‘Zero carbon steel’

[John ReeseParticipant @johnreese12848]

In the manufacture of steel from gray iron carbon has to be burned out of the melt, releasing carbon dioxide. When steel is melted in an electric furnace the carbon electrodes are consumed releasing carbon dioxide. I suspect that "carbon free steel" mis just an advertising gimmick to appease the greens.

[John ReeseParticipant @johnreese12848]

In the manufacture of steel from gray iron carbon has to be burned out of the melt, releasing carbon dioxide. When steel is melted in an electric furnace the carbon electrodes are consumed releasing carbon dioxide. I suspect that "carbon free steel" is just an advertising gimmick to appease the greens.

[duncan webster 1Participant @duncanwebster1]

never mind burning the carbon out of the pig iron, convertng iron ore to iron causes huge CO2 emmisions. Even if all the carbon was used to react with the oxygen in haematite you would release 3/4 ton of CO2 for every ton of iron, and I'll bet in reality it's a lot more than that.

I agree that we should look to repairing things last longer rather than melting them down and making new ones. My last car had done 160,000 miles when it was scrapped, but it had no rust on the shell at all, and the major engine castings could have been remachined to make an as new engine. It was just economically more sensible to me to scrap it and buy a new one (government scrappage scheme)

[vintagengineerParticipant @vintagengineer]

So how do they remove the high levels of chromium, nickel, stainless steel and tool steel from the mix?

There should be none of these in mild steel yet they are found in all black steel

Having forged black mild steel for numerous years, steel from the last ten years is utter rubbish in so much as sometimes batches behave as it should do and other times it comes out of the fire so hard it shatters on impact.This is due to being made from recycled steel.

I would never use any black steel for structural work.

Posted by SillyOldDuffer on 16/04/2017 13:31:51:

Posted by vintagengineer on 16/04/2017 10:38:19:

Recycled steel is total crap. When they scrap cars they go into a giant shredder and all types of steel is mixed together. So you get high carbon steel mixed with mild steel and this gets made into black steel which is only good for non structural work!

Engineering and structural steel beams are always made from new steel. Some modern cars are now made from boron steel!

Ummm, that's not my understanding of modern steel-making at all. Much has changed since 1980. True that a shredded car contains many impurities. False, that no effort is made to remove impurities before they go into the furnace. Also misleading is the idea that steel-making consists of melting down a random mix of scrap and flogging it off as black steel. Actually, the charge contains minerals added specifically to react with unwanted elements. Oxygen is injected into the molten mix, and a series of carefully managed chemical reactions take place, producing steel to a specification. The impurities end up in the slag and exhaust gases, and may be valuable enough for further recovery. No doubt processes go wrong, but not as often as some imagine.

Now that 'steel to a specification' may not be what you wanted or thought you were buying. For example unwanted Boron in Steel seems more to do with tax dodging than faulty production methods. Steel with Boron in it isn't classified as being "Mild Steel", and this enables it to avoid tariffs. Having avoided tax somewhere in the world, it reappears on the market. Like horse-meat in your Lasagne.

Poor quality steel was much more likely in the past. For example, Nitrides are a problem in Mild Steel made by the original Bessemer Process. The Siemens Process avoided that particular problem, but was much more expensive. Producing 'quality steel' was skilled work. These days, most steel is made using much improved technology, heavily automated and efficient.

Where you might get 'random metal', is from the sort of Foundry that makes cast iron street furniture from scrap. That kind of rough work doesn't call for much science.

Dave

[Neil WyattModerator @neilwyatt]

Something most people don't realise is that most mature forests are carbon neutral. Mature rainforest normally has highly mineralised soils that don't lock up much extra carbon. New tree growth pretty much balances loss and rotting of trees.

Young fast-growing trees store carbon.

Of course if you cut them down to allow another crop, the fate of that carbon depends on how the timber is used. made into violins with a 600 year life span or flatpack furniture with a six year lifespan?

That said, cutting down trees, wherever they grow, releases a lot of the stored carbon.

Healthy blanket bogs do better, storing carbon year in year out, building up layers of peat (unless you use it to fire power stations).

The most effective carbon capture is by the oceans, locking it up as carbonates only to be released by volcanic action…

Neil

[Neil WyattModerator @neilwyatt]

Posted by duncan webster on 16/04/2017 19:18:31:

never mind burning the carbon out of the pig iron, convertng iron ore to iron causes huge CO2 emmisions. Even if all the carbon was used to react with the oxygen in haematite you would release 3/4 ton of CO2 for every ton of iron, and I'll bet in reality it's a lot more than that.

I agree that we should look to repairing things last longer rather than melting them down and making new ones. My last car had done 160,000 miles when it was scrapped, but it had no rust on the shell at all, and the major engine castings could have been remachined to make an as new engine. It was just economically more sensible to me to scrap it and buy a new one (government scrappage scheme)

New processes can use hydrogen instead of carbon to reduce the iron ore.

