Talk:Ferrite (iron)

Sentence Structure

In the third paragraph there is a sentence without a verb. The follow on sentence is not clear as to what it is calling beta ferrite.

"Ferrite above the critical temperature A2 (Curie temperature) of 771 °C (1,044 K; 1,420 °F), where it is paramagnetic rather than ferromagnetic. The term is beta ferrite or beta iron (β-Fe)."

I would fix this, but I'm not sure what it is trying to say. Gnuarm (talk) 22:15, 15 March 2017 (UTC)

Hi Gnuarm. This whole article needs work, so I wouldn't trust much of what it says. In specific, ferrite is simply the chemical name for iron, based on the Latin word for the same. Ferrite typically comes in thee different crystalline forms, which are alpha ferrite (or "alpha iron" if you prefer), gamma ferrite, and delta ferrite. Alpha ferrite is a body-centered cubic, which is magnetic (or is attracted to magnets). Gamma ferrite is a face-centered cubic which is non-magnetic. The A² critical temperature is called an arrest, because that is where the change from alpha to gamma occurs. (If heating the iron and measuring its temp, the temp will stop rising at this critical temperature as the crystals change, and will continue to rise only after the change is complete.) When ferrite crosses the A⁴ temperature, the gamma ferrite changes to delta ferrite, and once again becomes magnetic. Beyond delta ferrite is the melting point. Beta ferrite is just an archaic term, which comes from a recent lack of understanding about iron. (Most of what we know today was only discovered between the 1930s and the 1970s, when Bain and his contemporaries were doing their great work, and, unfortunately, many of the myths still remain.)

The process becomes a little more complicated when carbon becomes involved. Pure iron is very rare, and usually only found in laboratories. Most iron contains some amount of carbon. At a carbon level above 0.2%, the iron is termed steel. The A² temperature only exists for pure iron. For steel, it splits into the A¹ and the A³ temps. The former is where a microstructure called pearlite forms upon cooling, while the latter is where gamma-ferrite forms upon heating. Thus, these two temperatures are affected by carbon content. Immediately when gamma ferrite forms, carbon begins mixing with it, forming a solution of iron and carbon called austenite. (Austenite is the name of the solution, not simply another name for gamma ferrite. Austenite doesn't exist in pure iron.) I hope that helps explain. I'll look into fixing this article tomorrow. Zaereth (talk) 02:18, 16 March 2017 (UTC)

Percentage

I am almost certain that the percentages are wrong in the first paragraph. should read 0.3% and not 0.03%

-Peter 80.41.158.216 (talk) 20:21, 1 November 2009 (UTC)

It's correct. I've added a ref to support it. Wizard191 (talk) 01:31, 3 November 2009 (UTC)

Strength

The page says the strength is 280 N/mm^2, but "strength" there should presumably be stiffness (Young's modulus). Fathead99 (talk) 10:41, 1 September 2010 (UTC)

Huh? I don't understand your request. Wizard191 (talk) 13:40, 1 September 2010 (UTC)

Can somebody put this into laymans terms? Or compare it to a standard medium? Because it's quite vague. https://en.wikipedia.org/wiki/Special:Contributions/82.16.95.177 11:16, 17 July 2015

The sentence in question is probably referring to tensile strength rather than yield or shear strength. It's difficult to know without checking my books first, but the number is just about right for tensile. Ferrite has extremely low strength compared to steel. In layman's terms, this means it is very malleable and formable, easily bends, easily tears apart, easily cuts, and does not hold its shape well under a load. Tensile strength, in particular, is how much force is required to pull it apart. (More accurately, it is how far the metal stretches, deforms and gets skinnier at the moment it tears apart.) According to the article, that's around 280 newtons per square millimeter. (N/mm² is somewhat of an archaic unit, as it is usually called megapascals today.) By comparison, pearlite (steel) is more like 600 MPa while martensite is typically higher than 1200 MPa.

