Ss 316 with pig iron

[daniH]

I want make 316 grade steel with pig iron, I know about Oxygen furnaces, 

But I have only a 70 kg induction, blowing oxygen need special equipment, I want know any special fluxes or chemicals that can be used for lowering carbon content and proper mixing of alloyed metals

[Steve Sells]

Wow that is a big order, We are blacksmiths not really metallurgists/chemists here, just getting the chrome into solution will be interesting

[JHCC]

I’m curious why you would want to do this in the first place. Would it not be simpler and more economical to purchase the desired alloy?

[daniH]

It's about opportunities, that's why I want make it, instead of buying it,  

I am assure, most of time, blacksmith have more experience, blowing oxygen in molten iron to release di and mono oxides of carbons are ok, but it needs some special equipment like lance , oxygen supply, high pressure , a built in system, etc.... 

 

[Frosty]

No, oxygen injection is not a blacksmith practice, it's not the 19th century, unless it's the 3rd world we typically buy what we need. 

That doesn't mean many of us don't do impractical things just to see if we can pull it off, smiths tend to be natural tinkerers.

Oxygen lances are off the shelf tools, all you'd need is an oxy source and some serious shielding and PPE. I'd really like to assume you have an idea what is going to happen when you inject pure oxygen into a crucible of molten steel. Spectacularly dangerous to life, limb and property hardly covers it. 

Don't get me wrong, if your set up passed MY safety criteria I'd be right there with you. I already have the aluminized fire suit. 

Frosty The Lucky.

[daniH]

Yes it is, blowing oxygen in molten iron, is not an option, in both ways, availability of apparatus and safety issues, 

Thats why I am looking for chemical compositions for carbon reduction, if possible for someone to share. 

[Frosty]

If decarburizing steel is all, it's easy and in fact a process we have many methods to limit or eliminate from forged products. At high temperature the carbon molecule oxidizes faster and more easily than iron. Make your steel thin and heat it to high orange heat and the air will "remove" the carbon.

I'm sure there are chemical solutions to the "problem" but industry standard is oxygen injection. I can't think of the term at the moment, it's a TBI thing but I'm . . . HAH, my dented memory does it AGAIN! It's the "BOP or Basic Oxygen Process", an improvement of the Bessemer process of injecting air.

The issue with using a chemical oxidizer is residue in the iron you'd have to remove, say H2SO4, sulfuric acid. It will decarburize the iron but then you have to remove the sulfur and hydrogen or deal with hot short hydrogen embrittled iron. And remove the oxygen as well, dissolving steel in acid usually results in iron oxide to deal with.

Dan: Availability of apparatus is actually really common depending on where you live, I can pick up an oxygen lance about 15 minutes from here and I live in a modest size city in Alaska. You can even generate the oxygen if you can't find an oxy tank.

See? Knowing your general location can be an important factor to providing useful answers to your questions. We don't want to know your home address, just the general area. For example if you lived in Dayton Ohio I'd just suggest you call a local welding supply and they could tell you where to buy / rent specialty equipment and or chemicals. If on the other hand you lived in Alakunuk I could pick up what you needed and deliver it to the correct bush, flight service for you. Alakunuk is a village in remote Alaska. Make sense?

Anyway, what you want to do isn't a simple process to start with but it can be made very complex and even more dangerous.

Frosty The Lucky.

 

 

[daniH]

Thanks frosty, you are right that Bop or BOF process are used in large scale furnaces. 

I am from Pakistan, steel production is reduced as govt decide to close all larger steel producing furnaces. So a small scale can be a good option. 

We cast the iron, so we are aware of boiling iron very well and we know how to give respect to have respect for molten metal. 

Acids are way long and expensive option for production. Though its most clean method. 

Electric refined iron production is also an option to get nearly pure iron but it also way lengthy and very controlled system requiring setup. 

""" Oh one more thing"" we use the word "steel" only for low carbon iron, with content less than 1 percent. 

Any iron more than 1 percent in carbon is called iron in general. 

 

In case we add low grade non-magnetic steel scrap and melt it, then we add alloyed metals to make it 316 grade, we still need argon to mix the metals properly as cr has low boiling point and will not mix with iron properly, 

 

In general I want avoid mixing of gasses in molten metals. 

[Frosty]

I wish I could be of more help but you already know more about steel production than I do. I'm a hobbiest blacksmith and a long way from a commercial producer.

Frosty The Lucky.

[daniH]

Thanks frosty, I know here on forum, people are more knowledgeable than me. You also have a good knowledge on steel as your first reply was very accurate. 

I was looking to work directly on ore in blast furnace(old methods are still active here) and reduce iron with hydrogen instead of carbon to directly produce low carbon iron but .....! Hydrogen is another trouble in handling and safety, blast furnace guys thinking that I am making something rare

Knowledge is nothing without proper places to apply! 

Well I will wait for more guys to chime in. 

 

I have very low knowledge in forging, I have seen some guys here making Damascus steel and export it. It's also a nice project and my next task

[Frosty]

I think you should stick around, you and I could get a long well. I'd get to tell stories to a fresh audience and get to learn about your land, a real win win.

When you ask questions online you'll get better answers if you tell folks what you want to do first. I realize it's difficult to talk to folks who speak a different language and translation software is worse. Had you told us you wanted to start from ore lots of people here have more experience than I do and you would've gotten detailed information. 

