Talk:Unified numbering system

S2 steel
Is S2 steel, often used in screwdriver bits and other tool applications, part of this alloy numbering system? It certainly is not a stainless steel - it will rust fairly readily if exposed to moisture.

UNS C95400 (CDA 954) is not equivalent to Ampco 18
Although previous edits reflecting this were made by a corporate account, UNS C95400 is definitely not equivalent to Ampco 18. Compare UNS C95400 data sheet with Ampco 18 data sheet to see the differences. The website of Western States Metals used as reference was wrong and no longer mentions Ampco 18, compare the current version with an archived version or Google cache (as of Oct 16). Therefore, I removed the incorrect sentence from this article. 83.228.186.82 11:15, 16 October 2007 (UTC)
 * A UNS number only identifies a range of chemical compositions, and establishes no requirements for material properties, heat treatment, form, or quality. That is why a UNS, in itself, is not a material specification. The sources you just provided confirm that Ampco 18 is indeed a proprietary material specification for UNS C95400. More importantly, this is explicitly stated by the UNS index jointly published by the SAE and ASTM, which I will soon add as a reference to this article. The identity of Ampco 18 as UNS C95400 is even advertised in old Ampco pamphlets which I still have.--Yannick 23:30, 22 October 2007 (UTC)
 * And actually Ampco 18 isn't even a proper material specification, because it only offers nominal values without tolerances rather than minimum requirements. So a given product could meet the material properties given by Matweb for C95400 and still be called Ampco 18 by an unscrupulous manufacturer.--Yannick 23:40, 22 October 2007 (UTC)


 * It should be made very clear that Ampco 18 does indeed meet or exceed the properties of C95400 (CDA954) but, (as many have found to their cost), C95400 falls far short of the superior properties of Ampco 18. —Preceding unsigned comment added by Bronzeman53 (talk • contribs) 13:29, 29 October 2007 (UTC)
 * Bronzeman53's statement does not make sense. By definition, a UNS number does not establish material properties; for example, tempering can make a very large difference. C95400 defines an alloy, a range of material compositions, which Ampco 18 meets. So Ampco 18 is an example of a C95400 alloy which nominally meets the properties of Ampco 18. (Without guarantees, since Ampco only offers nominal properties.)--Yannick 00:46, 30 October 2007 (UTC)
 * I see a logical flaw in the statement "UNS C95400 is Ampco 18". If Ampco 18 is an example (or "subset") of C95400 alloys, i.e. there are other C95400 alloys that are not Ampco 18, shouldn't the statement be "Ampco 18 is UNS C95400"? Like in "A sparrow is a bird" and not "A bird is a sparrow"? And the same would apply to all other examples in the article. In my opinion, the order should be reversed to avoid this problem. 84.74.225.9 01:18, 31 October 2007 (UTC)

Let's take a less controversial example to examine the point: UNS S17400 and 17-4PH. (Which also goes by the tradename Carpenter Custom 630, by the way.) I don't have the ASTM/SAE index handy tonight, but I'm sure it shows that 17-4PH is a common tradename of UNS S17400. Now compare the following Matweb datasheets: says UNS S17400 has an ultimate tensile strength of 1030 MPa whereas  says 17-4PH has an ultimate tensile strength of 896 MPa. Should we then conclude that UNS S17400 is a subset of 17-4PH because it has higher strength? Absolutely not. If you look further up on each of those datasheets, you will find that they have very similar chemical compositions. Not identical, because the first one does not offer any tolerances on the chemistry and does not describe all the elements, but this doesn't really matter. Metals are made from rocks and necessarily show variations in chemistry. The real difference between these two datasheets has to do with the form and heat treatment: if you study them in detail you will find that both of them say they are both 17-4PH and UNS S17400, but one is sintered and the other is annealed.

Specifications that identify form, heat treatment, minimum material properties, and quality controls are subsets of this alloy, and these subsets can have even greater variation than the example I gave above. For example, when 17-4PH is heat treated to condition H900, it attains a tensile strength of 1365 MPa. But 17-4PH and UNS S17400 are equivalent alloy designations that share those specification subsets and can both attain that strength.

Getting back to Ampco 18, I have confirmed that the ASTM/SAE index lists it as a common tradename of UNS C95400. In what way is Ampco 18 a subset of C95400? The two datasheets provided by 83.228.186.82 were for different forms of the same alloy, (sand cast versus extruded), so of course they had different material properties. That doesn't make one a subset of the other. Ampco 18 and UNS C95400 are the same alloy.--Yannick 01:04, 2 November 2007 (UTC)

Hey guys, I've noticed that this topic seems to becoming a point of contention, and that the page is teetering on the edge of being in an edit war. Perhaps we should all step back a bit and just not include it as an example. Because that's all the list is...a list of examples. Maybe some other examples should be listed instead? Or maybe there's enough examples there for now. There's plenty of more useful things that can be contributed to this stub of an article. For instance, who governs the system, when it was created, why it was created, a more in depth list of one of the series, etc. --Wizard191 (talk) 18:02, 4 March 2008 (UTC)