Personally, I think this article should be merged with the iron article, because ferrite is simply the chemical name for iron. Zaereth (talk) 18:06, 17 July 2015 (UTC)

Ok, I did a little checking. Strength is a tricky thing talk about, because you really need to define exactly what you mean. These properties relate to fully-ferritic iron in bulk. The tensile strength is between 180 and 250 MPa. The yield strength is 14 to 103 MPa, and it has a Charpy V-notch of 200 joules. In layman's terms, it has very low strength compared to pearliter, but in turn has very high toughness, ductility and compressive strength.

These measurements refer to the properties of individual crystal grains, and is dependent on the orientation of the grain. Tensile strength is between 5000 and 13000 MPa while shear strength is between 3500 and 8000 MPa. This is probably more relevant, because "ferrite" most often refers to individual grains. In layman's terms, individual grains have a lot more strength, as the weak spots exist at the grain boundaries. Hope that helps. Zaereth (talk) 19:58, 17 July 2015 (UTC)

Steel phases

The little box on the top-right of the article lists the many phases of iron and carbon. However, there are only four phases, austenite, cementite, ferrite and graphite. Everything else are simply microstructures of these four phases, such as pearlite, bainite, and martensite.

Also, the phase diagram is incorrect. On the hypoeutectic side it looks fine. The melting point of iron is 1535 degrees C. However, the hypereutecic side should be much steeper. A cast iron with 6.67% carbon will liquify at 1837 degrees C. This makes sense, because both cementite and graphite have higher melting points than iron. It can also be confirmed in the book Practical heat treating, which is available on google books.

I don't know how to properly correct these things. I mainly do text, not formatting code and creating graphics. If somebody can correct these things, it would be appreciated. Zaereth (talk) 02:16, 1 November 2011 (UTC)

You can edit the infobox by clicking the little linked "e" at its bottom. It seems sensible to group, e.g., pearlite separately from pure phases, or at least to move those mixes of phases to the bottom of the phases section. As for the phase diagram, can you find a phase diagram you believe to be correct (e.g., an Amazon in-book link or Google Books)? If it's wrong, someone will change it. —Ben FrantzDale (talk) 11:27, 1 November 2011 (UTC)

I'll see if I can figure it out when I have more time. Personally, I would group the microstructures in their own infobox, separately from the phases. Before Wizard191 left Wikipedia, (sadly), he corrected the phase diagram on the heat treating article. I prefer the one here, though, rather than the international version, because the different phases are labeled in English, so there is not really a need to click on the picture to find out about it. I'm not sure it's really that important, because these types of cast iron seem to have very little practical use, but it would be nice to correct it anyway. Thanks for your advice. Zaereth (talk) 17:01, 1 November 2011 (UTC)

Major change?

I think this article has mixed up alpha-iron and ferrite.

In my opinion this article describes alpha-iron and not ferrite.

Ferrite is defined as "a solid solution where alpha-iron is the solvent, and that is characterized by a body centered cubic crystal structure"

Any thoughts? — Preceding unsigned comment added by Paal.foyn (talk • contribs) 07:20, 26 June 2014 (UTC)

Ferrite is simply another name for iron. Not a solution, but pure iron. This article has many problems, which I have been meaning to address, but simply haven't gotten around to it yet. In specific, the BCC is alpha-ferrite and the FCC is gamma-ferrite, not austenite. Plus there are other allotropes that, when pure, are also ferrite. Austenite is the solution, formed when the carbon in steel mixes with gamma-ferrite. Zaereth (talk) 04:57, 30 June 2014 (UTC)

Removed statement

I took this out, because it read like a textbook" ...Hence the enthalpy of mixing is positive (unfavourable), but the contribution of entropy to the free energy of solution stabilises the structure at low carbon content. 727 °C (1,341 °F) also is the minimum temperature at which iron-carbon austenite (0.8 wt% C) is stable; at this temperature there is a eutectoid reaction between ferrite, austenite and cementite. "--Smokefoot (talk) 19:28, 13 February 2018 (UTC)

Ferrite is a ceramic for most people ...