But does this cause hydrogen embrittlement?

Neil

[SillyOldDufferModerator @sillyoldduffer]

Posted by vintagengineer on 16/04/2017 20:15:13:

So how do they remove the high levels of chromium, nickel, stainless steel and tool steel from the mix?

There should be none of these in mild steel yet they are found in all black steel

Having forged black mild steel for numerous years, steel from the last ten years is utter rubbish in so much as sometimes batches behave as it should do and other times it comes out of the fire so hard it shatters on impact.This is due to being made from recycled steel.

…

Bear in mind that Chromium, Nickel, Manganese, Vanadium, and Tungsten are all much more costly than Iron. It pays to recover them.

Chemists are remarkably good at purifying materials. Nasty black gunk goes into an Oil Refinery and out come pure fuels, plastics, solvents and pharmaceuticals etc.

In the case of steel making, Iron has more affinity for oxygen than the alloy elements. The furnace isn't just melting metal, rather it goes through a number of conversion processes designed to meet a specification. This could include oxidizing all the Iron as a first step, removing slag, then reducing the oxide back to pure Iron again.

I think your bad results aren't simply 'due to being made from recycled steel', not least because most steels have always contained recycled metal. I suggest something a bit more subtle is going on, like the Boron alloys being sold as "Mild Steel" example. Presumably you buy a particular specification rather than just ordering "Black Steel". Next time you get a bad batch, why not have it analysed? If it's not to specification then sue whoever conned you. Dirty work at the crossroads is more likely to be the cause than fundamental shortcomings in modern metallurgy.

Dave

Edit: Can't spell. 

Edited By SillyOldDuffer on 16/04/2017 21:28:15

[duncan webster 1Participant @duncanwebster1]

Posted by Neil Wyatt on 16/04/2017 20:44:37:

Posted by duncan webster on 16/04/2017 19:18:31:

never mind burning the carbon out of the pig iron, convertng iron ore to iron causes huge CO2 emmisions. Even if all the carbon was used to react with the oxygen in haematite you would release 3/4 ton of CO2 for every ton of iron, and I'll bet in reality it's a lot more than that.

I agree that we should look to repairing things last longer rather than melting them down and making new ones. My last car had done 160,000 miles when it was scrapped, but it had no rust on the shell at all, and the major engine castings could have been remachined to make an as new engine. It was just economically more sensible to me to scrap it and buy a new one (government scrappage scheme)

New processes can use hydrogen instead of carbon to reduce the iron ore.

But does this cause hydrogen embrittlement?

Neil

so where do they get the hydrogen from? Most hydrogen is made by reacting steam with methane, which of course produces CO2, so you're no better off. Alternatively you can electrolise water, but then you need large quantities of electricity, which will probably come from fossil fuels, and so it goes on. You could of course use a nuclear reactor to generate the electricity, but to go from a simple blast furnace to that doesn't sound all that economical to me, as well as giving the greenies conniptions.

Same argument applies to the 'zero emmissions' hydrogen powered car, or come to that electric car. Until we have an excess of zero emmissions electricity you might as well burn the solid fuel where you want the power/heat, all these modern technologies are doing is moving the polution elsewhere. I'm led to believe that Germany uses excess wind generated electricity in the middle of the night to produce hydrogen which they pump into the gas main. Sounds silly at first, but I think it's quite sensible. Better than paying the windmill men not to produce which is what we do now.

Edited By duncan webster on 16/04/2017 21:42:08

[Neil WyattModerator @neilwyatt]

Posted by duncan webster on 16/04/2017 21:38:16:

Posted by Neil Wyatt on 16/04/2017 20:44:37:

Posted by duncan webster on 16/04/2017 19:18:31:

never mind burning the carbon out of the pig iron, convertng iron ore to iron causes huge CO2 emmisions. Even if all the carbon was used to react with the oxygen in haematite you would release 3/4 ton of CO2 for every ton of iron, and I'll bet in reality it's a lot more than that.

I agree that we should look to repairing things last longer rather than melting them down and making new ones. My last car had done 160,000 miles when it was scrapped, but it had no rust on the shell at all, and the major engine castings could have been remachined to make an as new engine. It was just economically more sensible to me to scrap it and buy a new one (government scrappage scheme)

New processes can use hydrogen instead of carbon to reduce the iron ore.

But does this cause hydrogen embrittlement?

Neil

so where do they get the hydrogen from? Most hydrogen is made by reacting steam with methane, which of course produces CO2, so you're no better off. Alternatively you can electrolise water, but then you need large quantities of electricity, which will probably come from fossil fuels, and so it goes on. You could of course use a nuclear reactor to generate the electricity, but to go from a simple blast furnace to that doesn't sound all that economical to me, as well as giving the greenies conniptions.

The Swedes are using electrolysis, and they have very little reliance on fossil fuels.

Us greenies are generally more relaxed about nuclear power these days – lesser of two evils

Neil

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