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#1 |
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Alloy steel 5160 (a.k.a. AISI 5160) is a high carbon, chromium containing alloy that is often used to make excellent large knives and swords. It's main commercial use has been in the manufacture of leaf suspension springs for automobiles and trucks. In some parts of the world, such as the Philippines, these leaf springs are scavenged from old vehicles and the steel is forged into edged tools and weapons.
I have been trying to determine the history of 5160 steel, when it was first produced, and when it was first used in the leaf springs of vehicles. Have automobile springs always been made from 5160 steel? Searching the web has not yielded much information and I am obviously not looking in the right places. Perhaps someone can point me in the right direction or has a pertinent reference. Why I'm interested in the 5160 story is that the composition of the alloy and its associated properties make it very useful for large knives and swords, and if we know that this alloy has been used in a particular piece we may be able to date it more precisely. The amount of scrap 5160 available may also be a determining factor. For example, in the immediate post-WWII period huge numbers of U.S. vehicles were made redundant and abandoned or destroyed in the Philippines, at which time large amounts of scrap 5160 would have been available relative to pre-WWII. I'm hoping you have some answers. Regards, Ian. |
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#2 |
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Interesting topic!
Not the answers you seek but more of what you were saying. In Nepal the leaf springs are the main source of raw steel material for the Kukris... http://gurkhakukris.com/Content/cms/index.php?id=43 Moreover, as far as I know most modern combat-ready swords (like those made by Hanwei Forge for example) are made of this steel. |
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#3 |
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Wilkinson sword used steel very similar to 1095. Main sword manufacturers thought this was the best steel to use for swords. If modern makers use some other steels they probably use it due to availability or ease of manufacture as they are now made by stock removal, not forged and shaped..
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#4 |
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Will,
I think the main attractions of 5160 are that it is a readily available, durable steel that can be hardened to take a keen edge, and that it is a type of spring steel that can be bent and it will return to its original state (up to a certain limit of course). The small amount of chromium in the alloy seems important in that respect. The edged weapons and tools in many developing countries are still largely forged by locals from materials on hand, which is why scrap leaf springs are sought out. 5160 does not need to be folded or have an inserted edge because it has desired properties of toughness, edge retention, and springiness without being combined with other metals. For this reason, I know from personal experience that scrap springs have been widely used in the Philippines, Mexico, and Thailand. Interesting to learn from marius that Nepalese kukhri are also made from the same material. Ian Last edited by Ian; 1st March 2020 at 04:58 PM. |
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#5 |
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Well Ian... yes and no.
While some smiths may use it for its availability, it definitely does not explain why big, major, modern companies use it. Hanwei for example has easy access to other high alloyed steels. Its exceptional mechanical properties that makes it an almost ideal steel for swords and other bigger blades. From all I know, it has only two minuses: 1. it is rather sensitive to rusting and, 2. it is somehow harder to be worked. |
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#6 |
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Ian,
Interesting subject. Not sure if this addresses your needs, but I found them informative. Try this one."Leaf Springs: Their Characteristics & Methods of Specification, 1912. Free Google Book. https://books.google.com/books?id=6T...spring&f=false Author says that the modulus of elasticity of all steels are virtually the same. Springs made with carbon steel "ride" the same as those of alloy steel of same dimensions. Alloy improved the resistance to repeated deflections. Other alloy additions modified other desirable qualities in manufacturing & use. While not specifically addressed in text 5160's alloy composition enhances other qualities of the carbon steel, not springiness. Steel grade standards developed first for structural steels and then to needs of the train and auto industries for consistency to engineering needs and design qualities. Sword makers in Sudan & elsewhere transitioned from bloomery irons to a good material, i.e. carbon alloy steels from railroads or lorry springs when they became available after c. 1900. I guess it just happened that what steel that made good vehicle springs also made good swords. Regards, Ed |
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#7 |
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Hi Folks,
An overview of 5160:https://www.azom.com/article.aspx?ArticleID=6743 A good article on how to best heat treat 5160: https://knifesteelnerds.com/2019/04/...at-treat-5160/ And where 5160 sits in terms of toughness among forging cutlery steels: https://knifesteelnerds.com/2020/02/...-knife-steels/ Ian: You could ask Larrin at Knife Steel nerds when 5160 came into generall usage: https://knifesteelnerds.com/ Cheers Chris |
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#8 |
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Marius, Ed and Chris.