The article ferrite is about the room-temperature stable allotrope of Fe. News to me, but maybe I am uncalibrated. A check of Greenwood and Earshaw's "Bible of inorganic chemistry": Lots on ferrite(s), the ceramic variety, zero mention of the term being a synonym for Fe. Googling "ferrite" gives links to important ceramics, but one hit to the metal, i.e. our Wikipedia article.

Iron is our most important metal, so we probably want to get this title right. If any other editors have opinions, leave them here. What I am driving at: change the name.--Smokefoot (talk) 21:02, 13 February 2018 (UTC)

Depends on the people. Ferrite is from the Latin word for iron. If you're a geologist, then this refers to minerals based on iron-oxide. To an engineer, it refers to materials based on iron-oxide (such as but not limited to ceramics). To people who are interested in metallurgy or chemistry, then it is just the scientific name for iron (symbol Fe on the periodic table of elements).

I agree, as I mentions above, that 1.) This article needs a major overhaul, and 2.) this entire article should be merged with the iron article, and perhaps Ferrite should simple be a DAB page. Zaereth (talk) 21:19, 13 February 2018 (UTC)

Let's see if anyone else notices or cares. If nothing, then let's merge into iron. --Smokefoot (talk) 18:31, 14 February 2018 (UTC)

Sounds good to me. (It only took me three years to get someone to notice.) I've been meaning to do some work to this article, and possibly merge it myself, but my time is very limited and my Wikipedia efforts sporadic. (With all I have going on I only have about 10 minutes a day to spend on the computer, and nearly all on Wikipedia.) I've never merged an article but will be happy to help. Zaereth (talk) 00:44, 15 February 2018 (UTC)

Well I was bold (or reckless) and move the unique content to allotropes of iron. I was going to put it into iron, but it seems that the allotrope article is more appropriate. If you disagree, then revert the lot. I dont think that very few use the term ferrite for the metal.--Smokefoot (talk) 23:33, 16 February 2018 (UTC)

I guess I was away when this happened, because I didn't notice until now. That works for me, except maybe... One thing that may be problematic is that Ferrite (iron) now links to the article about magnets. This leaves a lot of articles with links that go to the wrong page now, like Alloy, Heat treating, Tempering (metallurgy) or Japanese swordsmithing, because in certain contexts the word has a connotation that helps distinguish between iron chemistry and iron in bulk. (Similar to BFM where there's a need to distinguish between "plane" (aircraft) and "plane" (geometry).) For example, this line from the Mangalloy article, "Other alloying agents may include metals like nickel and chromium; added most often to austenitic steels as an austenite stabilizer; molybdenum and vanadium; used in non-austenitic steels as a ferrite stabilizer; or even non-metallic elements such as silicon." I could easily change "ferrite" to "iron" but it would just sound weird in this context to any metallurgist or chemist. Yet a link should be provided for those who don't know specifically what it means. Zaereth (talk) 19:24, 1 March 2018 (UTC)

Ferrite (iron) now links to the dab page. Currently too many articles are now linked to that dab page ... cleanup needed as too many articles have links to that dab page. Vsmith (talk) 02:58, 2 March 2018 (UTC)

Undiscussed merge?

When was a merge for this ever discussed? Other, and for something which ought to be a Vital Article for metallurgy and engineering, why was it merged? Andy Dingley (talk) 08:52, 6 June 2018 (UTC)

I think that I was behind this rearrangement, and it appears that the merges were not discussed or presented properly by me. The intent of my actions was to get ferrite aligned with the ceramic, which is the principal definition (I thought) while allowing that in some circles ferrite means a particular form of iron metal.--Smokefoot (talk) 11:58, 6 June 2018 (UTC)