 * It is a very slow edit war. But I'm pretty sure I'm only arguing against a single person who probably works for Ampco Metals company, and who has no real interest in improving Wikipedia. User:Ampcometal, who initiated this war, tried to scare me off by emailing me a legal threat about this issue in October. I'm not ready to give in to a herd of sockpuppets with a conflict of interest. It's just a bad precedent to give in to a corporate interest just because they're insistent. If Ampco wins, it won't stop there. Carpenter Steel will start complaining that UNS 17400 is not Custom 630, and so on. I wrote a true and relevant statement and attributed it to a reliable published source. That should be enough to justify keeping it.--Yannick (talk) 02:51, 5 March 2008 (UTC)

As someone who has a manufacturing company that derives a great deal of its turnover from supplying parts where the true and very real differences between Ampco 18 and C95400 are an important consideration for engineering based customers, I am happy to declare an interest in this matter. The fact that this would make at least two people who seem to know what they are talking about and disagree with Yannick over this matter will probably be of no interest to such an obvious “pedant”, (sorry for using genuine English, but I do not know of a sad word like “sockpuppet” for such a person – if there is, I am sure I know who will tell me)! Anyway, I think Wizard191 has the most sensible solution, just remove the example completely and then everyone should be happy. —Preceding unsigned comment added by Bronzeman53 (talk • contribs) 11:59, 6 March 2008 (UTC)


 * No personal attacks, please. If you want to win your point, I'm still willing to read your explanation of the differences between UNS C95400 and Ampco 18. But if you don't like to engage in these pedantic discussions, you may want to reconsider whether you want to participate in writing an encyclopedia.--Yannick (talk) 02:13, 7 March 2008 (UTC)


 * I'm removing the example as this seems to be going nowhere. I have my opinions about the matter, but I don't want to feed the fire anymore than it already is. Either way, we can't go on having an edit war. --Wizard191 (talk) 02:39, 7 March 2008 (UTC)


 * I'm content to leave the article alone while we discuss it. I'm still waiting for someone to counter the arguments I made on November 2nd, 2007, above. But if the discussion does not progress, then my statement should be restored simply because it was true, relevant, and attributed to a reliable published source.--Yannick (talk) 18:07, 8 March 2008 (UTC)

For goodness sake…. I am very new to Wikipedia, this is the first time I have ever been involved with it and am certainly not a veteran of edit wars. However, I can see an obvious flaw in its use in that anyone can make whatever statement they want, no matter how inaccurate and providing they have the time, can perpetuate an argument for as long as the wish.

I have openly declared an interest in that I use Ampco 18 in my manufacturing, if not a pedant, why would someone writing a piece on the unified numbering system insist on the example “C95400 is Ampco 18” when there are probably so many other manufacturers trade names they might have chosen. We could be talking about a disgruntled former employee of Ampco or perhaps a competitor of theirs, who knows?

Anyway, in an attempt to put this to bed, once and for all I will briefly explain why I feel the statement “C95400 is Ampco 18”, is wrong.

Firstly a fact that I know from my own manufacturing experience…Ampco 18 is independently assessed and approved for use in food processing and pharmaceutical production applications…C95400 is not. Someone reading Yannick’s statement on the front page, but not this subsequent discussion, might conclude that they could use C95400 in these areas with impunity…they cannot.

Secondly, Ampco 18 achieves its properties without the addition of Ni, which is vital in ensuring machined parts in this alloy slide on steel without damage. C95400 can have up to 1.5% Ni in the alloy, resulting in wear and premature failure of adjacent sliding surfaces.

Thirdly, the Ampco literature that I have makes reference to an “Ampco phase” and how they control the microstructure such that the beta phase does not break-down into the uncontrolled eutectoid, (which causes a brittleness and weakness), and which can be found in commercial grade C95400 material - I will leave it to others to explain such metallurgical niceties in greater detail.

Please, lets just leave the statement “C95400 is Ampco 18” off the article as suggested and hopefully that will be the end of it. —Preceding unsigned comment added by Bronzeman53 (talk • contribs) 15:41, 10 March 2008 (UTC)
 * 1) we think that its not worth arguing about so shutup about it already!!!! —Preceding unsigned comment added by Paul1892 (talk • contribs) 19:30, 10 March 2008 (UTC)

Third opinion
I am responding to a third opinion request which was listed more than one week ago and drew no responses from third opinion volunteers during the past ten days.

Has this dispute been resolved, or not? I'll watchlist this page until the question has been clarified, so please respond here. Thanks. — Athaenara ✉  02:00, 16 March 2008 (UTC)

As no one has responded in the past week, I have removed this page from my watchlist. — Athaenara ✉  08:20, 25 March 2008 (UTC)

Looks like I'm late to the conversation... We first must clarify that the comparison is between the CONTINUOUS CAST version of Ampco 18, and NOT the Ampco 18W (extruded. )It is true that you cannot say that C95400 and Ampco 18 are not equivalent. However, I believe what needs to be clarified is that both named materials possess the same chemical composition, and are made to the same ASTM Specification (ASTM B505). Both materials in question will meet (and exceed) the same minimum mechanical requirements outlined in ASTM B505. However, due to an additional internal manufacturing process, the Ampco 18 should exceed the minimum mechanical requirements further than the C95400. In most applications the C95400 will perform just as well as the Ampco 18. There ARE a handful of applications that you will want to use the Ampco material. Jaycemyth (talk) 16:27, 6 July 2015 (UTC) Jaycemyth 12:26pm, 6 July 2015