Thanks for your thoughts and suggestions. Much appreciated. I will report back here if I discover anything useful. Ian. |
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#9 | ||
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Chris,
I sent off an email to Larrin Thomas, as you suggested. What a nice guy! He sent me a prompt reply which is copied below. Quote:
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#10 |
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Very interesting. Thank you!
But actually this steel could have existed much earlier, maybe with small variations, only it was not analysed and documented. It was only with Industrial Revolution that steels have started to be studied systematically. Prior to that it was only empirical study by trial and error. After all, every 16th century rapier blade is a spring... but not even its maker knew its composition. |
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#11 |
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Do you have an EN number for it?
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#12 | |
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This website lists a number of equivalent standards, among which is EN - 60Cr3 http://www.zknives.com/knives/steels...&dlm=AISI&ss=1 Ian: Thank you for publishing Larrin's reply, which is very informative. Cheers Chris |
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#13 | |
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Leaf springs have been made from a variety of steels, not just 5160. Over the years I have seen mentioned 9260, L6 and the higher carbon content 10xx series including 1095. So we must not make the assumption that just because many leaf springs were made from 5160, that all were of the same material. As an aside, making swords and knives from discarded used leaf springs is not a very good idea because these springs develop micro fatigue cracks that are an invitation for later breakage in a sword of knife. As another aside, the village blacksmiths in SE Asia tend to only harden the edges with a shallow edge quench and leave the rest of the blade soft, which mitigates the above risk, though it would not work all that well with thin bladed swords, at least not to our expectations. Cheers Chris |
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#14 | |
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Cheers Chris |
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#15 | |
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Yes, I suppose chance may have led to an earlier use of a similar alloy, but 5160 is not just carbon and chromium added to iron. The detailed composition is given above. It seems unlikely that earlier smiths would have stumbled upon this precise formula, but I suppose anything is possible. There are non-destructive methods that can now test for mineral content, so your idea could be readily tested using old, well-dated pieces. As for carbon steel alone being springy, that is absolutely true. The quality of a blade depends so much on its tempering, and properly quenched carbon steel can certainly exceed the quality of a poorly tempered 5260 blade. The addition of chromium adds durability toughness to the steel, making it less likely to fail under a load. Ian |
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#16 | |||
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#17 | |
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The practice of recycling used leaf springs is not best practice because for starters one does not know the steel's composition and thus the heat treatment cannot be optimized. And then there's the matter of the said fatigue cracks. In summary, it is one of those things that is widely done in the poorer regions of the world with the assumotion that near enough is good enough and things are OK until they are not. This subject has been discussed over and over on blade smith forums and the experts always prefer new steel of a known composition. After all, plain and low alloy carbon steels are quite cheap. Cheers Chris |
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#18 | |
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The matter of toughness is more complicated and I refer you to the excellent articles on Larrin's website. This one is very recent: https://knifesteelnerds.com/2020/02/...-knife-steels/ Cheers Chris |
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#19 | |
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Here are some interesting perspectives and a nice summary of the state of leaf springs in the early 1900s. It is apparent that the materials from which springs were being made was in a transition from plain carbon steel to alloys that had better properties suited to the greater performance demands of automobiles. At the time of publication (1912) the formulation of these new alloys was still being worked out. Although this book does not use the Society of Automobile Engineers' (SAE) terminology, it is clear that the usual steel used for leaf springs had been SAE 10XX stock, whereas some of the newer alloys included, among others, SAE 51XX materials. The advantages of these new alloys is clearly spelled out.
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From Landau D (ed.) Leaf Springs: Their characteristics and method of specification. Sheldon Axle Company: Wilkes-Barre, PA, 1912. Last edited by Ian; 4th March 2020 at 09:12 AM. |
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#20 |
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Hi Ian,
Thanks for sharing that interesting information - All I can say is that we have come some way way from those days..... Cheers Chris |
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