However melting different alloys together is a very different process, heck many different ones depending on alloys. 

Even now I don't know what you really want to do. Smelting, making iron from ore, or making a new to you alloy by combining different alloys.

Frosty The Lucky.

[daniH]

Thanks a lot, i think I share something very directly , so many can not understand. 

The new green steel technology is to melt the iron ore directly without carbon addition to remove oxygen from ore. (Reduction) 

Ahhh steel , it's a long story to make it, some time to do two anti steps to make it, lets discuss 

Reduction is done with carbon to eat oxygen from iron ore, so iron is reduced from ores , but resultant iron is always pig or cast iron with 4 to 8% carbon. 

Then this iron is melted and oxygen is blown to reduce carbon as carbon Di oxide and carbon mono oxide plus some slag. 

When C is less then again iron is melted and alloyed metals are added. 

 

If it's wrought iron, then wrought iron is melted and carbon is added to get proper carbon content and alloyed metals are added. 

 

Alloyed metals have a different gravity , so they not properly mix in iron, e.g iron is stable and melted at 1300c while cr is volatile at this tamp, so Argon gas is blown to make a proper mix of alloys. 

 

 

Now what I discuss in last massage was, to stop emissions of carbons oxides, we have to controle the system from start, 

Iron extraction from ore, c is added to replace oxygen, and then this carbon become a mother problem for steel, nitrogen/hydrogen also work well to reduce iron , purpose is to replace oxygen with any reducing agent. 

Little hurry, I share what I know. 

Oh and melting alloys, it's not a problem but you need time to change chemistry, only 3 percent copper can be dissolved by iron in one melt. So what about Damascus with copper sheets added. 

Induction is power, electricity is charm ,  

I want produce low carbon iron, so I can make some steel alloys as required. 

In ss 202 to 316, carbon is the actual thing. 

Some people are producing SMS from pig, on small scale, but they not use gases like oxygen to remove carbon, they use some chemicals. I am looking for that combination, 

[Irondragon Forge ClayWorks]

Welcome from the Ozark Mountains.

I for one am interested in this subject. Thank you for the easier to understand explanation regarding alloy's. As a blacksmith, I would love to be able to purchase different grades of wrought iron, but alas there are no plants that I know of manufacturing it in the U.S.

I can't control the wind, all I can do is adjust my sail’s.~ Semper Paratus

 

[daniH]

Thanks iron dragon. 

In US, as I know, green steel is IN now a days. Open pit/ cupola furnaces are nearly closed in US and Europe, 

I can suggest you to electro refine iron with nearly 97+ percent pure iron

It may be required some electro plating setup with some good chemical combinations. 

I can provide it to you but I think it's cost will be extra high for low supply+some extra documentation you will required. 

Any questions you have, you can ask, I will share whatever I know, I am a person who prefer to share things , without hiding things.  

 

[patrick]

Hi DaniH-You've raised an interesting question and I may be able to help a little bit. In the US, stainless grades, especially those that are austenitic, are mostly made starting with scrap stainless steel that has a composition close to that desired in the final product. Because the starting material is already loaded with chrome and nickel, special techniques are used to remove what little carbon is in the melt charge. It will be MUCH less that what is in your pig iron. The methods used are either Argon Oxygen Decarburization (AOD) or Vacuum Oxygen Decarburization (VOD). Both methods are used because they substantially limit the amount of chrome that is lost to oxidation. If the conventional methods of removing carbon by blowing oxygen into the liquid metal under normal atmospheric conditions are used, a great deal of chromium is lost and that is very expensive.

If you are starting with conventional pig iron you will not have much chromium in it, but it will be high in carbon. You could used an oxygen blow to get rid of the carbon, but getting the chromium into that melt gets to be a challenge. Adding pure chromium to liquid pure iron is pretty hard because the melting temp of the chromium is a good bit higher than the iron. In conventional steel making this problem is solved by adding something called ferro chrome to the bath. That is a very high chromium, iron carbon alloy. For steels other than the austenitic stainless grades, this method works well because the carbon in the ferro chrome is not so high as to cause a problem. Lots of steel has carbon over 0.10%, in fact quite a bit more. But to successfully make austenitic stainless (316L) you have to get the carbon down below 0.08%. It is getting that low carbon without loosing a substantial portion of the chromium that is so hard. You can do it, you just loose a lot of chrome and that makes for a very expensive heat of steel. This difficulty in getting rid of carbon is one of the reasons that the martensitic stainless grades, which do have some carbon, were the first to made commercially. It took a bit longer to develop the technology to get rid the carbon. 

In your original question you asked if you could add something to a 70Kg melt to get rid of the carbon without blowing in oxygen. The answer is YES! Historically, mill scale, forge scale or other sources of iron oxide where added to furnaces for the purpose of reducing carbon. This was done as part of the puddling process used to make wrought iron and was also used in the open hearth steel making process, which has some similarities to the puddling process. this will not help you get the chromium and nickel into the iron, but it will help you get the carbon out. Here in the west we no longer add mill scale to the pig iron as part of steel making because so much of our steel is make by remelting scrap via electric arc melting. In that process it is more cost effective and faster to just blow oxygen into the liquid steel, but for your situation this may be a workable solution to your carbon issue. Good luck.