


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[BD1]

If burnishing drums are truly that good on heavy scale I'd buy a burnisher right now... it's a lot of money for something unknown to me though [/QUOTE]

A lot of money ?? The Eastwood is inexpensive at $229.00 OR whatever it is. And it has a 3 year Warranty .
METABO is the big $$$$ one, around $800.00
This is the aggressive drum I bought. Didn't even have to try it on that plate I posted.
I love it for the money and 3 warranty.
I have METABO grinders, and consider their's but for my use, Eastwood is adequate.

https://www.eastwood.com/eastwood-co...h-40-grit.html


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[BD1]

I haven't found an abrasive drum for my Walter burnishing tool to remove HEAVY millscale on plate.


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That's because of your location.

I don't know if Eastwood would ship to you.

https://www.eastwood.com/eastwood-co...h-40-grit.html


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[Lis2323]

That's because of your location.

I don't know if Eastwood would ship to you.

https://www.eastwood.com/eastwood-co...h-40-grit.html


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I looked into the drum promo you posted a few months back. I had to put it in my shopping cart and enter location before I knew my TRUE price.

They do ship to Canada but it is not cost effective for me. Two taxes are added when they cross the border and there is always that "unknown" factor of brokerage fees. UPS is notorious for that on items coming into CANADA.....SURPRISE!! and not in a good way.


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[albrightree]

Just curious, how does the process of pickling and oiling make the steel more malleable?

Thanks
Jack

I would imagine the hot rolling process is really what makes the steel more malleable, not so much the pickling, and oiling. This is a good read if you are interested.

This link here : https://worthingtonindustries.com/WI...0WATERMARK.pdf

@ JD1 -I think most of the impurities come out in the blast furnace before the pour and initial cast.

[Jack Ryan]

I would imagine the hot rolling process is really what makes the steel more malleable, not so much the pickling, and oiling. This is a good read if you are interested.

This link here : https://worthingtonindustries.com/WI...0WATERMARK.pdf

And to a large extent - the particular alloy involved.

Thanks for the link - it is an interesting read.

Jack

[Munkul]

A lot of money ?? The Eastwood is inexpensive at $229.00 OR whatever it is. And it has a 3 year Warranty .
METABO is the big $$$$ one, around $800.00
This is the aggressive drum I bought. Didn't even have to try it on that plate I posted.
I love it for the money and 3 warranty.
I have METABO grinders, and consider their's but for my use, Eastwood is adequate.

https://www.eastwood.com/eastwood-co...h-40-grit.html


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Over here it's £300 for an Eastwood and ~£350 for a Metabo. You can get no-name chinese ones for £140.

Obviously I'd go for the metabo . My problem is, right now I couldn't justify £350 on a tool that I don't know how much use it would get... although being able to blend stuff would be nice.
I'd also then need to buy at least one 40G, one 80G and one 120G finishing drum, to cover all bases, so that's another easy £100 down.

If I had a paying job that needed welds blended, I wouldn't even hesitate, I'd just order it. But I don't.